fix(discovery): support PSR-4 paths defined as arrays in composer.json

Author: nayleen

tests/Integration/Core/ComposerTest.php

@@ -164,4 +164,40 @@ public function dev_namespaces(): void
         $this->assertSame('Foo\\', $composer->devNamespaces[0]->namespace);
         $this->assertSame('foo/', $composer->devNamespaces[0]->path);
     }
+
+    #[Test]
+    public function supports_psr4_paths_as_array(): void
+    {
+        $composer = $this->initializeComposer([
+            'autoload' => [
+                'psr-4' => [
+                    'App\\' => 'src/',
+                    'Other\\' => ['other/src/', 'other/lib/'],
+                ],
+            ],
+            'autoload-dev' => [
+                'psr-4' => [
+                    'Tests\\' => ['tests/', 'spec/'],
+                ],
+            ],
+        ]);
+
+        $this->assertSame('App\\', $composer->mainNamespace->namespace);
+        $this->assertSame('src/', $composer->mainNamespace->path);
+
+        $this->assertCount(3, $composer->namespaces);
+        $this->assertSame('App\\', $composer->namespaces[0]->namespace);
+        $this->assertSame('src/', $composer->namespaces[0]->path);
+        $this->assertSame('Other\\', $composer->namespaces[1]->namespace);
+        $this->assertSame('other/src/', $composer->namespaces[1]->path);
+        $this->assertSame('Other\\', $composer->namespaces[2]->namespace);
+        $this->assertSame('other/lib/', $composer->namespaces[2]->path);
+
+        $this->assertCount(2, $composer->devNamespaces);
+        // sorting is based on path length, putting spec/ before tests/
+        $this->assertSame('Tests\\', $composer->devNamespaces[0]->namespace);
+        $this->assertSame('spec/', $composer->devNamespaces[0]->path);
+        $this->assertSame('Tests\\', $composer->devNamespaces[1]->namespace);
+        $this->assertSame('tests/', $composer->devNamespaces[1]->path);
+    }
 }