The heart of SimpleTest is a testing framework built around test case classes. These are written as extensions of base test case classes, each extended with methods that actually contain test code. Top level test scripts then invoke the run() methods on every one of these test cases in order. Each test method is written to invoke various assertions that the developer expects to be true such as assertEqual(). If the expectation is correct, then a successful result is dispatched to the observing test reporter, but any failure triggers an alert and a description of the mismatch.
A test case looks like this...
<?php
class MyTestCase extends UnitTestCase {
function testLog() {
$log = &new Log('my.log');
$log->message('Hello');
$this->assertTrue(file_exists('my.log'));
}
}
?>
These tools are designed for the developer. Tests are written in the PHP language itself more or less as the application itself is built. The advantage of using PHP itself as the testing language is that there are no new languages to learn, testing can start straight away, and the developer can test any part of the code. Basically, all parts that can be accessed by the application code can also be accessed by the test code if they are in the same language.
The simplest type of test case is the UnitTestCase. This class of test case includes standard tests for equality, references and pattern matching. All these test the typical expectations of what you would expect the result of a function or method to be. This is by far the most common type of test in the daily routine of development, making up about 95% of test cases.
The top level task of a web application though is not to produce correct output from its methods and objects, but to generate web pages. The WebTestCase class tests web pages. It simulates a web browser requesting a page, complete with cookies, proxies, secure connections, authentication, forms, frames and most navigation elements. With this type of test case, the developer can assert that information is present in the page and that forms and sessions are handled correctly.
A WebTestCase looks like this...
<?php
class MySiteTest extends WebTestCase {
function testHomePage() {
$this->get('http://www.my-site.com/index.php');
$this->assertTitle('My Home Page');
$this->clickLink('Contact');
$this->assertTitle('Contact me');
$this->assertWantedPattern('/Email me at/');
}
}
?>
The following is a very rough outline of past and future features and their expected point of release. I am afraid it is liable to change without warning as meeting the milestones rather depends on time available. Green stuff has been coded, but not necessarily released yet. If you have a pressing need for a green but unreleased feature then you should check-out the code from Sourceforge CVS directly.
| Feature | Description | Release |
|---|---|---|
| Unit test case | Core test case class and assertions | 1.0 |
| Html display | Simplest possible display | 1.0 |
| Autoloading of test cases | Reading a file with test cases and loading them into a group test automatically | 1.0 |
| Mock objects | Objects capable of simulating other objects removing test dependencies | 1.0 |
| Web test case | Allows link following and title tag matching | 1.0 |
| Partial mocks | Mocking parts of a class for testing less than a class or for complex simulations | 1.0 |
| Web cookie handling | Correct handling of cookies when fetching pages | 1.0 |
| Following redirects | Page fetching automatically follows 300 redirects | 1.0 |
| Form parsing | Ability to submit simple forms and read default form values | 1.0 |
| Command line interface | Test display without the need of a web browser | 1.0 |
| Exposure of expectation classes | Can create precise tests with mocks as well as test cases | 1.0 |
| XML output and parsing | Allows multi host testing and the integration of acceptance testing extensions | 1.0 |
| Browser component | Exposure of lower level web browser interface for more detailed test cases | 1.0 |
| HTTP authentication | Fetching protected web pages with basic authentication only | 1.0 |
| SSL support | Can connect to https: pages | 1.0 |
| Proxy support | Can connect via. common proxies | 1.0 |
| Frames support | Handling of frames in web test cases | 1.0 |
| File upload testing | Can simulate the input type file tag | 1.0.1 |
| Mocking interfaces | Can generate mock objects to interfaces as well as classes and class interfaces are carried for type hints | 1.0.1 |
| Reporting machinery enhancements | Improved message passing for better cooperation with IDEs | 1.1 |
| Localisation | Messages abstracted and code generated from XML | 1.1 |
| Testing exceptions | Similar to testing PHP errors | 1.1 |
| IFrame support | Reads IFrame content that can be refreshed | 1.1 |
| Improved mock interface | More compact way of expressing mocks | 2.0 |
| HTML table assertions | Can match table elements to numerical assertions | 2.0 |
| XPath searching of HTML elements | More flexible content matching | 2.0 |
| Alternate HTML parsers | Can detect compiled parsers for performance improvements | 2.0 |
| Javascript suport | Use of PECL module to add Javascript | 3.0 |
Process is at least as important as tools. The type of process that makes the heaviest use of a developer's testing tool is of course Extreme Programming. This is one of the Agile Methodologies which combine various practices to "flatten the cost curve" of software development. More extreme still is Test Driven Development, where you very strictly adhere to the rule of no coding until you have a test. If you're more of a planner or believe that experience trumps evolution, you may prefer the RUP approach. I haven't tried it, but even I can see that you will need test tools (see figure 9).
Most unit testers clone JUnit to some degree, as far as the interface at least. There is a wealth of information on the JUnit site including the FAQ which contains plenty of general advice on testing. Once you get bitten by the bug you will certainly appreciate the phrase test infected coined by Eric Gamma. If you are still reviewing which unit tester to use the main choices are PHPUnit and Pear PHP::PHPUnit. They currently lack a lot of features found in SimpleTest, but the PEAR version at least has been upgraded for PHP5 and is recommended if you are porting existing JUnit test cases.
Library writers don't seem to ship tests with their code very often which is a shame. Library code that includes tests can be more safely refactored and the test code can act as additional documentation in a fairly standard form. This can save trawling the source code for clues when problems occour, especially when upgrading such a library. Libraries using SimpleTest for their unit testing include WACT and PEAR::XML_HTMLSax.
There is currently a sad lack of material on mock objects, which is a shame as unit testing without them is a lot more work. The original mock objects paper is very Java focused, but still worth a read. As a new technology there are plenty of discussions and debate on how to use mocks, often on Wikis such as Extreme Tuesday or www.mockobjects.com or the original C2 Wiki. Injecting mocks into a class is the main area of debate for which this paper on IBM makes a good starting point.
There are plenty of web testing tools, but most are written in Java and tutorials and advice are rather thin on the ground. The only hope is to look at the documentation for HTTPUnit, HTMLUnit or JWebUnit and hope for clues. There are some XML driven test frameworks, but again most require Java to run. As SimpleTest does not support JavaScript you would probably have to look at these tools anyway if you have highly dynamic pages.