Chapter 19. Extending PHPUnit

PHPUnit can be extended in various ways to make the writing of tests easier and customize the feedback you get from running tests. Here are common starting points to extend PHPUnit.

Subclass PHPUnit_Framework_TestCase

Write custom assertions and utility methods in an abstract subclass of PHPUnit_Framework_TestCase and derive your test case classes from that class. This is one of the easiest ways to extend PHPUnit.

Write custom assertions

When writing custom assertions it is the best practice to follow how PHPUnit's own assertions are implemented. As you can see in Example 19.1, the assertTrue() method is just a wrapper around the isTrue() and assertThat() methods: isTrue() creates a matcher object that is passed on to assertThat() for evaluation.

Example 19.1: The assertTrue() and isTrue() methods of the PHPUnit_Framework_Assert class

<?php
abstract class PHPUnit_Framework_Assert
{
    // ...
 
    /**
     * Asserts that a condition is true.
     *
     * @param  boolean $condition
     * @param  string  $message
     * @throws PHPUnit_Framework_AssertionFailedError
     */
    public static function assertTrue($condition, $message = '')
    {
        self::assertThat($condition, self::isTrue(), $message);
    }
 
    // ...
 
    /**
     * Returns a PHPUnit_Framework_Constraint_IsTrue matcher object.
     *
     * @return PHPUnit_Framework_Constraint_IsTrue
     * @since  Method available since Release 3.3.0
     */
    public static function isTrue()
    {
        return new PHPUnit_Framework_Constraint_IsTrue;
    }
 
    // ...
}?>

Example 19.2 shows how PHPUnit_Framework_Constraint_IsTrue extends the abstract base class for matcher objects (or constraints), PHPUnit_Framework_Constraint.

Example 19.2: The PHPUnit_Framework_Constraint_IsTrue class

<?php
class PHPUnit_Framework_Constraint_IsTrue extends PHPUnit_Framework_Constraint
{
    /**
     * Evaluates the constraint for parameter $other. Returns TRUE if the
     * constraint is met, FALSE otherwise.
     *
     * @param mixed $other Value or object to evaluate.
     * @return bool
     */
    public function evaluate($other)
    {
        return $other === TRUE;
    }
 
    /**
     * Returns a string representation of the constraint.
     *
     * @return string
     */
    public function toString()
    {
        return 'is true';
    }
}?>

The effort of implementing the assertTrue() and isTrue() methods as well as the PHPUnit_Framework_Constraint_IsTrue class yields the benefit that assertThat() automatically takes care of evaluating the assertion and bookkeeping tasks such as counting it for statistics. Furthermore, the isTrue() method can be used as a matcher when configuring mock objects.

Implement PHPUnit_Framework_TestListener

Example 19.3 shows a simple implementation of the PHPUnit_Framework_TestListener interface.

Example 19.3: A simple test listener

<?php
class SimpleTestListener implements PHPUnit_Framework_TestListener
{
    public function addError(PHPUnit_Framework_Test $test, Exception $e, $time)
    {
        printf("Error while running test '%s'.\n", $test->getName());
    }
 
    public function addFailure(PHPUnit_Framework_Test $test, PHPUnit_Framework_AssertionFailedError $e, $time)
    {
        printf("Test '%s' failed.\n", $test->getName());
    }
 
    public function addIncompleteTest(PHPUnit_Framework_Test $test, Exception $e, $time)
    {
        printf("Test '%s' is incomplete.\n", $test->getName());
    }
 
    public function addSkippedTest(PHPUnit_Framework_Test $test, Exception $e, $time)
    {
        printf("Test '%s' has been skipped.\n", $test->getName());
    }
 
    public function startTest(PHPUnit_Framework_Test $test)
    {
        printf("Test '%s' started.\n", $test->getName());
    }
 
    public function endTest(PHPUnit_Framework_Test $test, $time)
    {
        printf("Test '%s' ended.\n", $test->getName());
    }
 
    public function startTestSuite(PHPUnit_Framework_TestSuite $suite)
    {
        printf("TestSuite '%s' started.\n", $suite->getName());
    }
 
    public function endTestSuite(PHPUnit_Framework_TestSuite $suite)
    {
        printf("TestSuite '%s' ended.\n", $suite->getName());
    }
}
?>

In the section called “Test Listeners” you can see how to configure PHPUnit to attach your test listener to the test execution.

Subclass PHPUnit_Extensions_TestDecorator

You can wrap test cases or test suites in a subclass of PHPUnit_Extensions_TestDecorator and use the Decorator design pattern to perform some actions before and after the test runs.

PHPUnit ships with two concrete test decorators: PHPUnit_Extensions_RepeatedTest and PHPUnit_Extensions_TestSetup. The former is used to run a test repeatedly and only count it as a success if all iterations are successful. The latter was discussed in Chapter 6.

Example 19.4 shows a cut-down version of the PHPUnit_Extensions_RepeatedTest test decorator that illustrates how to write your own test decorators.

Example 19.4: The RepeatedTest Decorator

<?php
require_once 'PHPUnit/Extensions/TestDecorator.php';
 
class PHPUnit_Extensions_RepeatedTest extends PHPUnit_Extensions_TestDecorator
{
    private $timesRepeat = 1;
 
    public function __construct(PHPUnit_Framework_Test $test, $timesRepeat = 1)
    {
        parent::__construct($test);
 
        if (is_integer($timesRepeat) &&
            $timesRepeat >= 0) {
            $this->timesRepeat = $timesRepeat;
        }
    }
 
    public function count()
    {
        return $this->timesRepeat * $this->test->count();
    }
 
    public function run(PHPUnit_Framework_TestResult $result = NULL)
    {
        if ($result === NULL) {
            $result = $this->createResult();
        }
 
        for ($i = 0; $i < $this->timesRepeat && !$result->shouldStop(); $i++) {
            $this->test->run($result);
        }
 
        return $result;
    }
}
?>

Implement PHPUnit_Framework_Test

The PHPUnit_Framework_Test interface is narrow and easy to implement. You can write an implementation of PHPUnit_Framework_Test that is simpler than PHPUnit_Framework_TestCase and that runs data-driven tests, for instance.

Example 19.5 shows a data-driven test case class that compares values from a file with Comma-Separated Values (CSV). Each line of such a file looks like foo;bar, where the first value is the one we expect and the second value is the actual one.

Example 19.5: A data-driven test

<?php
class DataDrivenTest implements PHPUnit_Framework_Test
{
    private $lines;
 
    public function __construct($dataFile)
    {
        $this->lines = file($dataFile);
    }
 
    public function count()
    {
        return 1;
    }
 
    public function run(PHPUnit_Framework_TestResult $result = NULL)
    {
        if ($result === NULL) {
            $result = new PHPUnit_Framework_TestResult;
        }
 
        foreach ($this->lines as $line) {
            $result->startTest($this);
            PHP_Timer::start();
            $stopTime = NULL;
 
            list($expected, $actual) = explode(';', $line);
 
            try {
                PHPUnit_Framework_Assert::assertEquals(
                  trim($expected), trim($actual)
                );
            }
 
            catch (PHPUnit_Framework_AssertionFailedError $e) {
                $stopTime = PHP_Timer::stop();
                $result->addFailure($this, $e, $stopTime);
            }
 
            catch (Exception $e) {
                $stopTime = PHP_Timer::stop();
                $result->addError($this, $e, $stopTime);
            }
 
            if ($stopTime === NULL) {
                $stopTime = PHP_Timer::stop();
            }
 
            $result->endTest($this, $stopTime);
        }
 
        return $result;
    }
}
 
$test = new DataDrivenTest('data_file.csv');
$result = PHPUnit_TextUI_TestRunner::run($test);
?>

PHPUnit 3.6.0 by Sebastian Bergmann.

.F

Time: 0 seconds

There was 1 failure:

1) DataDrivenTest
Failed asserting that two strings are equal.
expected string <bar>
difference      <  x>
got string      <baz>
/home/sb/DataDrivenTest.php:32
/home/sb/DataDrivenTest.php:53

FAILURES!
Tests: 2, Failures: 1.

1. Automating Tests

2. PHPUnit's Goals

3. Installing PHPUnit

4. Writing Tests for PHPUnit

Test Dependencies

Data Providers

Testing Exceptions

Testing PHP Errors

Testing Output

Assertions