SimpleTest for PHP regression test documentation

# PHP Unit Test documentation

This page...

- Unit test cases and basic assertions.
- Extending test cases to customise them for your own project.
- Running a single case as a single script.

## Unit test cases

The core system is a regression testing framework built around test cases. A sample test case looks like this...

    class FileTestCase extends UnitTestCase {
    }

Actual tests are added as methods in the test case whose names by default start with the string "test" and when the test case is invoked all such methods are run in the order that PHP introspection finds them. As many test methods can be added as needed.

For example...

    require_once('simpletest/autorun.php');
    require_once('../classes/writer.php');

    class FileTestCase extends UnitTestCase {
        function FileTestCase() {
            $this->UnitTestCase('File test');
        }

        function setUp() {
            @unlink('../temp/test.txt');
        }

        function tearDown() {
            @unlink('../temp/test.txt');
        }

        function testCreation() {
            $writer = &new FileWriter('../temp/test.txt');
            $writer->write('Hello');
            $this->assertTrue(file_exists('../temp/test.txt'), 'File created');
        }
    }

The constructor is optional and usually omitted. Without a name, the class name is taken as the name of the test case.

Our only test method at the moment is testCreation() where we check that a file has been created by our Writer object. We could have put the unlink() code into this method as well, but by placing it in setUp() and tearDown() we can use it with other test methods that we add.

The setUp() method is run just before each and every test method. tearDown() is run just after each and every test method.

You can place some test case set up into the constructor to be run once for all the methods in the test case, but you risk test interference that way. This way is slightly slower, but it is safer. Note that if you come from a JUnit background this will not be the behaviour you are used to. JUnit surprisingly reinstantiates the test case for each test method to prevent such interference. SimpleTest requires the end user to use setUp(), but supplies additional hooks for library writers.

The means of reporting test results (see below) are by a visiting display class that is notified by various assert...() methods. Here is the full list for the UnitTestCase class, the default for SimpleTest...

assertTrue($x) | Fail if $x is false
assertFalse($x) | Fail if $x is true
assertNull($x) | Fail if $x is set
assertNotNull($x) | Fail if $x not set
assertIsA($x, $t) | Fail if $x is not the class or type $t
assertNotA($x, $t) | Fail if $x is of the class or type $t
assertEqual($x, $y) | Fail if $x == $y is false
assertNotEqual($x, $y) | Fail if $x == $y is true
assertWithinMargin($x, $y, $m) | Fail if abs($x - $y) < $m is false
assertOutsideMargin($x, $y, $m) | Fail if abs($x - $y) < $m is true
assertIdentical($x, $y) | Fail if $x == $y is false or a type mismatch
assertNotIdentical($x, $y) | Fail if $x == $y is true and types match
assertReference($x, $y) | Fail unless $x and $y are the same variable
assertClone($x, $y) | Fail unless $x and $y are identical copies
assertPattern($p, $x) | Fail unless the regex $p matches $x
assertNoPattern($p, $x) | Fail if the regex $p matches $x
expectError($x) | Fail if matching error does not occour
expectException($x) | Fail if matching exception is not thrown
ignoreException($x) | Swallows any upcoming matching exception
assert($e) | Fail on failed expectation object $e

All assertion methods can take an optional description as a last parameter. This is to label the displayed result with. If omitted a default message is sent instead, which is usually sufficient. This default message can still be embedded in your own message if you include "%s" within the string. All the assertions return true on a pass or false on failure.

Some examples...

    $variable = null;
    $this->assertNull($variable, 'Should be cleared');

...will pass and normally show no message. If you have set up the tester to display passes as well then the message will be displayed as is.

    $this->assertIdentical(0, false, 'Zero is not false [%s]');

This will fail as it performs a type check, as well as a comparison, between the two values. The "%s" part is replaced by the default error message that would have been shown if we had not supplied our own.

    $a = 1;
    $b = $a;
    $this->assertReference($a, $b);

Will fail as the variable $a is a copy of $b.

    $this->assertPattern('/hello/i', 'Hello world');

This will pass as using a case insensitive match the string hello is contained in Hello world.

    $this->expectError();
    trigger_error('Catastrophe');

Here the check catches the "Catastrophe" message without checking the text and passes. This removes the error from the queue.

    $this->expectError('Catastrophe');
    trigger_error('Catastrophe');

The next error check tests not only the existence of the error, but also the text which, here matches so another pass. If any unchecked errors are left at the end of a test method then an exception will be reported in the test.

Note that SimpleTest cannot catch compile time PHP errors.

The test cases also have some convenience methods for debugging code or extending the suite...

setUp() | Runs this before each test method
tearDown() | Runs this after each test method
pass() | Sends a test pass
fail() | Sends a test failure
error() | Sends an exception event
signal($type, $payload) | Sends a user defined message to the test reporter
dump($var) | Does a formatted print_r() for quick and dirty debugging

## Extending test cases

Of course additional test methods can be added to create specific types of test case, so as to extend framework...

    require_once('simpletest/autorun.php');

    class FileTester extends UnitTestCase {
        function FileTester($name = false) {
            $this->UnitTestCase($name);
        }

        function assertFileExists($filename, $message = '%s') {
            $this->assertTrue(
                    file_exists($filename),
                    sprintf($message, 'File [$filename] existence check'));
        }
    }

Here the SimpleTest library is held in a folder called simpletest that is local. Substitute your own path for this.

To prevent this test case being run accidently, it is advisable to mark it as abstract.

Alternatively you could add a SimpleTestOptions::ignore('FileTester'); directive in your code.

This new case can be now be inherited just like a normal test case...

    class FileTestCase extends FileTester {

        function setUp() {
            @unlink('../temp/test.txt');
        }

        function tearDown() {
            @unlink('../temp/test.txt');
        }

        function testCreation() {
            $writer = &new FileWriter('../temp/test.txt');
            $writer->write('Hello');
            $this->assertFileExists('../temp/test.txt');
        }
    }

If you want a test case that does not have all of the UnitTestCase assertions, only your own and a few basics, you need to extend the SimpleTestCase class instead. It is found in simple_test.php rather than unit_tester.php. See later if you want to incorporate other unit tester's test cases in your test suites.

## Running a single test case

You won't often run single test cases except when bashing away at a module that is having difficulty, and you don't want to upset the main test suite. With autorun no particular scaffolding is needed, just launch your particular test file and you're ready to go.

You can even decide which reporter (for example, TextReporter or HtmlReporter) you prefer for a specific file when launched on its own...

    <?php
    require_once('simpletest/autorun.php');
    SimpleTest :: prefer(new TextReporter());
    require_once('../classes/writer.php');

    class FileTestCase extends UnitTestCase {
        ...
    }
    ?>

This script will run as is, but of course will output zero passes and zero failures until test methods are added.
References and related information...

- SimpleTest project page on SourceForge.
- SimpleTest download page on LastCraft.
- Full API for SimpleTest from the PHPDoc.

Copyright
Marcus Baker 2006