PHPUnit tests succeed failing

November 7, 2014 2-minute read

Asserting that a test should fail in PHPUnit.

The problem

In the process of developing the function mocker I need to verify that a certain test will fail.
Take this one for example:

/**
 * @test
 * it should allow setting times the mocked function should be called and fail when called less times
 */
function it_should_allow_setting_times_the_mocked_function_should_be_called_and_fail_when_called_less_times() {
    FunctionMocker::mock( __NAMESPACE__ . '\someFunction' )->shouldBeCalledTimes( 3 );

    someFunction();
    someFunction();

    // explicit call, should not happen            
    MockCallLogger::tearDown();
}

I’m expecting someFunction to be called 3 times and it’s instead called just 2 times, the mock object should assert the failure of the test and I want to verify it. Since the tool is meant to be used in conjunction with PHPUnit the expected failure sent by the subject under test will make the test fail Not the expected result.

A quick solution

Using PHPUnit annotations solving the problems is a one liner:

/**
 * @test
 * it should allow setting times the mocked function should be called and fail when called less times
 * @expectedException \PHPUnit_Framework_AssertionFailedError
 */
function it_should_allow_setting_times_the_mocked_function_should_be_called_and_fail_when_called_less_times() {
    FunctionMocker::mock( __NAMESPACE__ . '\someFunction' )->shouldBeCalledTimes( 3 );

    someFunction();
    someFunction();

    // explicit call, should not happen            
    MockCallLogger::tearDown();
}

I’ve added the @expectedException annotation expecting just the type of exception the PHPUnit_Framework_Assert::fail method will raise; that’s the method I’m using to make the mock expectations fail.