diff --git a/.php_cs b/.php_cs
index cdb2e305..01c6a900 100644
--- a/.php_cs
+++ b/.php_cs
@@ -6,7 +6,8 @@ return PhpCsFixer\Config::create()
         'array_syntax' => ['syntax' => 'short'],
         'blank_line_after_opening_tag' => true,
         'single_blank_line_before_namespace' => true,
-        'no_unused_imports' => true
+        'no_unused_imports' => true,
+        'single_quote' => true
     ])
     ->setFinder(
         PhpCsFixer\Finder::create()
diff --git a/README.md b/README.md
index eb4a891c..7fd4b5b4 100644
--- a/README.md
+++ b/README.md
@@ -4,12 +4,14 @@
 
 [![Scrutinizer Code Quality](https://scrutinizer-ci.com/g/coduo/php-matcher/badges/quality-score.png?b=master)](https://scrutinizer-ci.com/g/coduo/php-matcher/?branch=master)
 
-* [![Build Status](https://travis-ci.org/coduo/php-matcher.svg)](https://travis-ci.org/coduo/php-matcher) - master (3.0.*)
+* [![Build Status](https://travis-ci.org/coduo/php-matcher.svg)](https://travis-ci.org/coduo/php-matcher) - master (3.1.*)
+* [![Build Status](https://travis-ci.org/coduo/php-matcher.svg?branch=3.0)](https://travis-ci.org/coduo/php-matcher) - 3.0.*
 * [![Build Status](https://travis-ci.org/coduo/php-matcher.svg?branch=2.2)](https://travis-ci.org/coduo/php-matcher) - 2.2.*
 * [![Build Status](https://travis-ci.org/coduo/php-matcher.svg?branch=2.1)](https://travis-ci.org/coduo/php-matcher) - 2.1.*
 * [![Build Status](https://travis-ci.org/coduo/php-matcher.svg?branch=2.0)](https://travis-ci.org/coduo/php-matcher) - 2.0.*
 
-[Readme for master (3.0) version](https://github.com/coduo/php-matcher/tree/master/README.md)  
+[Readme for master (3.1) version](https://github.com/coduo/php-matcher/tree/master/README.md)
+[Readme for 3.0 version](https://github.com/coduo/php-matcher/tree/3.0/README.md)  
 [Readme for 2.2 version](https://github.com/coduo/php-matcher/tree/2.2/README.md) 
 [Readme for 2.1 version](https://github.com/coduo/php-matcher/tree/2.1/README.md) 
 [Readme for 2.0 version](https://github.com/coduo/php-matcher/tree/2.0/README.md)  
@@ -100,7 +102,7 @@ $factory = new SimpleFactory();
 $matcher = $factory->createMatcher();
 
 $matcher->match(1, 1);
-$matcher->match('string', 'string')
+$matcher->match('string', 'string');
 ```
 
 ### String matching
@@ -114,7 +116,7 @@ $factory = new SimpleFactory();
 $matcher = $factory->createMatcher();
 
 $matcher->match('Norbert', '@string@');
-$matcher->match("lorem ipsum dolor", "@string@.startsWith('lorem').contains('ipsum').endsWith('dolor')")
+$matcher->match("lorem ipsum dolor", "@string@.startsWith('lorem').contains('ipsum').endsWith('dolor')");
 
 ```
 
@@ -188,12 +190,12 @@ use Coduo\PHPMatcher\Factory\SimpleFactory;
 $factory = new SimpleFactory();
 $matcher = $factory->createMatcher();
 
-$matcher->match("@integer@", "@*@"),
-$matcher->match("foobar", "@*@"),
-$matcher->match(true, "@*@"),
-$matcher->match(6.66, "@*@"),
-$matcher->match(array("bar"), "@wildcard@"),
-$matcher->match(new \stdClass, "@wildcard@"),
+$matcher->match("@integer@", "@*@");
+$matcher->match("foobar", "@*@");
+$matcher->match(true, "@*@");
+$matcher->match(6.66, "@*@");
+$matcher->match(array("bar"), "@wildcard@");
+$matcher->match(new \stdClass, "@wildcard@");
 ```
 
 ### Expression matching 
@@ -279,7 +281,7 @@ $matcher->match(
       '@boolean@',
       '@double@'
   )  
-)
+);
 ```
 
 ### Json matching 
@@ -313,8 +315,7 @@ $matcher->match(
       }
     ]
   }'
-)
-
+);
 ```
 
 ### Xml matching
diff --git a/src/Exception/UnknownTypeException.php b/src/Exception/UnknownTypeException.php
index bed58117..619fcab3 100644
--- a/src/Exception/UnknownTypeException.php
+++ b/src/Exception/UnknownTypeException.php
@@ -10,8 +10,8 @@ class UnknownTypeException extends Exception
 
     public function __construct(string $type)
     {
-        $this->type = "@" . $type . "@";
-        parent::__construct(sprintf("Type pattern \"%s\" is not supported.", $this->type), 0, null);
+        $this->type = '@' . $type . '@';
+        parent::__construct(sprintf('Type pattern "%s" is not supported.', $this->type), 0, null);
     }
 
     public function getType() : string
diff --git a/src/Lexer.php b/src/Lexer.php
index b4a299dc..c2d70631 100644
--- a/src/Lexer.php
+++ b/src/Lexer.php
@@ -27,12 +27,12 @@ final class Lexer extends AbstractLexer
     protected function getCatchablePatterns() : array
     {
         return [
-            "\\.?[a-zA-Z0-9_]+\\(", // expander name
-            "[a-zA-Z0-9.]*", // words
-            "\\-?[0-9]*\\.?[0-9]*", // numbers
+            '\\.?[a-zA-Z0-9_]+\\(', // expander name
+            '[a-zA-Z0-9.]*', // words
+            '\\-?[0-9]*\\.?[0-9]*', // numbers
             "'(?:[^']|'')*'", // string between ' character
-            "\"(?:[^\"]|\"\")*\"", // string between " character,
-            "@[a-zA-Z0-9\\*]+@", // type pattern
+            '"(?:[^"]|"")*"', // string between " character,
+            '@[a-zA-Z0-9\\*]+@', // type pattern
         ];
     }
 
@@ -42,7 +42,7 @@ protected function getCatchablePatterns() : array
     protected function getNonCatchablePatterns() : array
     {
         return [
-            "\\s+",
+            '\\s+',
         ];
     }
 
@@ -107,7 +107,7 @@ protected function getType(&$value) : int
 
     protected function isStringToken(string $value) : bool
     {
-        return in_array(substr($value, 0, 1), ["\"", "'"]);
+        return in_array(substr($value, 0, 1), ['"', "'"]);
     }
 
     protected function isBooleanToken(string $value) : bool
diff --git a/src/Matcher/ArrayMatcher.php b/src/Matcher/ArrayMatcher.php
index 5bbbee75..63d25596 100644
--- a/src/Matcher/ArrayMatcher.php
+++ b/src/Matcher/ArrayMatcher.php
@@ -35,7 +35,7 @@ public function match($value, $pattern) : bool
         }
 
         if (!is_array($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid array.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid array.', gettype($value), new StringConverter($value));
             return false;
         }
 
@@ -64,7 +64,7 @@ private function isArrayPattern($pattern) : bool
         return $this->parser->hasValidSyntax($pattern) && $this->parser->parse($pattern)->is(self::PATTERN);
     }
 
-    private function iterateMatch(array $values, array $patterns, string $parentPath = "") : bool
+    private function iterateMatch(array $values, array $patterns, string $parentPath = '') : bool
     {
         $pattern = null;
         foreach ($values as $key => $value) {
@@ -222,12 +222,12 @@ private function setMissingElementInError(string $place, string $path)
 
     private function formatAccessPath($key) : string
     {
-        return sprintf("[%s]", $key);
+        return sprintf('[%s]', $key);
     }
 
     private function formatFullPath(string $parentPath, string $path) : string
     {
-        return sprintf("%s%s", $parentPath, $path);
+        return sprintf('%s%s', $parentPath, $path);
     }
 
     private function shouldSkippValueMatchingFor($lastPattern) : bool
diff --git a/src/Matcher/BooleanMatcher.php b/src/Matcher/BooleanMatcher.php
index 3231f6d2..3d9f5065 100644
--- a/src/Matcher/BooleanMatcher.php
+++ b/src/Matcher/BooleanMatcher.php
@@ -21,7 +21,7 @@ public function __construct(Parser $parser)
     public function match($value, $pattern) : bool
     {
         if (!is_bool($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid boolean.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid boolean.', gettype($value), new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/DoubleMatcher.php b/src/Matcher/DoubleMatcher.php
index 8ae5765d..6d639e02 100644
--- a/src/Matcher/DoubleMatcher.php
+++ b/src/Matcher/DoubleMatcher.php
@@ -21,7 +21,7 @@ public function __construct(Parser $parser)
     public function match($value, $pattern) : bool
     {
         if (!is_double($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid double.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid double.', gettype($value), new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/ExpressionMatcher.php b/src/Matcher/ExpressionMatcher.php
index ef99b164..3b6c99f7 100644
--- a/src/Matcher/ExpressionMatcher.php
+++ b/src/Matcher/ExpressionMatcher.php
@@ -18,7 +18,7 @@ public function match($value, $pattern) : bool
         $expressionResult = $language->evaluate($matches[1], ['value' => $value]);
 
         if (!$expressionResult) {
-            $this->error = sprintf("\"%s\" expression fails for value \"%s\".", $pattern, new StringConverter($value));
+            $this->error = sprintf('"%s" expression fails for value "%s".', $pattern, new StringConverter($value));
         }
 
         return (bool) $expressionResult;
diff --git a/src/Matcher/IntegerMatcher.php b/src/Matcher/IntegerMatcher.php
index 1c669e6d..14656920 100644
--- a/src/Matcher/IntegerMatcher.php
+++ b/src/Matcher/IntegerMatcher.php
@@ -21,7 +21,7 @@ public function __construct(Parser $parser)
     public function match($value, $pattern) : bool
     {
         if (!is_integer($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid integer.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid integer.', gettype($value), new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/JsonMatcher.php b/src/Matcher/JsonMatcher.php
index d457b6dd..f208b297 100644
--- a/src/Matcher/JsonMatcher.php
+++ b/src/Matcher/JsonMatcher.php
@@ -22,12 +22,12 @@ public function match($value, $pattern) : bool
         }
 
         if (!Json::isValid($value)) {
-            $this->error = sprintf("Invalid given JSON of value. %s", $this->getErrorMessage());
+            $this->error = sprintf('Invalid given JSON of value. %s', $this->getErrorMessage());
             return false;
         }
 
         if (!Json::isValidPattern($pattern)) {
-            $this->error = sprintf("Invalid given JSON of pattern. %s", $this->getErrorMessage());
+            $this->error = sprintf('Invalid given JSON of pattern. %s', $this->getErrorMessage());
             return false;
         }
 
diff --git a/src/Matcher/NullMatcher.php b/src/Matcher/NullMatcher.php
index 68e388b0..381f8f81 100644
--- a/src/Matcher/NullMatcher.php
+++ b/src/Matcher/NullMatcher.php
@@ -8,7 +8,7 @@
 
 final class NullMatcher extends Matcher
 {
-    const MATCH_PATTERN = "/^@null@$/";
+    const MATCH_PATTERN = '/^@null@$/';
 
     /**
      * {@inheritDoc}
@@ -16,7 +16,7 @@ final class NullMatcher extends Matcher
     public function match($value, $pattern) : bool
     {
         if (null !== $value) {
-            $this->error = sprintf("%s \"%s\" does not match null.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" does not match null.', gettype($value), new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/NumberMatcher.php b/src/Matcher/NumberMatcher.php
index 69bcfe45..b1d8ee2f 100644
--- a/src/Matcher/NumberMatcher.php
+++ b/src/Matcher/NumberMatcher.php
@@ -21,7 +21,7 @@ public function __construct(Parser $parser)
     public function match($value, $pattern) : bool
     {
         if (!is_numeric($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid number.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid number.', gettype($value), new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/Contains.php b/src/Matcher/Pattern/Expander/Contains.php
index d941fce4..4bad1d78 100644
--- a/src/Matcher/Pattern/Expander/Contains.php
+++ b/src/Matcher/Pattern/Expander/Contains.php
@@ -43,7 +43,7 @@ public function __construct(string $string, $ignoreCase = false)
     public function match($value) : bool
     {
         if (!is_string($value)) {
-            $this->error = sprintf("Contains expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('Contains expander require "string", got "%s".', new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/Count.php b/src/Matcher/Pattern/Expander/Count.php
index 681d0e43..3f3b9f48 100644
--- a/src/Matcher/Pattern/Expander/Count.php
+++ b/src/Matcher/Pattern/Expander/Count.php
@@ -28,12 +28,12 @@ public function __construct(int $value)
     public function match($value) :bool
     {
         if (!is_array($value)) {
-            $this->error = sprintf("Count expander require \"array\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('Count expander require "array", got "%s".', new StringConverter($value));
             return false;
         }
 
         if (count($value) !== $this->value) {
-            $this->error = sprintf("Expected count of %s is %s.", new StringConverter($value), new StringConverter($this->value));
+            $this->error = sprintf('Expected count of %s is %s.', new StringConverter($value), new StringConverter($this->value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/EndsWith.php b/src/Matcher/Pattern/Expander/EndsWith.php
index d192e50f..6b28866c 100644
--- a/src/Matcher/Pattern/Expander/EndsWith.php
+++ b/src/Matcher/Pattern/Expander/EndsWith.php
@@ -20,7 +20,7 @@ final class EndsWith implements PatternExpander
     public function __construct(string $stringEnding, bool $ignoreCase = false)
     {
         if (!is_string($stringEnding)) {
-            throw new \InvalidArgumentException("String ending must be a valid string.");
+            throw new \InvalidArgumentException('String ending must be a valid string.');
         }
 
         $this->stringEnding = $stringEnding;
@@ -35,7 +35,7 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (!is_string($value)) {
-            $this->error = sprintf("EndsWith expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('EndsWith expander require "string", got "%s".', new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/GreaterThan.php b/src/Matcher/Pattern/Expander/GreaterThan.php
index a52453e7..5bd3fe2c 100644
--- a/src/Matcher/Pattern/Expander/GreaterThan.php
+++ b/src/Matcher/Pattern/Expander/GreaterThan.php
@@ -18,7 +18,7 @@ final class GreaterThan implements PatternExpander
     public function __construct($boundary)
     {
         if (!is_float($boundary) && !is_int($boundary)) {
-            throw new \InvalidArgumentException(sprintf("Boundary value \"%s\" is not a valid number.", new StringConverter($boundary)));
+            throw new \InvalidArgumentException(sprintf('Boundary value "%s" is not a valid number.', new StringConverter($boundary)));
         }
 
         $this->boundary = $boundary;
@@ -32,12 +32,12 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (!is_float($value) && !is_int($value) && !is_numeric($value)) {
-            $this->error = sprintf("Value \"%s\" is not a valid number.", new StringConverter($value));
+            $this->error = sprintf('Value "%s" is not a valid number.', new StringConverter($value));
             return false;
         }
 
         if ($value <= $this->boundary) {
-            $this->error = sprintf("Value \"%s\" is not greater than \"%s\".", new StringConverter($value), new StringConverter($this->boundary));
+            $this->error = sprintf('Value "%s" is not greater than "%s".', new StringConverter($value), new StringConverter($this->boundary));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/InArray.php b/src/Matcher/Pattern/Expander/InArray.php
index d385cdb4..c226f9a7 100644
--- a/src/Matcher/Pattern/Expander/InArray.php
+++ b/src/Matcher/Pattern/Expander/InArray.php
@@ -28,7 +28,7 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (!is_array($value)) {
-            $this->error = sprintf("InArray expander require \"array\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('InArray expander require "array", got "%s".', new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/IsDateTime.php b/src/Matcher/Pattern/Expander/IsDateTime.php
index 92b2518f..19ae7d29 100644
--- a/src/Matcher/Pattern/Expander/IsDateTime.php
+++ b/src/Matcher/Pattern/Expander/IsDateTime.php
@@ -21,12 +21,12 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (false === is_string($value)) {
-            $this->error = sprintf("IsDateTime expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('IsDateTime expander require "string", got "%s".', new StringConverter($value));
             return false;
         }
 
         if (false === $this->matchValue($value)) {
-            $this->error = sprintf("string \"%s\" is not a valid date.", $value);
+            $this->error = sprintf('string "%s" is not a valid date.', $value);
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/IsEmail.php b/src/Matcher/Pattern/Expander/IsEmail.php
index acde0409..d1de7616 100644
--- a/src/Matcher/Pattern/Expander/IsEmail.php
+++ b/src/Matcher/Pattern/Expander/IsEmail.php
@@ -21,12 +21,12 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (false === is_string($value)) {
-            $this->error = sprintf("IsEmail expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('IsEmail expander require "string", got "%s".', new StringConverter($value));
             return false;
         }
 
         if (false === $this->matchValue($value)) {
-            $this->error = sprintf("string \"%s\" is not a valid e-mail address.", $value);
+            $this->error = sprintf('string "%s" is not a valid e-mail address.', $value);
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/IsEmpty.php b/src/Matcher/Pattern/Expander/IsEmpty.php
index dea00962..41ab5578 100644
--- a/src/Matcher/Pattern/Expander/IsEmpty.php
+++ b/src/Matcher/Pattern/Expander/IsEmpty.php
@@ -21,7 +21,7 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (!empty($value)) {
-            $this->error = sprintf("Value %s is not empty.", new StringConverter($value));
+            $this->error = sprintf('Value %s is not empty.', new StringConverter($value));
 
             return false;
         }
diff --git a/src/Matcher/Pattern/Expander/IsNotEmpty.php b/src/Matcher/Pattern/Expander/IsNotEmpty.php
index 6ea4dd31..69215752 100644
--- a/src/Matcher/Pattern/Expander/IsNotEmpty.php
+++ b/src/Matcher/Pattern/Expander/IsNotEmpty.php
@@ -21,7 +21,7 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (false === $value || (empty($value) && '0' != $value)) {
-            $this->error = sprintf("Value %s is not blank.", new StringConverter($value));
+            $this->error = sprintf('Value %s is not blank.', new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/IsUrl.php b/src/Matcher/Pattern/Expander/IsUrl.php
index 8663f1e5..257aed0b 100644
--- a/src/Matcher/Pattern/Expander/IsUrl.php
+++ b/src/Matcher/Pattern/Expander/IsUrl.php
@@ -21,12 +21,12 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (false === is_string($value)) {
-            $this->error = sprintf("IsUrl expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('IsUrl expander require "string", got "%s".', new StringConverter($value));
             return false;
         }
 
         if (false === $this->matchValue($value)) {
-            $this->error = sprintf("string \"%s\" is not a valid URL.", $value);
+            $this->error = sprintf('string "%s" is not a valid URL.', $value);
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/LowerThan.php b/src/Matcher/Pattern/Expander/LowerThan.php
index 39a744b9..d752e9ea 100644
--- a/src/Matcher/Pattern/Expander/LowerThan.php
+++ b/src/Matcher/Pattern/Expander/LowerThan.php
@@ -19,7 +19,7 @@ final class LowerThan implements PatternExpander
     public function __construct($boundary)
     {
         if (!is_float($boundary) && !is_integer($boundary) && !is_double($boundary)) {
-            throw new \InvalidArgumentException(sprintf("Boundary value \"%s\" is not a valid number.", new StringConverter($boundary)));
+            throw new \InvalidArgumentException(sprintf('Boundary value "%s" is not a valid number.', new StringConverter($boundary)));
         }
 
         $this->boundary = $boundary;
@@ -33,12 +33,12 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (!is_float($value) && !is_integer($value) && !is_double($value)) {
-            $this->error = sprintf("Value \"%s\" is not a valid number.", new StringConverter($value));
+            $this->error = sprintf('Value "%s" is not a valid number.', new StringConverter($value));
             return false;
         }
 
         if ($value >= $this->boundary) {
-            $this->error = sprintf("Value \"%s\" is not lower than \"%s\".", new StringConverter($value), new StringConverter($this->boundary));
+            $this->error = sprintf('Value "%s" is not lower than "%s".', new StringConverter($value), new StringConverter($this->boundary));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/Expander/MatchRegex.php b/src/Matcher/Pattern/Expander/MatchRegex.php
index 6ac87b35..f82e33a2 100644
--- a/src/Matcher/Pattern/Expander/MatchRegex.php
+++ b/src/Matcher/Pattern/Expander/MatchRegex.php
@@ -18,11 +18,11 @@ final class MatchRegex implements PatternExpander
     public function __construct($pattern)
     {
         if (!is_string($pattern)) {
-            throw new \InvalidArgumentException("Regex pattern must be a string.");
+            throw new \InvalidArgumentException('Regex pattern must be a string.');
         }
 
         if (!is_string($pattern) || @preg_match($pattern, '') === false) {
-            throw new \InvalidArgumentException("Regex pattern must be a valid one.");
+            throw new \InvalidArgumentException('Regex pattern must be a valid one.');
         }
 
         $this->pattern = $pattern;
@@ -36,7 +36,7 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (false === is_string($value)) {
-            $this->error = sprintf("Match expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('Match expander require "string", got "%s".', new StringConverter($value));
 
             return false;
         }
diff --git a/src/Matcher/Pattern/Expander/OneOf.php b/src/Matcher/Pattern/Expander/OneOf.php
index 70e668e0..23195328 100644
--- a/src/Matcher/Pattern/Expander/OneOf.php
+++ b/src/Matcher/Pattern/Expander/OneOf.php
@@ -21,11 +21,11 @@ final class OneOf implements PatternExpander
     public function __construct()
     {
         if (func_num_args() < 2) {
-            throw new \InvalidArgumentException("OneOf expander require at least two expanders.");
+            throw new \InvalidArgumentException('OneOf expander require at least two expanders.');
         }
         foreach (func_get_args() as $argument) {
             if (!$argument instanceof PatternExpander) {
-                throw new \InvalidArgumentException("OneOf expander require each argument to be a valid PatternExpander.");
+                throw new \InvalidArgumentException('OneOf expander require each argument to be a valid PatternExpander.');
             }
 
             $this->expanders[] = $argument;
@@ -45,7 +45,7 @@ public function match($value) : bool
             }
         }
 
-        $this->error = sprintf("Any expander available in OneOf expander does not match \"%s\".", new StringConverter($value));
+        $this->error = sprintf('Any expander available in OneOf expander does not match "%s".', new StringConverter($value));
         return false;
     }
 
diff --git a/src/Matcher/Pattern/Expander/Repeat.php b/src/Matcher/Pattern/Expander/Repeat.php
index 852caf7e..dc2b26a7 100644
--- a/src/Matcher/Pattern/Expander/Repeat.php
+++ b/src/Matcher/Pattern/Expander/Repeat.php
@@ -47,7 +47,7 @@ public static function is(string $name) : bool
     public function __construct(string $pattern, bool $isStrict = true)
     {
         if (!is_string($pattern)) {
-            throw new \InvalidArgumentException("Repeat pattern must be a string.");
+            throw new \InvalidArgumentException('Repeat pattern must be a string.');
         }
 
         $this->pattern = $pattern;
@@ -69,7 +69,7 @@ public function __construct(string $pattern, bool $isStrict = true)
     public function match($values) : bool
     {
         if (!is_array($values)) {
-            $this->error = sprintf("Repeat expander require \"array\", got \"%s\".", new StringConverter($values));
+            $this->error = sprintf('Repeat expander require "array", got "%s".', new StringConverter($values));
             return false;
         }
 
@@ -102,7 +102,7 @@ private function matchScalar(array $values, Matcher $matcher) : bool
             $match = $matcher->match($value, $this->pattern);
 
             if (!$match) {
-                $this->error = sprintf("Repeat expander, entry n°%d, find error : %s", $index, $matcher->getError());
+                $this->error = sprintf('Repeat expander, entry n°%d, find error : %s', $index, $matcher->getError());
                 return false;
             }
         }
@@ -125,20 +125,20 @@ private function matchJson(array $values, Matcher $matcher) : bool
             $valueKeysLength = count($valueKeys);
 
             if ($this->isStrict && $patternKeysLength !== $valueKeysLength) {
-                $this->error = sprintf("Repeat expander expect to have %d keys in array but get : %d", $patternKeysLength, $valueKeysLength);
+                $this->error = sprintf('Repeat expander expect to have %d keys in array but get : %d', $patternKeysLength, $valueKeysLength);
                 return false;
             }
 
             foreach ($patternKeys as $key) {
                 if (!array_key_exists($key, $value)) {
-                    $this->error = sprintf("Repeat expander, entry n°%d, require \"array\" to have key \"%s\".", $index, $key);
+                    $this->error = sprintf('Repeat expander, entry n°%d, require "array" to have key "%s".', $index, $key);
                     return false;
                 }
 
                 $match = $matcher->match($value[$key], $this->pattern[$key]);
 
                 if (!$match) {
-                    $this->error = sprintf("Repeat expander, entry n°%d, key \"%s\", find error : %s", $index, $key, $matcher->getError());
+                    $this->error = sprintf('Repeat expander, entry n°%d, key "%s", find error : %s', $index, $key, $matcher->getError());
                     return false;
                 }
             }
diff --git a/src/Matcher/Pattern/Expander/StartsWith.php b/src/Matcher/Pattern/Expander/StartsWith.php
index 347ae23d..8fb95138 100644
--- a/src/Matcher/Pattern/Expander/StartsWith.php
+++ b/src/Matcher/Pattern/Expander/StartsWith.php
@@ -20,7 +20,7 @@ final class StartsWith implements PatternExpander
     public function __construct(string $stringBeginning, bool $ignoreCase = false)
     {
         if (!is_string($stringBeginning)) {
-            throw new \InvalidArgumentException("String beginning must be a valid string.");
+            throw new \InvalidArgumentException('String beginning must be a valid string.');
         }
 
         $this->stringBeginning = $stringBeginning;
@@ -36,7 +36,7 @@ public static function is(string $name) : bool
     public function match($value) : bool
     {
         if (!is_string($value)) {
-            $this->error = sprintf("StartsWith expander require \"string\", got \"%s\".", new StringConverter($value));
+            $this->error = sprintf('StartsWith expander require "string", got "%s".', new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/Pattern/RegexConverter.php b/src/Matcher/Pattern/RegexConverter.php
index d580926d..d405750e 100644
--- a/src/Matcher/Pattern/RegexConverter.php
+++ b/src/Matcher/Pattern/RegexConverter.php
@@ -14,13 +14,13 @@ public function toRegex(TypePattern $typePattern) : string
             case 'string':
             case 'wildcard':
             case '*':
-                return "(.+)";
+                return '(.+)';
             case 'number':
-                return "(\\-?[0-9]*[\\.|\\,]?[0-9]*)";
+                return '(\\-?[0-9]*[\\.|\\,]?[0-9]*)';
             case 'integer':
-                return "(\\-?[0-9]*)";
+                return '(\\-?[0-9]*)';
             case 'double':
-                return "(\\-?[0-9]*[\\.|\\,][0-9]*)";
+                return '(\\-?[0-9]*[\\.|\\,][0-9]*)';
             default:
                 throw new UnknownTypeException($typePattern->getType());
         }
diff --git a/src/Matcher/ScalarMatcher.php b/src/Matcher/ScalarMatcher.php
index 9247aa61..6d28653d 100644
--- a/src/Matcher/ScalarMatcher.php
+++ b/src/Matcher/ScalarMatcher.php
@@ -11,7 +11,7 @@ final class ScalarMatcher extends Matcher
     public function match($value, $pattern) : bool
     {
         if ($value !== $pattern) {
-            $this->error = sprintf("\"%s\" does not match \"%s\".", new StringConverter($value), new StringConverter($pattern));
+            $this->error = sprintf('"%s" does not match "%s".', new StringConverter($value), new StringConverter($pattern));
             return false;
         }
 
diff --git a/src/Matcher/StringMatcher.php b/src/Matcher/StringMatcher.php
index b1f25a73..eb23be0a 100644
--- a/src/Matcher/StringMatcher.php
+++ b/src/Matcher/StringMatcher.php
@@ -21,7 +21,7 @@ public function __construct(Parser $parser)
     public function match($value, $pattern) : bool
     {
         if (!is_string($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid string.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid string.', gettype($value), new StringConverter($value));
             return false;
         }
 
diff --git a/src/Matcher/TextMatcher.php b/src/Matcher/TextMatcher.php
index 74cef7db..93a335d2 100644
--- a/src/Matcher/TextMatcher.php
+++ b/src/Matcher/TextMatcher.php
@@ -16,7 +16,7 @@ final class TextMatcher extends Matcher
 {
     const PATTERN_REGEXP = "/@[a-zA-Z\\.]+@(\\.[a-zA-Z0-9_]+\\([a-zA-Z0-9{},:@\\.\"'\\(\\)]*\\))*/";
 
-    const PATTERN_REGEXP_PLACEHOLDER_TEMPLATE = "__PLACEHOLDER%d__";
+    const PATTERN_REGEXP_PLACEHOLDER_TEMPLATE = '__PLACEHOLDER%d__';
 
     /**
      * @var Parser
@@ -44,7 +44,7 @@ public function __construct(ValueMatcher $matcher, Parser $parser)
     public function match($value, $pattern) : bool
     {
         if (!is_string($value)) {
-            $this->error = sprintf("%s \"%s\" is not a valid string.", gettype($value), new StringConverter($value));
+            $this->error = sprintf('%s "%s" is not a valid string.', gettype($value), new StringConverter($value));
             return false;
         }
 
@@ -54,19 +54,19 @@ public function match($value, $pattern) : bool
         try {
             $patternRegex = $this->replacePlaceholderWithPatternRegexes($patternRegex, $patternsReplacedWithRegex);
         } catch (UnknownTypeException $exception) {
-            $this->error = sprintf(sprintf("Type pattern \"%s\" is not supported by TextMatcher.", $exception->getType()));
+            $this->error = sprintf(sprintf('Type pattern "%s" is not supported by TextMatcher.', $exception->getType()));
             return false;
         }
 
         if (!preg_match($patternRegex, $value, $matchedValues)) {
-            $this->error = sprintf("\"%s\" does not match \"%s\" pattern", $value, $pattern);
+            $this->error = sprintf('"%s" does not match "%s" pattern', $value, $pattern);
             return false;
         }
 
         array_shift($matchedValues); // remove matched string
 
         if (count($patternsReplacedWithRegex) !== count($matchedValues)) {
-            $this->error = "Unexpected TextMatcher error.";
+            $this->error = 'Unexpected TextMatcher error.';
             return false;
         }
 
@@ -160,6 +160,6 @@ private function replacePlaceholderWithPatternRegexes(string $patternRegex, arra
      */
     private function prepareRegex(string $patternRegex) : string
     {
-        return "/^" . preg_quote($patternRegex, '/') . "$/";
+        return '/^' . preg_quote($patternRegex, '/') . '$/';
     }
 }
diff --git a/src/Matcher/UuidMatcher.php b/src/Matcher/UuidMatcher.php
index 251a65cf..1fc2097b 100644
--- a/src/Matcher/UuidMatcher.php
+++ b/src/Matcher/UuidMatcher.php
@@ -23,7 +23,7 @@ public function match($value, $pattern) : bool
     {
         if (!is_string($value)) {
             $this->error = sprintf(
-                "%s \"%s\" is not a valid UUID: not a string.",
+                '%s "%s" is not a valid UUID: not a string.',
                 gettype($value),
                 new StringConverter($value)
             );
@@ -32,7 +32,7 @@ public function match($value, $pattern) : bool
 
         if (1 !== preg_match(self::UUID_FORMAT_PATTERN, $value)) {
             $this->error = sprintf(
-                "%s \"%s\" is not a valid UUID: invalid format.",
+                '%s "%s" is not a valid UUID: invalid format.',
                 gettype($value),
                 $value
             );
diff --git a/src/Parser.php b/src/Parser.php
index c22c6be7..0480c384 100644
--- a/src/Parser.php
+++ b/src/Parser.php
@@ -59,7 +59,7 @@ private function getPattern() : AST\Pattern
                 $pattern = new AST\Pattern(new AST\Type($this->lexer->lookahead['value']));
                 break;
             default:
-                $this->unexpectedSyntaxError($this->lexer->lookahead, "@type@ pattern");
+                $this->unexpectedSyntaxError($this->lexer->lookahead, '@type@ pattern');
                 break;
         }
 
@@ -93,17 +93,17 @@ private function getNextExpanderNode()
         $expander = new AST\Expander($this->getExpanderName());
 
         if ($this->endOfPattern()) {
-            $this->unexpectedEndOfString(")");
+            $this->unexpectedEndOfString(')');
         }
 
         $this->addArgumentValues($expander);
 
         if ($this->endOfPattern()) {
-            $this->unexpectedEndOfString(")");
+            $this->unexpectedEndOfString(')');
         }
 
         if (!$this->isNextCloseParenthesis()) {
-            $this->unexpectedSyntaxError($this->lexer->lookahead, ")");
+            $this->unexpectedSyntaxError($this->lexer->lookahead, ')');
         }
 
         return $expander;
@@ -112,7 +112,7 @@ private function getNextExpanderNode()
     private function getExpanderName()
     {
         if ($this->lexer->lookahead['type'] !== Lexer::T_EXPANDER_NAME) {
-            $this->unexpectedSyntaxError($this->lexer->lookahead, ".expanderName(args) definition");
+            $this->unexpectedSyntaxError($this->lexer->lookahead, '.expanderName(args) definition');
         }
         $expander = $this->lexer->lookahead['value'];
         $this->lexer->moveNext();
@@ -137,7 +137,7 @@ private function addArgumentValues(AST\Expander $expander)
             $this->lexer->moveNext();
 
             if ($this->lexer->isNextToken(Lexer::T_CLOSE_PARENTHESIS)) {
-                $this->unexpectedSyntaxError($this->lexer->lookahead, "string, number, boolean or null argument");
+                $this->unexpectedSyntaxError($this->lexer->lookahead, 'string, number, boolean or null argument');
             }
         }
     }
@@ -169,7 +169,7 @@ private function getNextArgumentValue()
         }
 
         if (!$this->lexer->isNextTokenAny($validArgumentTypes)) {
-            $this->unexpectedSyntaxError($this->lexer->lookahead, "string, number, boolean or null argument");
+            $this->unexpectedSyntaxError($this->lexer->lookahead, 'string, number, boolean or null argument');
         }
 
         $tokenType = $this->lexer->lookahead['type'];
@@ -193,7 +193,7 @@ private function getArrayArgument() : array
         }
 
         if (!$this->lexer->isNextToken(Lexer::T_CLOSE_CURLY_BRACE)) {
-            $this->unexpectedSyntaxError($this->lexer->lookahead, "}");
+            $this->unexpectedSyntaxError($this->lexer->lookahead, '}');
         }
 
         $this->lexer->moveNext();
@@ -209,11 +209,11 @@ private function getNextArrayElement(array &$array)
 
         $key = $this->getNextArgumentValue();
         if ($key === self::NULL_VALUE) {
-            $key = "";
+            $key = '';
         }
 
         if (!$this->lexer->isNextToken(Lexer::T_COLON)) {
-            $this->unexpectedSyntaxError($this->lexer->lookahead, ":");
+            $this->unexpectedSyntaxError($this->lexer->lookahead, ':');
         }
 
         $this->lexer->moveNext();
@@ -248,9 +248,9 @@ private function isNextCloseParenthesis() : bool
     private function unexpectedSyntaxError(array $unexpectedToken, string $expected = null)
     {
         $tokenPos = (isset($unexpectedToken['position'])) ? $unexpectedToken['position'] : '-1';
-        $message  = sprintf("line 0, col %d: Error: ", $tokenPos);
-        $message .= (isset($expected)) ? sprintf("Expected \"%s\", got ", $expected) : "Unexpected";
-        $message .= sprintf("\"%s\"", $unexpectedToken['value']);
+        $message  = sprintf('line 0, col %d: Error: ', $tokenPos);
+        $message .= (isset($expected)) ? sprintf('Expected "%s", got ', $expected) : 'Unexpected';
+        $message .= sprintf('"%s"', $unexpectedToken['value']);
 
         throw PatternException::syntaxError($message);
     }
@@ -262,9 +262,9 @@ private function unexpectedSyntaxError(array $unexpectedToken, string $expected
     private function unexpectedEndOfString(string $expected = null)
     {
         $tokenPos = (isset($this->lexer->token['position'])) ? $this->lexer->token['position'] + strlen((string) $this->lexer->token['value']) : '-1';
-        $message  = sprintf("line 0, col %d: Error: ", $tokenPos);
-        $message .= (isset($expected)) ? sprintf("Expected \"%s\", got end of string.", $expected) : "Unexpected";
-        $message .= "end of string";
+        $message  = sprintf('line 0, col %d: Error: ', $tokenPos);
+        $message .= (isset($expected)) ? sprintf('Expected "%s", got end of string.', $expected) : 'Unexpected';
+        $message .= 'end of string';
 
         throw PatternException::syntaxError($message);
     }
diff --git a/src/Parser/ExpanderInitializer.php b/src/Parser/ExpanderInitializer.php
index 21b712f0..84f49ad0 100644
--- a/src/Parser/ExpanderInitializer.php
+++ b/src/Parser/ExpanderInitializer.php
@@ -36,7 +36,7 @@ final class ExpanderInitializer
     public function setExpanderDefinition(string $expanderName, string $expanderFQCN)
     {
         if (!class_exists($expanderFQCN)) {
-            throw new UnknownExpanderClassException(sprintf("Class \"%s\" does not exists.", $expanderFQCN));
+            throw new UnknownExpanderClassException(sprintf('Class "%s" does not exists.', $expanderFQCN));
         }
 
         $this->expanderDefinitions[$expanderName] = $expanderFQCN;
@@ -50,7 +50,7 @@ public function hasExpanderDefinition(string $expanderName) : bool
     public function getExpanderDefinition(string $expanderName) : string
     {
         if (!$this->hasExpanderDefinition($expanderName)) {
-            throw new InvalidArgumentException(sprintf("Definition for \"%s\" expander does not exists.", $expanderName));
+            throw new InvalidArgumentException(sprintf('Definition for "%s" expander does not exists.', $expanderName));
         }
 
         return $this->expanderDefinitions[$expanderName];
@@ -59,7 +59,7 @@ public function getExpanderDefinition(string $expanderName) : string
     public function initialize(ExpanderNode $expanderNode) : PatternExpander
     {
         if (!array_key_exists($expanderNode->getName(), $this->expanderDefinitions)) {
-            throw new UnknownExpanderException(sprintf("Unknown expander \"%s\"", $expanderNode->getName()));
+            throw new UnknownExpanderException(sprintf('Unknown expander "%s"', $expanderNode->getName()));
         }
 
         $reflection = new \ReflectionClass($this->expanderDefinitions[$expanderNode->getName()]);
diff --git a/tests/LexerTest.php b/tests/LexerTest.php
index c36d5976..17239ae4 100644
--- a/tests/LexerTest.php
+++ b/tests/LexerTest.php
@@ -48,12 +48,12 @@ public static function validNumberValuesProvider()
             [1, 1],
             [1.25, 1.25],
             [0, 0],
-            ["125", 125],
-            ["12.15", 12.15],
+            ['125', 125],
+            ['12.15', 12.15],
             [-10, -10],
             [-1.124, -1.124],
-            ["-10", -10],
-            ["-1.24", -1.24]
+            ['-10', -10],
+            ['-1.24', -1.24]
         ];
     }
 
@@ -72,10 +72,10 @@ public function test_boolean_values($value, $expectedValue)
     public static function validBooleanValuesProvider()
     {
         return [
-            ["true", true],
-            ["false", false],
-            ["TRUE", true],
-            ["fAlSe", false]
+            ['true', true],
+            ['false', false],
+            ['TRUE', true],
+            ['fAlSe', false]
         ];
     }
 
@@ -94,9 +94,9 @@ public function test_null_values($value)
     public static function validNullValuesProvider()
     {
         return [
-            ["null"],
-            ["NULL"],
-            ["NuLl"],
+            ['null'],
+            ['NULL'],
+            ['NuLl'],
         ];
     }
 
@@ -114,10 +114,10 @@ public function test_non_token_values($value)
     public static function validNonTokenValuesProvider()
     {
         return [
-            ["@integer"],
-            ["integer@"],
-            ["test"],
-            ["@"]
+            ['@integer'],
+            ['integer@'],
+            ['test'],
+            ['@']
         ];
     }
 
@@ -170,18 +170,18 @@ public function test_type_pattern($value)
         $lexer->setInput($value);
         $lexer->moveNext();
         $this->assertEquals($lexer->lookahead['type'], Lexer::T_TYPE_PATTERN);
-        $this->assertEquals($lexer->lookahead['value'], trim($value, "@"));
+        $this->assertEquals($lexer->lookahead['value'], trim($value, '@'));
     }
 
     public static function validMatcherTypePatterns()
     {
         return [
-            ["@string@"],
-            ["@boolean@"],
-            ["@integer@"],
-            ["@number@"],
-            ["@*@"],
-            ["@wildcard@"]
+            ['@string@'],
+            ['@boolean@'],
+            ['@integer@'],
+            ['@number@'],
+            ['@*@'],
+            ['@wildcard@']
         ];
     }
 
@@ -200,15 +200,15 @@ public function test_expander_name($value, $expectedTokenValue)
     public static function validExpanderNamesProvider()
     {
         return [
-            ["expanderName(", "expanderName"],
-            ["e(", "e"],
-            [".e(", "e"]
+            ['expanderName(', 'expanderName'],
+            ['e(', 'e'],
+            ['.e(', 'e']
         ];
     }
 
     public function test_ignore_whitespaces_between_parenthesis()
     {
-        $expectedTokens = ["type", "expander", "arg1", ",", 2, ",", "arg3", ",", 4, ")"];
+        $expectedTokens = ['type', 'expander', 'arg1', ',', 2, ',', 'arg3', ',', 4, ')'];
         $lexer = new Lexer();
         $lexer->setInput("@type@.expander( 'arg1',    2    ,'arg3',4)");
 
diff --git a/tests/Matcher/ArrayMatcherTest.php b/tests/Matcher/ArrayMatcherTest.php
index fef8a0f1..2cadbff4 100644
--- a/tests/Matcher/ArrayMatcherTest.php
+++ b/tests/Matcher/ArrayMatcherTest.php
@@ -108,19 +108,19 @@ public function test_error_when_matching_fail()
 
     public function test_error_message_when_matching_non_array_value()
     {
-        $this->assertFalse($this->matcher->match(new \DateTime(), "@array@"));
-        $this->assertEquals($this->matcher->getError(), "object \"\\DateTime\" is not a valid array.");
+        $this->assertFalse($this->matcher->match(new \DateTime(), '@array@'));
+        $this->assertEquals($this->matcher->getError(), 'object "\\DateTime" is not a valid array.');
     }
 
     public function test_matching_array_to_array_pattern()
     {
-        $this->assertTrue($this->matcher->match(["foo", "bar"], "@array@"));
-        $this->assertTrue($this->matcher->match(["foo"], "@array@.inArray(\"foo\")"));
+        $this->assertTrue($this->matcher->match(['foo', 'bar'], '@array@'));
+        $this->assertTrue($this->matcher->match(['foo'], '@array@.inArray("foo")'));
         $this->assertTrue($this->matcher->match(
-            ["foo", ["bar"]],
+            ['foo', ['bar']],
             [
-                "@string@",
-                "@array@.inArray(\"bar\")"
+                '@string@',
+                '@array@.inArray("bar")'
             ]
         ));
     }
@@ -163,7 +163,7 @@ public static function positiveMatchData()
             [$simpleArr, $simpleArrPattern],
             [[], []],
             [['foo' => null], ['foo' => null]],
-            [['foo' => null], ['foo' => "@null@"]],
+            [['foo' => null], ['foo' => '@null@']],
             [['key' => 'val'], ['key' => 'val']],
             [[1], [1]],
             [
@@ -226,7 +226,7 @@ public static function negativeMatchData()
 
         return [
             [$simpleArr, $simpleDiff],
-            [["status" => "ok", "data" => [['foo']]], ["status" => "ok", "data" => []]],
+            [['status' => 'ok', 'data' => [['foo']]], ['status' => 'ok', 'data' => []]],
             [[1], []],
             [['key' => 'val'], ['key' => 'val2']],
             [[1], [2]],
diff --git a/tests/Matcher/BooleanMatcherTest.php b/tests/Matcher/BooleanMatcherTest.php
index 45d497a0..bee2225e 100644
--- a/tests/Matcher/BooleanMatcherTest.php
+++ b/tests/Matcher/BooleanMatcherTest.php
@@ -65,22 +65,22 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@boolean@"]
+            ['@boolean@']
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            [true, "@boolean@"],
+            [true, '@boolean@'],
         ];
     }
 
     public static function negativeCanMatchData()
     {
         return [
-            ["@boolean"],
-            ["boolean"],
+            ['@boolean'],
+            ['boolean'],
             [1]
         ];
     }
@@ -88,18 +88,18 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            ["1", "@boolean@"],
-            [new \DateTime(),  "@boolean@"]
+            ['1', '@boolean@'],
+            [new \DateTime(),  '@boolean@']
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [new \stdClass,  "@boolean@", "object \"\\stdClass\" is not a valid boolean."],
-            [1.1, "@boolean@", "double \"1.1\" is not a valid boolean."],
-            ["true", "@string@", "string \"true\" is not a valid boolean."],
-            [['test'], "@boolean@", "array \"Array(1)\" is not a valid boolean."]
+            [new \stdClass,  '@boolean@', 'object "\\stdClass" is not a valid boolean.'],
+            [1.1, '@boolean@', 'double "1.1" is not a valid boolean.'],
+            ['true', '@string@', 'string "true" is not a valid boolean.'],
+            [['test'], '@boolean@', 'array "Array(1)" is not a valid boolean.']
         ];
     }
 }
diff --git a/tests/Matcher/DoubleMatcherTest.php b/tests/Matcher/DoubleMatcherTest.php
index 6df50c27..e315ec7a 100644
--- a/tests/Matcher/DoubleMatcherTest.php
+++ b/tests/Matcher/DoubleMatcherTest.php
@@ -65,23 +65,23 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@double@"]
+            ['@double@']
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            [10.1, "@double@"],
-            [10.1, "@double@.lowerThan(50.12).greaterThan(10)"],
+            [10.1, '@double@'],
+            [10.1, '@double@.lowerThan(50.12).greaterThan(10)'],
         ];
     }
 
     public static function negativeCanMatchData()
     {
         return [
-            ["@double"],
-            ["double"],
+            ['@double'],
+            ['double'],
             [1],
         ];
     }
@@ -89,21 +89,21 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            ["1", "@double@"],
-            [new \DateTime(),  "@double@"],
-            [10,  "@double@"],
-            [4.9, "@double@.greaterThan(5)"],
-            [4.9, "@double@.lowerThan(20).greaterThan(5)"],
+            ['1', '@double@'],
+            [new \DateTime(),  '@double@'],
+            [10,  '@double@'],
+            [4.9, '@double@.greaterThan(5)'],
+            [4.9, '@double@.lowerThan(20).greaterThan(5)'],
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [new \stdClass,  "@integer@", "object \"\\stdClass\" is not a valid double."],
-            [25, "@integer@", "integer \"25\" is not a valid double."],
-            [false, "@integer@", "boolean \"false\" is not a valid double."],
-            [['test'], "@integer@", "array \"Array(1)\" is not a valid double."]
+            [new \stdClass,  '@integer@', 'object "\\stdClass" is not a valid double.'],
+            [25, '@integer@', 'integer "25" is not a valid double.'],
+            [false, '@integer@', 'boolean "false" is not a valid double.'],
+            [['test'], '@integer@', 'array "Array(1)" is not a valid double.']
         ];
     }
 }
diff --git a/tests/Matcher/ExpressionMatcherTest.php b/tests/Matcher/ExpressionMatcherTest.php
index 9c39dcaf..9a4b10dc 100644
--- a/tests/Matcher/ExpressionMatcherTest.php
+++ b/tests/Matcher/ExpressionMatcherTest.php
@@ -76,7 +76,7 @@ public function test_negative_regex_matches($value, $pattern)
     public static function positiveCanMatchData()
     {
         return [
-            ["expr(1 > 2)"],
+            ['expr(1 > 2)'],
             ["expr(value == 'foo')"],
         ];
     }
@@ -84,19 +84,19 @@ public static function positiveCanMatchData()
     public static function negativeCanMatchData()
     {
         return [
-            ["@integer"],
-            ["expr("],
-            ["@string"],
+            ['@integer'],
+            ['expr('],
+            ['@string'],
             [new \stdClass],
-            [["foobar"]]
+            [['foobar']]
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            [4, "expr(value > 2)"],
-            ["foo", "expr(value == 'foo')"],
+            [4, 'expr(value > 2)'],
+            ['foo', "expr(value == 'foo')"],
             [new \DateTime('2014-04-01'), "expr(value.format('Y-m-d') == '2014-04-01')"]
         ];
     }
@@ -104,15 +104,15 @@ public static function positiveMatchData()
     public static function negativeMatchData()
     {
         return [
-            [4, "expr(value < 2)"],
-            ["foo", "expr(value != 'foo')"],
+            [4, 'expr(value < 2)'],
+            ['foo', "expr(value != 'foo')"],
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [4, "expr(value < 2)", "\"expr(value < 2)\" expression fails for value \"4\"."],
+            [4, 'expr(value < 2)', '"expr(value < 2)" expression fails for value "4".'],
             [
                 new \DateTime('2014-04-01'),
                 "expr(value.format('Y-m-d') == '2014-04-02')",
diff --git a/tests/Matcher/IntegerMatcherTest.php b/tests/Matcher/IntegerMatcherTest.php
index fbaf2bbf..390da7e1 100644
--- a/tests/Matcher/IntegerMatcherTest.php
+++ b/tests/Matcher/IntegerMatcherTest.php
@@ -65,23 +65,23 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@integer@"]
+            ['@integer@']
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            [10, "@integer@"],
-            [10, "@integer@.lowerThan(50).greaterThan(1)"],
+            [10, '@integer@'],
+            [10, '@integer@.lowerThan(50).greaterThan(1)'],
         ];
     }
 
     public static function negativeCanMatchData()
     {
         return [
-            ["@integer"],
-            ["integer"],
+            ['@integer'],
+            ['integer'],
             [1]
         ];
     }
@@ -89,18 +89,18 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            ["1", "@integer@"],
-            [new \DateTime(),  "@integer@"]
+            ['1', '@integer@'],
+            [new \DateTime(),  '@integer@']
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [new \stdClass,  "@integer@", "object \"\\stdClass\" is not a valid integer."],
-            [1.1, "@integer@", "double \"1.1\" is not a valid integer."],
-            [false, "@integer@", "boolean \"false\" is not a valid integer."],
-            [['test'], "@integer@", "array \"Array(1)\" is not a valid integer."]
+            [new \stdClass,  '@integer@', 'object "\\stdClass" is not a valid integer.'],
+            [1.1, '@integer@', 'double "1.1" is not a valid integer.'],
+            [false, '@integer@', 'boolean "false" is not a valid integer.'],
+            [['test'], '@integer@', 'array "Array(1)" is not a valid integer.']
         ];
     }
 }
diff --git a/tests/Matcher/NullMatcherTest.php b/tests/Matcher/NullMatcherTest.php
index 66a2c4cb..b876d1c3 100644
--- a/tests/Matcher/NullMatcherTest.php
+++ b/tests/Matcher/NullMatcherTest.php
@@ -65,7 +65,7 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@null@"],
+            ['@null@'],
             [null]
         ];
     }
@@ -73,7 +73,7 @@ public static function positiveCanMatchData()
     public static function positiveMatchData()
     {
         return [
-            [null, "@null@"],
+            [null, '@null@'],
             [null, null],
         ];
     }
@@ -81,8 +81,8 @@ public static function positiveMatchData()
     public static function negativeCanMatchData()
     {
         return [
-            ["@null"],
-            ["null"],
+            ['@null'],
+            ['null'],
             [0]
         ];
     }
@@ -90,19 +90,19 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            ["null", "@null@"],
-            [0,  "@null@"]
+            ['null', '@null@'],
+            [0,  '@null@']
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            ["test", "@null@", "string \"test\" does not match null."],
-            [new \stdClass,  "@null@", "object \"\\stdClass\" does not match null."],
-            [1.1, "@null@", "double \"1.1\" does not match null."],
-            [false, "@null@", "boolean \"false\" does not match null."],
-            [1, "@null@", "integer \"1\" does not match null."]
+            ['test', '@null@', 'string "test" does not match null.'],
+            [new \stdClass,  '@null@', 'object "\\stdClass" does not match null.'],
+            [1.1, '@null@', 'double "1.1" does not match null.'],
+            [false, '@null@', 'boolean "false" does not match null.'],
+            [1, '@null@', 'integer "1" does not match null.']
         ];
     }
 }
diff --git a/tests/Matcher/NumberMatcherTest.php b/tests/Matcher/NumberMatcherTest.php
index f44d1b02..591d194b 100644
--- a/tests/Matcher/NumberMatcherTest.php
+++ b/tests/Matcher/NumberMatcherTest.php
@@ -65,25 +65,25 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@number@"]
+            ['@number@']
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            [10.1, "@number@"],
-            [10, "@number@"],
-            ["25", "@number@"],
-            [10, "@number@.lowerThan(50).greaterThan(1)"],
+            [10.1, '@number@'],
+            [10, '@number@'],
+            ['25', '@number@'],
+            [10, '@number@.lowerThan(50).greaterThan(1)'],
         ];
     }
 
     public static function negativeCanMatchData()
     {
         return [
-            ["@number"],
-            ["number"],
+            ['@number'],
+            ['number'],
             [1]
         ];
     }
@@ -91,17 +91,17 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            [["test"], "@number@"],
-            [new \DateTime(),  "@number@"],
+            [['test'], '@number@'],
+            [new \DateTime(),  '@number@'],
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [new \stdClass,  "@number@", "object \"\\stdClass\" is not a valid number."],
-            [false, "@number@", "boolean \"false\" is not a valid number."],
-            [['test'], "@number@", "array \"Array(1)\" is not a valid number."]
+            [new \stdClass,  '@number@', 'object "\\stdClass" is not a valid number.'],
+            [false, '@number@', 'boolean "false" is not a valid number.'],
+            [['test'], '@number@', 'array "Array(1)" is not a valid number.']
         ];
     }
 }
diff --git a/tests/Matcher/OrMatcherTest.php b/tests/Matcher/OrMatcherTest.php
index b2a5f7aa..a9098ab3 100644
--- a/tests/Matcher/OrMatcherTest.php
+++ b/tests/Matcher/OrMatcherTest.php
@@ -144,7 +144,7 @@ public static function negativeMatchData()
 
         return [
             [$simpleArr, $simpleDiff],
-            [["status" => "ok", "data" => [['foo']]], ["status" => "ok", "data" => []]],
+            [['status' => 'ok', 'data' => [['foo']]], ['status' => 'ok', 'data' => []]],
             [[1], []],
             [['key' => 'val'], ['key' => 'val2']],
             [[1], [2]],
diff --git a/tests/Matcher/Pattern/Expander/ContainsTest.php b/tests/Matcher/Pattern/Expander/ContainsTest.php
index 3fbc7c5d..f0113751 100644
--- a/tests/Matcher/Pattern/Expander/ContainsTest.php
+++ b/tests/Matcher/Pattern/Expander/ContainsTest.php
@@ -21,10 +21,10 @@ public function test_matching_values_ignore_case($needle, $haystack, $expectedRe
     public static function examplesIgnoreCaseProvider()
     {
         return [
-            ["ipsum", "lorem ipsum", true],
-            ["wor", "this is my hello world string", true],
-            ["lol", "lorem ipsum", false],
-            ["NO", "norbert", false]
+            ['ipsum', 'lorem ipsum', true],
+            ['wor', 'this is my hello world string', true],
+            ['lol', 'lorem ipsum', false],
+            ['NO', 'norbert', false]
         ];
     }
 
@@ -40,10 +40,10 @@ public function test_matching_values($needle, $haystack, $expectedResult)
     public static function examplesProvider()
     {
         return [
-            ["IpSum", "lorem ipsum", true],
-            ["wor", "this is my hello WORLD string", true],
-            ["lol", "LOREM ipsum", false],
-            ["NO", "NORBERT", true]
+            ['IpSum', 'lorem ipsum', true],
+            ['wor', 'this is my hello WORLD string', true],
+            ['lol', 'LOREM ipsum', false],
+            ['NO', 'NORBERT', true]
         ];
     }
 
@@ -60,8 +60,8 @@ public function test_error_when_matching_fail($string, $value, $errorMessage)
     public static function invalidCasesProvider()
     {
         return [
-            ["ipsum", "hello world", "String \"hello world\" doesn't contains \"ipsum\"."],
-            ["lorem", new \DateTime(), "Contains expander require \"string\", got \"\\DateTime\"."],
+            ['ipsum', 'hello world', "String \"hello world\" doesn't contains \"ipsum\"."],
+            ['lorem', new \DateTime(), 'Contains expander require "string", got "\\DateTime".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/CountTest.php b/tests/Matcher/Pattern/Expander/CountTest.php
index f8cd9722..153f25f6 100644
--- a/tests/Matcher/Pattern/Expander/CountTest.php
+++ b/tests/Matcher/Pattern/Expander/CountTest.php
@@ -21,8 +21,8 @@ public function test_matching_values($needle, $haystack, $expectedResult)
     public static function examplesProvider()
     {
         return [
-            [1, ["ipsum"], true],
-            [2, ["foo", 1], true],
+            [1, ['ipsum'], true],
+            [2, ['foo', 1], true],
         ];
     }
 
@@ -39,8 +39,8 @@ public function test_error_when_matching_fail($boundary, $value, $errorMessage)
     public static function invalidCasesProvider()
     {
         return [
-            [2, [1, 2, 3], "Expected count of Array(3) is 2."],
-            [2, new \DateTime(), "Count expander require \"array\", got \"\\DateTime\"."],
+            [2, [1, 2, 3], 'Expected count of Array(3) is 2.'],
+            [2, new \DateTime(), 'Count expander require "array", got "\\DateTime".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/EndsWithTest.php b/tests/Matcher/Pattern/Expander/EndsWithTest.php
index fc04d018..b00043d5 100644
--- a/tests/Matcher/Pattern/Expander/EndsWithTest.php
+++ b/tests/Matcher/Pattern/Expander/EndsWithTest.php
@@ -21,11 +21,11 @@ public function test_examples_not_ignoring_case($stringEnding, $value, $expected
     public static function notIgnoringCaseExamplesProvider()
     {
         return [
-            ["ipsum", "lorem ipsum", true],
-            ["ipsum", "Lorem IPSUM", false],
-            ["", "lorem ipsum", true],
-            ["ipsum", "lorem ipsum", true],
-            ["lorem", "lorem ipsum", false]
+            ['ipsum', 'lorem ipsum', true],
+            ['ipsum', 'Lorem IPSUM', false],
+            ['', 'lorem ipsum', true],
+            ['ipsum', 'lorem ipsum', true],
+            ['lorem', 'lorem ipsum', false]
         ];
     }
 
@@ -41,9 +41,9 @@ public function test_examples_ignoring_case($stringEnding, $value, $expectedResu
     public static function ignoringCaseExamplesProvider()
     {
         return [
-            ["Ipsum", "Lorem ipsum", true],
-            ["iPsUm", "lorem ipsum", true],
-            ["IPSUM", "LoReM ipsum", true],
+            ['Ipsum', 'Lorem ipsum', true],
+            ['iPsUm', 'lorem ipsum', true],
+            ['IPSUM', 'LoReM ipsum', true],
         ];
     }
 
@@ -60,8 +60,8 @@ public function test_error_when_matching_fail($stringBeginning, $value, $errorMe
     public static function invalidCasesProvider()
     {
         return [
-            ["ipsum", "ipsum lorem", "string \"ipsum lorem\" doesn't ends with string \"ipsum\"."],
-            ["lorem", new \DateTime(), "EndsWith expander require \"string\", got \"\\DateTime\"."],
+            ['ipsum', 'ipsum lorem', "string \"ipsum lorem\" doesn't ends with string \"ipsum\"."],
+            ['lorem', new \DateTime(), 'EndsWith expander require "string", got "\\DateTime".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/GreaterThanTest.php b/tests/Matcher/Pattern/Expander/GreaterThanTest.php
index 237b74de..cb8fcd69 100644
--- a/tests/Matcher/Pattern/Expander/GreaterThanTest.php
+++ b/tests/Matcher/Pattern/Expander/GreaterThanTest.php
@@ -25,7 +25,7 @@ public static function examplesProvider()
             [-20, -10.5, true],
             [10, 1, false],
             [1, 1, false],
-            [10, "20", true]
+            [10, '20', true]
         ];
     }
 
@@ -42,9 +42,9 @@ public function test_error_when_matching_fail($boundary, $value, $errorMessage)
     public static function invalidCasesProvider()
     {
         return [
-            [1, "ipsum lorem", "Value \"ipsum lorem\" is not a valid number."],
-            [10, 5, "Value \"5\" is not greater than \"10\"."],
-            [5, 5, "Value \"5\" is not greater than \"5\"."],
+            [1, 'ipsum lorem', 'Value "ipsum lorem" is not a valid number.'],
+            [10, 5, 'Value "5" is not greater than "10".'],
+            [5, 5, 'Value "5" is not greater than "5".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/InArrayTest.php b/tests/Matcher/Pattern/Expander/InArrayTest.php
index 12db3136..ea73fe06 100644
--- a/tests/Matcher/Pattern/Expander/InArrayTest.php
+++ b/tests/Matcher/Pattern/Expander/InArrayTest.php
@@ -21,9 +21,9 @@ public function test_matching_values($needle, $haystack, $expectedResult)
     public static function examplesProvider()
     {
         return [
-            ["ipsum", ["ipsum"], true],
-            [1, ["foo", 1], true],
-            [["foo" => "bar"], [["foo" => "bar"]], true],
+            ['ipsum', ['ipsum'], true],
+            [1, ['foo', 1], true],
+            [['foo' => 'bar'], [['foo' => 'bar']], true],
         ];
     }
 
@@ -40,8 +40,8 @@ public function test_error_when_matching_fail($boundary, $value, $errorMessage)
     public static function invalidCasesProvider()
     {
         return [
-            ["ipsum", ["ipsum lorem"], "Array(1) doesn't have \"ipsum\" element."],
-            ["lorem", new \DateTime(), "InArray expander require \"array\", got \"\\DateTime\"."],
+            ['ipsum', ['ipsum lorem'], "Array(1) doesn't have \"ipsum\" element."],
+            ['lorem', new \DateTime(), 'InArray expander require "array", got "\\DateTime".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/IsDateTimeTest.php b/tests/Matcher/Pattern/Expander/IsDateTimeTest.php
index 10459932..0bf74822 100644
--- a/tests/Matcher/Pattern/Expander/IsDateTimeTest.php
+++ b/tests/Matcher/Pattern/Expander/IsDateTimeTest.php
@@ -21,10 +21,10 @@ public function test_dates($date, $expectedResult)
     public static function examplesDatesProvider()
     {
         return [
-            ["201-20-44", false],
-            ["2012-10-11", true],
-            ["invalid", false],
-            ["Monday, 15-Aug-2005 15:52:01 UTC", true]
+            ['201-20-44', false],
+            ['2012-10-11', true],
+            ['invalid', false],
+            ['Monday, 15-Aug-2005 15:52:01 UTC', true]
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/IsEmailTest.php b/tests/Matcher/Pattern/Expander/IsEmailTest.php
index 3f34e76f..a5a4cdc0 100644
--- a/tests/Matcher/Pattern/Expander/IsEmailTest.php
+++ b/tests/Matcher/Pattern/Expander/IsEmailTest.php
@@ -21,10 +21,10 @@ public function test_emails($email, $expectedResult)
     public static function examplesEmailsProvider()
     {
         return [
-            ["valid@email.com", true],
-            ["valid+12345@email.com", true],
-            ["...@domain.com", false],
-            ["2222----###@domain.co", true]
+            ['valid@email.com', true],
+            ['valid+12345@email.com', true],
+            ['...@domain.com', false],
+            ['2222----###@domain.co', true]
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/IsNotEmptyTest.php b/tests/Matcher/Pattern/Expander/IsNotEmptyTest.php
index 34d40618..d935fcf2 100644
--- a/tests/Matcher/Pattern/Expander/IsNotEmptyTest.php
+++ b/tests/Matcher/Pattern/Expander/IsNotEmptyTest.php
@@ -21,10 +21,10 @@ public function test_examples_not_ignoring_case($value, $expectedResult)
     public static function examplesProvider()
     {
         return [
-            ["lorem", true],
-            ["0", true],
+            ['lorem', true],
+            ['0', true],
             [new \DateTime(), true],
-            ["", false],
+            ['', false],
             [null, false],
             [[], false]
         ];
diff --git a/tests/Matcher/Pattern/Expander/IsUrlTest.php b/tests/Matcher/Pattern/Expander/IsUrlTest.php
index 81588273..90a79906 100644
--- a/tests/Matcher/Pattern/Expander/IsUrlTest.php
+++ b/tests/Matcher/Pattern/Expander/IsUrlTest.php
@@ -21,13 +21,13 @@ public function test_urls($url, $expectedResult)
     public static function examplesUrlsProvider()
     {
         return [
-            ["http://example.com/test.html", true],
-            ["https://example.com/test.html", true],
-            ["https://example.com/user/{id}/", true],
-            ["mailto:email@example.com", true],
-            ["//example.com/test/", false],
-            ["example", false],
-            ["", false]
+            ['http://example.com/test.html', true],
+            ['https://example.com/test.html', true],
+            ['https://example.com/user/{id}/', true],
+            ['mailto:email@example.com', true],
+            ['//example.com/test/', false],
+            ['example', false],
+            ['', false]
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/LowerThanTest.php b/tests/Matcher/Pattern/Expander/LowerThanTest.php
index cd09a967..e72b73b7 100644
--- a/tests/Matcher/Pattern/Expander/LowerThanTest.php
+++ b/tests/Matcher/Pattern/Expander/LowerThanTest.php
@@ -41,9 +41,9 @@ public function test_error_when_matching_fail($boundary, $value, $errorMessage)
     public static function invalidCasesProvider()
     {
         return [
-            [1, "ipsum lorem", "Value \"ipsum lorem\" is not a valid number."],
-            [5, 10, "Value \"10\" is not lower than \"5\"."],
-            [5, 5, "Value \"5\" is not lower than \"5\"."],
+            [1, 'ipsum lorem', 'Value "ipsum lorem" is not a valid number.'],
+            [5, 10, 'Value "10" is not lower than "5".'],
+            [5, 5, 'Value "5" is not lower than "5".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/OneOfTest.php b/tests/Matcher/Pattern/Expander/OneOfTest.php
index 94992222..a433015a 100644
--- a/tests/Matcher/Pattern/Expander/OneOfTest.php
+++ b/tests/Matcher/Pattern/Expander/OneOfTest.php
@@ -25,29 +25,29 @@ public function test_not_enough_arguments()
      */
     public function test_invalid_argument_types()
     {
-        $expander = new OneOf("arg1", ["test"]);
+        $expander = new OneOf('arg1', ['test']);
     }
 
     public function test_positive_match()
     {
         $expander = new OneOf(
-            new Contains("lorem"),
-            new Contains("test")
+            new Contains('lorem'),
+            new Contains('test')
         );
 
-        $this->assertTrue($expander->match("lorem ipsum"));
+        $this->assertTrue($expander->match('lorem ipsum'));
     }
 
     public function test_negative_match()
     {
         $expander = new OneOf(
-            new Contains("lorem"),
-            new Contains("test")
+            new Contains('lorem'),
+            new Contains('test')
         );
 
-        $this->assertFalse($expander->match("this is random stiring"));
+        $this->assertFalse($expander->match('this is random stiring'));
         $this->assertSame(
-            "Any expander available in OneOf expander does not match \"this is random stiring\".",
+            'Any expander available in OneOf expander does not match "this is random stiring".',
             $expander->getError()
         );
     }
diff --git a/tests/Matcher/Pattern/Expander/RepeatTest.php b/tests/Matcher/Pattern/Expander/RepeatTest.php
index 520b17a5..1427120f 100644
--- a/tests/Matcher/Pattern/Expander/RepeatTest.php
+++ b/tests/Matcher/Pattern/Expander/RepeatTest.php
@@ -23,20 +23,20 @@ public static function examplesProvider()
         $jsonPattern = '{"name": "@string@", "activated": "@boolean@"}';
 
         $jsonTest = [
-            ["name" => "toto", "activated" => true],
-            ["name" => "titi", "activated" => false],
-            ["name" => "tate", "activated" => true]
+            ['name' => 'toto', 'activated' => true],
+            ['name' => 'titi', 'activated' => false],
+            ['name' => 'tate', 'activated' => true]
         ];
 
-        $scalarPattern = "@string@";
+        $scalarPattern = '@string@';
         $scalarTest = [
-            "toto",
-            "titi",
-            "tata"
+            'toto',
+            'titi',
+            'tata'
         ];
 
         $strictTest = [
-            ["name" => "toto", "activated" => true, "offset" => "offset"]
+            ['name' => 'toto', 'activated' => true, 'offset' => 'offset']
         ];
 
         return [
@@ -61,22 +61,22 @@ public static function invalidCasesProvider()
         $pattern = '{"name": "@string@", "activated": "@boolean@"}';
 
         $valueTest = [
-            ["name" => 1, "activated" => "yes"]
+            ['name' => 1, 'activated' => 'yes']
         ];
 
         $keyTest = [
-            ["offset" => true, "foe" => "bar"]
+            ['offset' => true, 'foe' => 'bar']
         ];
 
         $strictTest = [
-            ["name" => 1, "activated" => "yes", "offset" => true]
+            ['name' => 1, 'activated' => 'yes', 'offset' => true]
         ];
 
         return [
             [$pattern, $valueTest, 'Repeat expander, entry n°0, key "name", find error : integer "1" is not a valid string.'],
             [$pattern, $keyTest, 'Repeat expander, entry n°0, require "array" to have key "name".'],
             [$pattern, $strictTest, 'Repeat expander expect to have 2 keys in array but get : 3'],
-            [$pattern, "", 'Repeat expander require "array", got "".']
+            [$pattern, '', 'Repeat expander require "array", got "".']
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/Expander/StartsWithTest.php b/tests/Matcher/Pattern/Expander/StartsWithTest.php
index ab711299..3caec5c2 100644
--- a/tests/Matcher/Pattern/Expander/StartsWithTest.php
+++ b/tests/Matcher/Pattern/Expander/StartsWithTest.php
@@ -21,11 +21,11 @@ public function test_examples_not_ignoring_case($stringBeginning, $value, $expec
     public static function notIgnoringCaseExamplesProvider()
     {
         return [
-            ["lorem", "lorem ipsum", true],
-            ["lorem", "Lorem ipsum", false],
-            ["", "lorem ipsum", true],
-            ["lorem", "lorem ipsum", true],
-            ["ipsum", "lorem ipsum", false]
+            ['lorem', 'lorem ipsum', true],
+            ['lorem', 'Lorem ipsum', false],
+            ['', 'lorem ipsum', true],
+            ['lorem', 'lorem ipsum', true],
+            ['ipsum', 'lorem ipsum', false]
         ];
     }
 
@@ -41,9 +41,9 @@ public function test_examples_ignoring_case($stringBeginning, $value, $expectedR
     public static function ignoringCaseExamplesProvider()
     {
         return [
-            ["lorem", "Lorem ipsum", true],
-            ["Lorem", "lorem ipsum", true],
-            ["LOREM", "LoReM ipsum", true],
+            ['lorem', 'Lorem ipsum', true],
+            ['Lorem', 'lorem ipsum', true],
+            ['LOREM', 'LoReM ipsum', true],
         ];
     }
 
@@ -60,8 +60,8 @@ public function test_error_when_matching_fail($stringBeginning, $value, $errorMe
     public static function invalidCasesProvider()
     {
         return [
-            ["lorem", "ipsum lorem", "string \"ipsum lorem\" doesn't starts with string \"lorem\"."],
-            ["lorem", new \DateTime(), "StartsWith expander require \"string\", got \"\\DateTime\"."],
+            ['lorem', 'ipsum lorem', "string \"ipsum lorem\" doesn't starts with string \"lorem\"."],
+            ['lorem', new \DateTime(), 'StartsWith expander require "string", got "\\DateTime".'],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/PatternTest.php b/tests/Matcher/Pattern/PatternTest.php
index 7af471c5..6f502775 100644
--- a/tests/Matcher/Pattern/PatternTest.php
+++ b/tests/Matcher/Pattern/PatternTest.php
@@ -37,11 +37,11 @@ public function test_has_expander($expander, $expectedResult)
     public static function examplesProvider()
     {
         return [
-            ["isEmail", true],
-            ["isEmpty", true],
-            ["optional", true],
-            ["isUrl", false],
-            ["non existing expander", false],
+            ['isEmail', true],
+            ['isEmpty', true],
+            ['optional', true],
+            ['isUrl', false],
+            ['non existing expander', false],
         ];
     }
 }
diff --git a/tests/Matcher/Pattern/RegexConverterTest.php b/tests/Matcher/Pattern/RegexConverterTest.php
index 0f04e885..7d695b10 100644
--- a/tests/Matcher/Pattern/RegexConverterTest.php
+++ b/tests/Matcher/Pattern/RegexConverterTest.php
@@ -25,6 +25,6 @@ public function setUp()
      */
     public function test_convert_unknown_type()
     {
-        $this->converter->toRegex(new TypePattern("not_a_type"));
+        $this->converter->toRegex(new TypePattern('not_a_type'));
     }
 }
diff --git a/tests/Matcher/ScalarMatcherTest.php b/tests/Matcher/ScalarMatcherTest.php
index 952ef483..50587310 100644
--- a/tests/Matcher/ScalarMatcherTest.php
+++ b/tests/Matcher/ScalarMatcherTest.php
@@ -58,10 +58,10 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function negativeMatches()
     {
         return [
-            [false, "false"],
+            [false, 'false'],
             [false, 0],
             [true, 1],
-            ["array", []],
+            ['array', []],
         ];
     }
 
@@ -69,7 +69,7 @@ public static function positiveMatches()
     {
         return [
             [1, 1],
-            ["michal", "michal"],
+            ['michal', 'michal'],
             [false, false],
             [6.66, 6.66],
         ];
@@ -79,7 +79,7 @@ public static function positiveCanMatches()
     {
         return [
             [1],
-            ["michal"],
+            ['michal'],
             [true],
             [false],
             [6.66],
@@ -97,10 +97,10 @@ public static function negativeCanMatches()
     public static function negativeMatchDescription()
     {
         return [
-            ["test", "norbert", "\"test\" does not match \"norbert\"."],
-            [new \stdClass,  1, "\"\\stdClass\" does not match \"1\"."],
-            [1.1, false, "\"1.1\" does not match \"false\"."],
-            [false, ['foo', 'bar'], "\"false\" does not match \"Array(2)\"."],
+            ['test', 'norbert', '"test" does not match "norbert".'],
+            [new \stdClass,  1, '"\\stdClass" does not match "1".'],
+            [1.1, false, '"1.1" does not match "false".'],
+            [false, ['foo', 'bar'], '"false" does not match "Array(2)".'],
         ];
     }
 }
diff --git a/tests/Matcher/StringMatcherTest.php b/tests/Matcher/StringMatcherTest.php
index 42a65318..f0a90ee4 100644
--- a/tests/Matcher/StringMatcherTest.php
+++ b/tests/Matcher/StringMatcherTest.php
@@ -65,26 +65,26 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@string@"]
+            ['@string@']
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            ["lorem ipsum", "@string@"],
-            ["lorem ipsum", "@string@.isNotEmpty()"],
-            ["lorem ipsum", "@string@.startsWith('lorem')"],
-            ["lorem ipsum", "@string@.endsWith('ipsum')"],
-            ["lorem ipsum dolor", "@string@.startsWith('lorem').contains('ipsum').endsWith('dolor')"],
+            ['lorem ipsum', '@string@'],
+            ['lorem ipsum', '@string@.isNotEmpty()'],
+            ['lorem ipsum', "@string@.startsWith('lorem')"],
+            ['lorem ipsum', "@string@.endsWith('ipsum')"],
+            ['lorem ipsum dolor', "@string@.startsWith('lorem').contains('ipsum').endsWith('dolor')"],
         ];
     }
 
     public static function negativeCanMatchData()
     {
         return [
-            ["@string"],
-            ["string"],
+            ['@string'],
+            ['string'],
             [1]
         ];
     }
@@ -92,19 +92,19 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            [1, "@string@"],
-            [0,  "@string@"]
+            [1, '@string@'],
+            [0,  '@string@']
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [new \stdClass,  "@string@", "object \"\\stdClass\" is not a valid string."],
-            [1.1, "@integer@", "double \"1.1\" is not a valid string."],
-            [false, "@double@", "boolean \"false\" is not a valid string."],
-            [1, "@array@", "integer \"1\" is not a valid string."],
-            ["lorem ipsum", "@array@.startsWith('ipsum')", "string \"lorem ipsum\" doesn't starts with string \"ipsum\"."]
+            [new \stdClass,  '@string@', 'object "\\stdClass" is not a valid string.'],
+            [1.1, '@integer@', 'double "1.1" is not a valid string.'],
+            [false, '@double@', 'boolean "false" is not a valid string.'],
+            [1, '@array@', 'integer "1" is not a valid string.'],
+            ['lorem ipsum', "@array@.startsWith('ipsum')", "string \"lorem ipsum\" doesn't starts with string \"ipsum\"."]
         ];
     }
 }
diff --git a/tests/Matcher/TextMatcherTest.php b/tests/Matcher/TextMatcherTest.php
index 160e229b..7318ec9b 100644
--- a/tests/Matcher/TextMatcherTest.php
+++ b/tests/Matcher/TextMatcherTest.php
@@ -83,29 +83,29 @@ public function test_ignore_valid_xml_patterns()
 
     public function test_error_when_unsupported_type_pattern_used()
     {
-        $pattern = "lorem ipsum @null@ bla bla";
-        $value = "lorem ipsum bla bla";
+        $pattern = 'lorem ipsum @null@ bla bla';
+        $value = 'lorem ipsum bla bla';
 
         $this->assertFalse($this->matcher->match($value, $pattern));
-        $this->assertSame("Type pattern \"@null@\" is not supported by TextMatcher.", $this->matcher->getError());
+        $this->assertSame('Type pattern "@null@" is not supported by TextMatcher.', $this->matcher->getError());
     }
 
     public function matchingData()
     {
         return [
             [
-                "lorem ipsum lol lorem 24 dolorem",
-                "lorem ipsum @string@.startsWith(\"lo\") lorem @number@ dolorem",
+                'lorem ipsum lol lorem 24 dolorem',
+                'lorem ipsum @string@.startsWith("lo") lorem @number@ dolorem',
                 true
             ],
             [
-                "lorem ipsum 24 dolorem",
-                "lorem ipsum @integer@",
+                'lorem ipsum 24 dolorem',
+                'lorem ipsum @integer@',
                 false
             ],
             [
-                "/users/12345/active",
-                "/users/@integer@.greaterThan(0)/active",
+                '/users/12345/active',
+                '/users/@integer@.greaterThan(0)/active',
                 true
             ]
         ];
diff --git a/tests/Matcher/UuidMatcherTest.php b/tests/Matcher/UuidMatcherTest.php
index 31192103..86fa2357 100644
--- a/tests/Matcher/UuidMatcherTest.php
+++ b/tests/Matcher/UuidMatcherTest.php
@@ -64,26 +64,26 @@ public function test_negative_match_description($value, $pattern, $error)
     public static function positiveCanMatchData()
     {
         return [
-            ["@uuid@"],
+            ['@uuid@'],
         ];
     }
 
     public static function positiveMatchData()
     {
         return [
-            ["21627164-acb7-11e6-80f5-76304dec7eb7", "@uuid@"],
-            ["d9c04bc2-173f-2cb7-ad4e-e4ca3b2c273f", "@uuid@"],
-            ["7b368038-a5ca-3aa3-b0db-1177d1761c9e", "@uuid@"],
-            ["9f4db639-0e87-4367-9beb-d64e3f42ae18", "@uuid@"],
-            ["1f2b1a18-81a0-5685-bca7-f23022ed7c7b", "@uuid@"],
+            ['21627164-acb7-11e6-80f5-76304dec7eb7', '@uuid@'],
+            ['d9c04bc2-173f-2cb7-ad4e-e4ca3b2c273f', '@uuid@'],
+            ['7b368038-a5ca-3aa3-b0db-1177d1761c9e', '@uuid@'],
+            ['9f4db639-0e87-4367-9beb-d64e3f42ae18', '@uuid@'],
+            ['1f2b1a18-81a0-5685-bca7-f23022ed7c7b', '@uuid@'],
         ];
     }
 
     public static function negativeCanMatchData()
     {
         return [
-            ["@uuid"],
-            ["uuid"],
+            ['@uuid'],
+            ['uuid'],
             [1],
         ];
     }
@@ -91,27 +91,27 @@ public static function negativeCanMatchData()
     public static function negativeMatchData()
     {
         return [
-            [1, "@uuid@"],
-            [0, "@uuid@"],
-            ["9f4d-b639-0e87-4367-9beb-d64e3f42ae18", "@uuid@"],
-            ["9f4db639-0e87-4367-9beb-d64e3f42ae1", "@uuid@"],
-            ["9f4db639-0e87-4367-9beb-d64e3f42ae181", "@uuid@"],
-            ["9f4db6390e8743679bebd64e3f42ae18", "@uuid@"],
-            ["9f4db6390e87-4367-9beb-d64e-3f42ae18", "@uuid@"],
-            ["9f4db639-0e87-4367-9beb-d64e3f42ae1g", "@uuid@"],
-            ["9f4db639-0e87-0367-9beb-d64e3f42ae18", "@uuid@"],
+            [1, '@uuid@'],
+            [0, '@uuid@'],
+            ['9f4d-b639-0e87-4367-9beb-d64e3f42ae18', '@uuid@'],
+            ['9f4db639-0e87-4367-9beb-d64e3f42ae1', '@uuid@'],
+            ['9f4db639-0e87-4367-9beb-d64e3f42ae181', '@uuid@'],
+            ['9f4db6390e8743679bebd64e3f42ae18', '@uuid@'],
+            ['9f4db6390e87-4367-9beb-d64e-3f42ae18', '@uuid@'],
+            ['9f4db639-0e87-4367-9beb-d64e3f42ae1g', '@uuid@'],
+            ['9f4db639-0e87-0367-9beb-d64e3f42ae18', '@uuid@'],
         ];
     }
 
     public static function negativeMatchDescription()
     {
         return [
-            [new \stdClass,  "@uuid@", "object \"\\stdClass\" is not a valid UUID: not a string."],
-            [1.1, "@uuid@", "double \"1.1\" is not a valid UUID: not a string."],
-            [false, "@uuid@", "boolean \"false\" is not a valid UUID: not a string."],
-            [1, "@uuid@", "integer \"1\" is not a valid UUID: not a string."],
-            ["lorem ipsum", "@uuid@", "string \"lorem ipsum\" is not a valid UUID: invalid format."],
-            ["9f4db639-0e87-4367-9beb-d64e3f42ae1z", "@uuid@", "string \"9f4db639-0e87-4367-9beb-d64e3f42ae1z\" is not a valid UUID: invalid format."],
+            [new \stdClass,  '@uuid@', 'object "\\stdClass" is not a valid UUID: not a string.'],
+            [1.1, '@uuid@', 'double "1.1" is not a valid UUID: not a string.'],
+            [false, '@uuid@', 'boolean "false" is not a valid UUID: not a string.'],
+            [1, '@uuid@', 'integer "1" is not a valid UUID: not a string.'],
+            ['lorem ipsum', '@uuid@', 'string "lorem ipsum" is not a valid UUID: invalid format.'],
+            ['9f4db639-0e87-4367-9beb-d64e3f42ae1z', '@uuid@', 'string "9f4db639-0e87-4367-9beb-d64e3f42ae1z" is not a valid UUID: invalid format.'],
         ];
     }
 }
diff --git a/tests/Matcher/WildcardMatcherTest.php b/tests/Matcher/WildcardMatcherTest.php
index cf061a64..5703111d 100644
--- a/tests/Matcher/WildcardMatcherTest.php
+++ b/tests/Matcher/WildcardMatcherTest.php
@@ -37,11 +37,11 @@ public function test_negative_can_match()
     public static function data()
     {
         return [
-            ["@integer@"],
-            ["foobar"],
+            ['@integer@'],
+            ['foobar'],
             [true],
             [6.66],
-            [["bar"]],
+            [['bar']],
             [new \stdClass],
         ];
     }
@@ -49,8 +49,8 @@ public static function data()
     public static function positivePatterns()
     {
         return [
-            ["@*@"],
-            ["@wildcard@"],
+            ['@*@'],
+            ['@wildcard@'],
         ];
     }
 }
diff --git a/tests/MatcherTest.php b/tests/MatcherTest.php
index 5c3cf669..8e56b9cc 100644
--- a/tests/MatcherTest.php
+++ b/tests/MatcherTest.php
@@ -275,7 +275,7 @@ public function test_matcher_with_xml_including_optional_node()
 
     public function test_text_matcher()
     {
-        $value = "lorem ipsum 1234 random text";
+        $value = 'lorem ipsum 1234 random text';
         $pattern = "@string@.startsWith('lo') ipsum @number@.greaterThan(10) random text";
         $this->assertTrue($this->matcher->match($value, $pattern));
         $this->assertTrue(PHPMatcher::match($value, $pattern));
@@ -349,29 +349,29 @@ public function scalarValueExamples()
     public static function expanderExamples()
     {
         return [
-            ["lorem ipsum", "@string@.startsWith(\"lorem\")", true],
-            ["lorem ipsum", "@string@.startsWith(\"LOREM\", true)", true],
-            ["lorem ipsum", "@string@.endsWith(\"ipsum\")", true],
-            ["lorem ipsum", "@string@.endsWith(\"IPSUM\", true)", true],
-            ["lorem ipsum", "@string@.contains(\"lorem\")", true],
-            ["norbert@coduo.pl", "@string@.isEmail()", true],
-            ["lorem ipsum", "@string@.isEmail()", false],
-            ["http://coduo.pl/", "@string@.isUrl()", true],
-            ["lorem ipsum", "@string@.isUrl()", false],
-            ["2014-08-19", "@string@.isDateTime()", true],
-            [100, "@integer@.lowerThan(101).greaterThan(10)", true],
-            ["", "@string@.isNotEmpty()", false],
-            ["lorem ipsum", "@string@.isNotEmpty()", true],
-            ["", "@string@.isEmpty()", true],
-            [["foo", "bar"], "@array@.inArray(\"bar\")", true],
-            [[], "@array@.isEmpty()", true],
-            [['foo'], "@array@.isEmpty()", false],
-            [[1, 2, 3], "@array@.count(3)", true],
-            [[1, 2, 3], "@array@.count(4)", false],
-            ["lorem ipsum", "@string@.oneOf(contains(\"lorem\"), contains(\"test\"))", true],
-            ["lorem ipsum", "@string@.oneOf(contains(\"lorem\"), contains(\"test\")).endsWith(\"ipsum\")", true],
-            ["lorem ipsum", "@string@.matchRegex(\"/^lorem \\w+$/\")", true],
-            ["lorem ipsum", "@string@.matchRegex(\"/^foo/\")", false],
+            ['lorem ipsum', '@string@.startsWith("lorem")', true],
+            ['lorem ipsum', '@string@.startsWith("LOREM", true)', true],
+            ['lorem ipsum', '@string@.endsWith("ipsum")', true],
+            ['lorem ipsum', '@string@.endsWith("IPSUM", true)', true],
+            ['lorem ipsum', '@string@.contains("lorem")', true],
+            ['norbert@coduo.pl', '@string@.isEmail()', true],
+            ['lorem ipsum', '@string@.isEmail()', false],
+            ['http://coduo.pl/', '@string@.isUrl()', true],
+            ['lorem ipsum', '@string@.isUrl()', false],
+            ['2014-08-19', '@string@.isDateTime()', true],
+            [100, '@integer@.lowerThan(101).greaterThan(10)', true],
+            ['', '@string@.isNotEmpty()', false],
+            ['lorem ipsum', '@string@.isNotEmpty()', true],
+            ['', '@string@.isEmpty()', true],
+            [['foo', 'bar'], '@array@.inArray("bar")', true],
+            [[], '@array@.isEmpty()', true],
+            [['foo'], '@array@.isEmpty()', false],
+            [[1, 2, 3], '@array@.count(3)', true],
+            [[1, 2, 3], '@array@.count(4)', false],
+            ['lorem ipsum', '@string@.oneOf(contains("lorem"), contains("test"))', true],
+            ['lorem ipsum', '@string@.oneOf(contains("lorem"), contains("test")).endsWith("ipsum")', true],
+            ['lorem ipsum', '@string@.matchRegex("/^lorem \\w+$/")', true],
+            ['lorem ipsum', '@string@.matchRegex("/^foo/")', false],
             [[], ['unexistent_key' => '@array@.optional()'], true],
             [[], ['unexistent_key' => '@boolean@.optional()'], true],
             [[], ['unexistent_key' => '@double@.optional()'], true],
@@ -389,14 +389,14 @@ public static function expanderExamples()
     public static function orExamples()
     {
         return [
-            ["lorem ipsum", "@string@.startsWith(\"lorem\")||@string@.contains(\"lorem\")", true],
-            ["ipsum lorem", "@string@.startsWith(\"lorem\")||@string@.contains(\"lorem\")", true],
-            ["norbert@coduo.pl", "@string@.isEmail()||@null@", true],
-            [null, "@string@.isEmail()||@null@", true],
-            [null, "@string@.isEmail()||@null@", true],
-            ["2014-08-19", "@string@.isDateTime()||@integer@", true],
-            [null, "@integer@||@string@", false],
-            [1, "@integer@.greaterThan(10)||@string@.contains(\"10\")", false],
+            ['lorem ipsum', '@string@.startsWith("lorem")||@string@.contains("lorem")', true],
+            ['ipsum lorem', '@string@.startsWith("lorem")||@string@.contains("lorem")', true],
+            ['norbert@coduo.pl', '@string@.isEmail()||@null@', true],
+            [null, '@string@.isEmail()||@null@', true],
+            [null, '@string@.isEmail()||@null@', true],
+            ['2014-08-19', '@string@.isDateTime()||@integer@', true],
+            [null, '@integer@||@string@', false],
+            [1, '@integer@.greaterThan(10)||@string@.contains("10")', false],
         ];
     }
 
diff --git a/tests/ParserSyntaxErrorTest.php b/tests/ParserSyntaxErrorTest.php
index e5366796..7bcc8dbb 100644
--- a/tests/ParserSyntaxErrorTest.php
+++ b/tests/ParserSyntaxErrorTest.php
@@ -26,7 +26,7 @@ public function setUp()
      */
     public function test_unexpected_statement_at_type_position()
     {
-        $this->parser->getAST("not_valid_type");
+        $this->parser->getAST('not_valid_type');
     }
 
     /**
@@ -35,7 +35,7 @@ public function test_unexpected_statement_at_type_position()
      */
     public function test_unexpected_statement_instead_of_expander()
     {
-        $this->parser->getAST("@type@anything");
+        $this->parser->getAST('@type@anything');
     }
 
     /**
@@ -44,7 +44,7 @@ public function test_unexpected_statement_instead_of_expander()
      */
     public function test_end_of_string_after_opening_parenthesis()
     {
-        $this->parser->getAST("@type@.expander(");
+        $this->parser->getAST('@type@.expander(');
     }
 
     /**
@@ -53,7 +53,7 @@ public function test_end_of_string_after_opening_parenthesis()
      */
     public function test_not_argument_after_opening_parenthesis()
     {
-        $this->parser->getAST("@type@.expander(not_argument");
+        $this->parser->getAST('@type@.expander(not_argument');
     }
 
     /**
diff --git a/tests/ParserTest.php b/tests/ParserTest.php
index 7d67c6c1..dc989eb2 100644
--- a/tests/ParserTest.php
+++ b/tests/ParserTest.php
@@ -23,17 +23,17 @@ public function setUp()
 
     public function test_simple_pattern_without_expanders()
     {
-        $pattern = "@type@";
+        $pattern = '@type@';
 
-        $this->assertEquals("type", $this->parser->getAST($pattern)->getType());
+        $this->assertEquals('type', $this->parser->getAST($pattern)->getType());
         $this->assertFalse($this->parser->getAST($pattern)->hasExpanders());
     }
 
     public function test_single_expander_without_args()
     {
-        $pattern = "@type@.expander()";
+        $pattern = '@type@.expander()';
 
-        $this->assertEquals("type", $this->parser->getAST($pattern)->getType());
+        $this->assertEquals('type', $this->parser->getAST($pattern)->getType());
         $expanders = $this->parser->getAST($pattern)->getExpanders();
         $this->assertEquals('expander', $expanders[0]->getName());
         $this->assertFalse($expanders[0]->hasArguments());
@@ -42,13 +42,13 @@ public function test_single_expander_without_args()
     public function test_single_expander_with_arguments()
     {
         $pattern = "@type@.expander('arg1', 2, 2.24, \"arg3\")";
-        $this->assertEquals("type", $this->parser->getAST($pattern)->getType());
+        $this->assertEquals('type', $this->parser->getAST($pattern)->getType());
         $expanders = $this->parser->getAST($pattern)->getExpanders();
         $expectedArguments = [
-            "arg1",
+            'arg1',
             2,
             2.24,
-            "arg3"
+            'arg3'
         ];
         $this->assertEquals($expectedArguments, $expanders[0]->getArguments());
     }
@@ -63,7 +63,7 @@ public function test_many_expanders()
         ];
 
         $expanders = $this->parser->getAST($pattern)->getExpanders();
-        $this->assertEquals("type", $this->parser->getAST($pattern)->getType());
+        $this->assertEquals('type', $this->parser->getAST($pattern)->getType());
         $this->assertEquals('expander', $expanders[0]->getName());
         $this->assertEquals('expander1', $expanders[1]->getName());
         $this->assertEquals('expander', $expanders[2]->getName());
@@ -86,64 +86,64 @@ public static function expandersWithArrayArguments()
     {
         return [
             [
-                "@type@.expander({\"foo\":\"bar\"})",
-                [["foo" => "bar"]]
+                '@type@.expander({"foo":"bar"})',
+                [['foo' => 'bar']]
             ],
             [
-                "@type@.expander({1 : \"bar\"})",
-                [[1 => "bar"]]
+                '@type@.expander({1 : "bar"})',
+                [[1 => 'bar']]
             ],
             [
-                "@type@.expander({\"foo\":\"bar\"}, {\"foz\" : \"baz\"})",
-                [["foo" => "bar"], ["foz" => "baz"]]
+                '@type@.expander({"foo":"bar"}, {"foz" : "baz"})',
+                [['foo' => 'bar'], ['foz' => 'baz']]
             ],
             [
-                "@type@.expander({1 : 1})",
+                '@type@.expander({1 : 1})',
                 [[1 => 1]]
             ],
             [
-                "@type@.expander({1 : true})",
+                '@type@.expander({1 : true})',
                 [[1 => true]]
             ],
             [
-                "@type@.expander({1 : 1}, {1 : 1})",
+                '@type@.expander({1 : 1}, {1 : 1})',
                 [[1 => 1], [1 => 1]]
             ],
             [
-                "@type@.expander({1 : {\"foo\" : \"bar\"}}, {1 : 1})",
-                [[1 => ["foo" => "bar"]], [1 => 1]]
+                '@type@.expander({1 : {"foo" : "bar"}}, {1 : 1})',
+                [[1 => ['foo' => 'bar']], [1 => 1]]
             ],
             [
-                "@type@.expander({null: \"bar\"})",
-                [["" => "bar"]]
+                '@type@.expander({null: "bar"})',
+                [['' => 'bar']]
             ],
             [
-                "@type@.expander({\"foo\": null})",
-                [["foo" => null]]
+                '@type@.expander({"foo": null})',
+                [['foo' => null]]
             ],
             [
-                "@type@.expander({\"foo\" : \"bar\", \"foz\" : \"baz\"})",
-                [["foo" => "bar", "foz" => "baz"]]
+                '@type@.expander({"foo" : "bar", "foz" : "baz"})',
+                [['foo' => 'bar', 'foz' => 'baz']]
             ],
             [
-                "@type@.expander({\"foo\" : \"bar\", \"foo\" : \"baz\"})",
-                [["foo" => "baz"]]
+                '@type@.expander({"foo" : "bar", "foo" : "baz"})',
+                [['foo' => 'baz']]
             ],
             [
-                "@type@.expander({\"foo\" : \"bar\", 1 : {\"first\" : 1, \"second\" : 2}})",
-                [["foo" => "bar", 1 => ["first" => 1, "second" => 2]]]
+                '@type@.expander({"foo" : "bar", 1 : {"first" : 1, "second" : 2}})',
+                [['foo' => 'bar', 1 => ['first' => 1, 'second' => 2]]]
             ]
         ];
     }
 
     public function test_expanders_that_takes_other_expanders_as_arguments()
     {
-        $pattern = "@type@.expander(expander(\"test\"), expander(1))";
+        $pattern = '@type@.expander(expander("test"), expander(1))';
         $expanders = $this->parser->getAST($pattern)->getExpanders();
 
-        $firstExpander = new Expander("expander");
-        $firstExpander->addArgument("test");
-        $secondExpander = new Expander("expander");
+        $firstExpander = new Expander('expander');
+        $firstExpander->addArgument('test');
+        $secondExpander = new Expander('expander');
         $secondExpander->addArgument(1);
 
         $this->assertEquals(