Fix 5.3 build

Author: Seldaek

tests/Composer/Installers/Test/TestCase.php

@@ -63,6 +63,8 @@ protected function ensureDirectoryExistsAndClear($directory)
         mkdir($directory, 0777, true);
     }
 
+    // polyfills for old phpunit for 5.3 support
+
     /**
      * @param string      $exception
      * @param string|null $message
@@ -84,4 +86,17 @@ public function setExpectedException($exception, $message = null, $code = null)
             parent::setExpectedException($exception, $message, $code);
         }
     }
+
+    /**
+     * @param string $needle
+     * @param string $haystack
+     * @param string $message
+     *
+     * @return void
+     */
+    public static function assertStringContainsString($needle, $haystack, $message = '')
+    {
+        $constraint = new StringContains($needle, false);
+        static::assertThat($haystack, $constraint, $message);
+    }
 }