code: public function generatePartial($methods)
      {
          if (! $this->reflection->classExists($this->class)) {
              return false;
          }
          $mock_reflection = new SimpleReflection($this->mock_class);
          if ($mock_reflection->classExistsWithoutAutoload()) {
              trigger_error('Partial mock class [' . $this->mock_class . '] already exists');
  
              return false;
          }
          $code = $this->extendClassCode($methods);
  
          return eval("$code return \$code;");
      }
docs: Generates a version of a class with selected methods mocked only.
  Inherits the old class and chains the mock methods of an aggregated mock object.
  
  @param array $methods Methods to be overridden with mock versions.