code: protected function extendClassCode($methods)
      {
          $code  = 'class ' . $this->mock_class . ' extends ' . $this->class . " {\n";
          $code .= "    protected \$mock;\n";
          $code .= $this->addMethodList($methods);
          $code .= "\n";
  
          $code .= "    function __construct() {\n";
          $code .= '        $this->mock = new ' . $this->mock_base . "();\n";
          $code .= "        \$this->mock->disableExpectationNameChecks();\n";
          $code .= "    }\n";
          $code .= $this->createCodeForConstructor();
          $code .= $this->chainMockReturns();
          $code .= $this->chainMockExpectations();
          $code .= $this->chainThrowMethods();
          $code .= $this->createCodeForOverridenMethods($methods);
          $code .= "}\n";
  
          return $code;
      }
docs: The extension class code as a string.
  The class composites a mock object and chains mocked methods to it.
  
  @param array $methods Mocked methods.
  
  @return string Code for a new class.