Question

When testing with phpunit, I want to assert a function call:

Given a Class:

Class TimeWrapper {
  public function time() {
    return time();
  }
}

And Its unittest:

Class TimeWrapperTest extends PHPUnit_FrameworkTestCase {
  public function testTime() {
    //Pseudocode as example of a possible solution:
    $this->assertCallsFunction("time");
  }
}

I am specifically looking for a way to test calling of global functions.

FWIW: with rspec, I use Message Expectations. I am looking to achieve something similar, or exactly similar in PHPUnit.

Answer 1

If the goal is to verify that TimeWrapper calls the built-in PHP function time, you’ll need to use the runkit extension. This will allow you to replace the built-in function with your own version that will record the call. You’ll need to enable the runkit.internal_override setting in php.ini to allow you to rename internal functions.

class TimeWrapperTest extends PHPUnit_Framework_TestCase {
    static $calledTime;

    function setUp() {
        self::$calledTime = false;
    }

    function testTimeGetsCalled() {
        $fixture = new TimeWrapper;
        try {
            runkit_function_rename('time', 'old_time');
            runkit_function_rename('new_time', 'time');
            $time = $fixture->time();
            self::assertTrue('Called time()', $calledTime);
        }
        catch (Exception $e) {
            // PHP lacks finally, but must make sure to revert time() for other test
        }
        runkit_function_rename('time', 'new_time');
        runkit_function_rename('old_time', 'time');
        if ($e) throw $e;
    }
}

function new_time() {
    TimeWrapperTest::$calledTime = true;
    return old_time();
}

If you cannot use the extension or just want to avoid that kind of trickery, you could modify TimeWrapper to allow you to override the function that gets called at runtime.

class TimeWrapper {
    private $function;

    public function __construct($function = 'time') {
        $this->function = $function;
    }

    public function time() {
        return call_user_func($this->function);
    }
}

Use the test case above without the calls to runkit_function_rename and pass new_time to the TimeWrapper constructor. The downside here is that you’ll pay a (probably tiny) performance penalty in production on each call to TimeWrapper::time.