Merge pull request #11 from faissaloux/tobenegative

`toBeNegative()`

README.md

@@ -41,3 +41,9 @@ This plugin afford math related expectations.
     expect(1)->toBePositive();
     expect(-2)->not->toBePositive();
 ```
+
+#### `toBeNegative()`
+```php
+    expect(-1)->toBeNegative();
+    expect(2)->not->toBeNegative();
+```

src/Expectation.php

@@ -47,6 +47,14 @@ public function toBePositive(): PestExpectation
         return expect($this->value > 0)->toBeTrue();
     }
 
+    /**
+     * @return PestExpectation<TValue>
+     */
+    public function toBeNegative(): PestExpectation
+    {
+        return expect($this->value < 0)->toBeTrue();
+    }
+
     /**
      * @return PestExpectation<TValue>
      */

tests/toBeNegative.php

@@ -0,0 +1,19 @@
+<?php
+
+use PHPUnit\Framework\ExpectationFailedException;
+
+it('passes', function (int $number): void {
+    expect($number)->toBeNegative();
+})->with([-1, -2, -3, -4, -5, -6]);
+
+it('passes not', function (int $number): void {
+    expect($number)->not->toBeNegative();
+})->with([1, 2, 3, 4, 5, 6]);
+
+test('failures', function (): void {
+    expect(0)->toBeNegative();
+})->throws(ExpectationFailedException::class);
+
+test('failures not', function (): void {
+    expect(-2)->not->toBeNegative();
+})->throws(ExpectationFailedException::class);