SimpleTest for PHP regression test documentation

# PHP Unit Test documentation

## 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 {
    }

If no test name is supplied when chaining the constructor then the class name will be taken instead. This will be the name displayed in the test results.

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('../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 inteference 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 $y are the same variable
assertCopy($x, $y) | Fail if $x and $y are the same variable
assertPattern($p, $x) | Fail unless the regex $p matches $x
assertNoPattern($p, $x) | Fail if the regex $p matches $x
assertNoErrors() | Fail if any PHP error occoured
assertError($x) | Fail if no PHP error or incorrect message/expectation
assertExpectation($e) | Fail on failed expectation object

All assertion methods can take an optional description 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. This also allows us to nest test messages.

    $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.

    trigger_error('Disaster');
    trigger_error('Catastrophe');
    $this->assertError();
    $this->assertError('Catastrophe');
    $this->assertNoErrors();

This one takes some explanation as in fact they all pass!

PHP errors in SimpleTest are trapped and placed in a queue. Here the first error check catches the "Disaster" message without checking the text and passes. This removes the error from the queue. The next error check tests not only the existence of the error, but also the text which here matches so another pass. With the queue now empty the last test will pass as well. 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
sendMessage() | Sends a status message to those displays that support it
signal($type, $payload) | Sends a user defined message to the test reporter
dump($var) | Does a formatted print_r() for quick and dirty debugging
swallowErrors() | Clears the error queue

## Extending test cases

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

    require_once('simpletest/unit_tester.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.

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 assertTrue(), 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. Here is the scaffolding needed to run the a lone test case...

    <?php
        require_once('simpletest/unit_tester.php');
        require_once('simpletest/reporter.php');
        require_once('../classes/writer.php');

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

        $test = &new FileTestCase();
        $test->run(new HtmlReporter());
    ?>

This script will run as is, but will output zero passes and zero failures until test methods are added.
Copyright
Marcus Baker, Jason Sweat, Perrick Penet 2004