Fixed prefix resolution

Author: dantleech

lib/Adapter/Composer/Psr0NameInflector.php

@@ -9,8 +9,9 @@ final class Psr0NameInflector implements NameInflector
 {
     public function inflectToRelativePath(string $prefix, ClassName $className, string $mappedPath): FilePath
     {
-        if (substr($prefix, -1) !== '\\' && $className->beginsWith($prefix)) {
-            $className = substr($className, strlen($prefix));
+        if (substr($prefix, -1) === '_' && $className->beginsWith($prefix)) {
+            $elements = explode('_', $className);
+            $className = implode('\\', $elements);
         }
 
         $relativePath = str_replace('\\', '/', $className).'.php';

tests/Integration/Composer/ComposerClassToFileTest.php

@@ -99,9 +99,16 @@ public function testPsr0Fallback()
     public function testPsr0ShortNamePrefix()
     {
         $this->loadExample('psr0-short-prefix.json');
-        $this->assertClassNameToFilePath('Twig_Extension', [ 'psr0/twig/Extension.php' ]);
+        $this->assertClassNameToFilePath('Twig_Extension', [ 'psr0/twig/Twig/Extension.php' ]);
     }
 
+    public function testPsr0ShortNamePrefix2()
+    {
+        $this->loadExample('psr0-short-prefix.json');
+        $this->assertClassNameToFilePath('Twig_Tests_Extension', [ 'psr0/twig/Twig/Tests/Extension.php' ]);
+    }
+
+
     /**
      * @testdox PSR-4 fallback
      */