Allow ClassSet to use several root dirs

This way we can specify just the directories we want it to scan,
as opposed to include all dirs in the root and then
excluding all dirs we don't want in the set.

src/ClassSet.php

@@ -7,15 +7,15 @@
 
 class ClassSet implements \IteratorAggregate
 {
-    /** @var string */
-    private $directory;
+    /** @var string[] */
+    private $directoryList;
 
     /** @var array */
     private $exclude;
 
-    private function __construct(string $directory)
+    private function __construct(string ...$directoryList)
     {
-        $this->directory = $directory;
+        $this->directoryList = $directoryList;
         $this->exclude = [];
     }
 
@@ -26,21 +26,21 @@ public function excludePath(string $pattern): self
         return $this;
     }
 
-    public static function fromDir(string $directory): self
+    public static function fromDir(string ...$directoryList): self
     {
-        return new self($directory);
+        return new self(...$directoryList);
     }
 
     public function getDir(): string
     {
-        return $this->directory;
+        return implode(', ', $this->directoryList);
     }
 
     public function getIterator(): \Traversable
     {
         $finder = (new Finder())
             ->files()
-            ->in($this->directory)
+            ->in($this->directoryList)
             ->name('*.php')
             ->sortByName()
             ->followLinks()

tests/Unit/ClassSetTest.php

@@ -5,11 +5,37 @@
 namespace Arkitect\Tests\Unit;
 
 use Arkitect\ClassSet;
+use Arkitect\MultipleDirClassSet;
 use org\bovigo\vfs\vfsStream;
 use PHPUnit\Framework\TestCase;
+use SplFileInfo;
 
 class ClassSetTest extends TestCase
 {
+    public function test_can_exclude_files_or_directories_from_multiple_dir_class_set(): void
+    {
+        $path = $this->createMvcProjectStructure();
+
+        $set = MultipleDirClassSet::fromDir($path . '/Controller', $path . '/Model')
+            ->excludePath("Repository");
+
+        $expected = [
+            $path . '/Controller/CatalogController.php',
+            $path . '/Controller/Foo.php',
+            $path . '/Controller/ProductsController.php',
+            $path . '/Controller/UserController.php',
+            $path . '/Controller/YieldController.php',
+            $path . '/Model/Catalog.php',
+            $path . '/Model/Products.php',
+            $path . '/Model/User.php',
+        ];
+        $actual = array_values(array_map(function ($item) {
+            /** @var SplFileInfo $item */
+            return $item->getPathname();
+        }, iterator_to_array($set)));
+        self::assertEquals($expected, $actual);
+    }
+
     public function test_can_exclude_files_or_directories(): void
     {
         $path = $this->createMvcProjectStructure();