invoker.php
public function invoke($method)
    {
        $this->test_case->setUp();
        $this->test_case->$method();
        $this->test_case->tearDown();
    }
public function invoke($method)
    {
        $this->test_case->setUp();
        $this->test_case->$method();
        $this->test_case->tearDown();
    }
Invokes a test method and buffered with setUp() and tearDown() calls.

@param string $method    Test method to call.