477 lines
18 KiB
HTML
477 lines
18 KiB
HTML
<html>
|
|
<head>
|
|
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
|
|
<title>
|
|
Extending the SimpleTest unit tester with additional expectation classes
|
|
</title>
|
|
<link rel="stylesheet" type="text/css" href="docs.css" title="Styles">
|
|
</head>
|
|
<body>
|
|
<div class="menu_back"><div class="menu">
|
|
<a href="index.html">SimpleTest</a>
|
|
|
|
|
<a href="overview.html">Overview</a>
|
|
|
|
|
<a href="unit_test_documentation.html">Unit tester</a>
|
|
|
|
|
<a href="group_test_documentation.html">Group tests</a>
|
|
|
|
|
<a href="mock_objects_documentation.html">Mock objects</a>
|
|
|
|
|
<a href="partial_mocks_documentation.html">Partial mocks</a>
|
|
|
|
|
<a href="reporter_documentation.html">Reporting</a>
|
|
|
|
|
<span class="chosen">Expectations</span>
|
|
|
|
|
<a href="web_tester_documentation.html">Web tester</a>
|
|
|
|
|
<a href="form_testing_documentation.html">Testing forms</a>
|
|
|
|
|
<a href="authentication_documentation.html">Authentication</a>
|
|
|
|
|
<a href="browser_documentation.html">Scriptable browser</a>
|
|
</div></div>
|
|
<h1>Expectation documentation</h1>
|
|
This page...
|
|
<ul>
|
|
<li>
|
|
Using expectations for
|
|
<a href="#mock">more precise testing with mock objects</a>
|
|
</li>
|
|
<li>
|
|
<a href="#behaviour">Changing mock object behaviour</a> with expectations
|
|
</li>
|
|
<li>
|
|
<a href="#extending">Extending the expectations</a>
|
|
</li>
|
|
<li>
|
|
Underneath SimpleTest <a href="#unit">uses expectation classes</a>
|
|
</li>
|
|
</ul>
|
|
<div class="content">
|
|
<h2>
|
|
<a class="target" name="mock"></a>More control over mock objects</h2>
|
|
<p>
|
|
The default behaviour of the
|
|
<a href="mock_objects_documentation.html">mock objects</a>
|
|
in
|
|
<a href="http://sourceforge.net/projects/simpletest/">SimpleTest</a>
|
|
is either an identical match on the argument or to allow any argument at all.
|
|
For almost all tests this is sufficient.
|
|
Sometimes, though, you want to weaken a test case.
|
|
</p>
|
|
<p>
|
|
One place where a test can be too tightly coupled is with
|
|
text matching.
|
|
Suppose we have a component that outputs a helpful error
|
|
message when something goes wrong.
|
|
You want to test that the correct error was sent, but the actual
|
|
text may be rather long.
|
|
If you test for the text exactly, then every time the exact wording
|
|
of the message changes, you will have to go back and edit the test suite.
|
|
</p>
|
|
<p>
|
|
For example, suppose we have a news service that has failed
|
|
to connect to its remote source.
|
|
<pre>
|
|
<strong>class NewsService {
|
|
...
|
|
function publish($writer) {
|
|
if (! $this->isConnected()) {
|
|
$writer->write('Cannot connect to news service "' .
|
|
$this->_name . '" at this time. ' .
|
|
'Please try again later.');
|
|
}
|
|
...
|
|
}
|
|
}</strong>
|
|
</pre>
|
|
Here it is sending its content to a
|
|
<span class="new_code">Writer</span> class.
|
|
We could test this behaviour with a
|
|
<span class="new_code">MockWriter</span> like so...
|
|
<pre>
|
|
class TestOfNewsService extends UnitTestCase {
|
|
...
|
|
function testConnectionFailure() {<strong>
|
|
$writer = new MockWriter();
|
|
$writer->expectOnce('write', array(
|
|
'Cannot connect to news service ' .
|
|
'"BBC News" at this time. ' .
|
|
'Please try again later.'));
|
|
|
|
$service = new NewsService('BBC News');
|
|
$service->publish($writer);</strong>
|
|
}
|
|
}
|
|
</pre>
|
|
This is a good example of a brittle test.
|
|
If we decide to add additional instructions, such as
|
|
suggesting an alternative news source, we will break
|
|
our tests even though no underlying functionality
|
|
has been altered.
|
|
</p>
|
|
<p>
|
|
To get around this, we would like to do a regular expression
|
|
test rather than an exact match.
|
|
We can actually do this with...
|
|
<pre>
|
|
class TestOfNewsService extends UnitTestCase {
|
|
...
|
|
function testConnectionFailure() {
|
|
$writer = new MockWriter();<strong>
|
|
$writer->expectOnce(
|
|
'write',
|
|
array(new PatternExpectation('/cannot connect/i')));</strong>
|
|
|
|
$service = new NewsService('BBC News');
|
|
$service->publish($writer);
|
|
}
|
|
}
|
|
</pre>
|
|
Instead of passing in the expected parameter to the
|
|
<span class="new_code">MockWriter</span> we pass an
|
|
expectation class called
|
|
<span class="new_code">PatternExpectation</span>.
|
|
The mock object is smart enough to recognise this as special
|
|
and to treat it differently.
|
|
Rather than simply comparing the incoming argument to this
|
|
object, it uses the expectation object itself to
|
|
perform the test.
|
|
</p>
|
|
<p>
|
|
The <span class="new_code">PatternExpectation</span> takes
|
|
the regular expression to match in its constructor.
|
|
Whenever a comparison is made by the <span class="new_code">MockWriter</span>
|
|
against this expectation class, it will do a
|
|
<span class="new_code">preg_match()</span> with this pattern.
|
|
With our test case above, as long as "cannot connect"
|
|
appears in the text of the string, the mock will issue a pass
|
|
to the unit tester.
|
|
The rest of the text does not matter.
|
|
</p>
|
|
<p>
|
|
The possible expectation classes are...
|
|
<table><tbody>
|
|
<tr>
|
|
<td><span class="new_code">AnythingExpectation</span></td>
|
|
<td>Will always match</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">EqualExpectation</span></td>
|
|
<td>An equality, rather than the stronger identity comparison</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">NotEqualExpectation</span></td>
|
|
<td>An inequality comparison</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">IndenticalExpectation</span></td>
|
|
<td>The default mock object check which must match exactly</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">NotIndenticalExpectation</span></td>
|
|
<td>Inverts the mock object logic</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">WithinMarginExpectation</span></td>
|
|
<td>Compares a value to within a margin</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">OutsideMarginExpectation</span></td>
|
|
<td>Checks that a value is out side the margin</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">PatternExpectation</span></td>
|
|
<td>Uses a Perl Regex to match a string</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">NoPatternExpectation</span></td>
|
|
<td>Passes only if failing a Perl Regex</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">IsAExpectation</span></td>
|
|
<td>Checks the type or class name only</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">NotAExpectation</span></td>
|
|
<td>Opposite of the <span class="new_code">IsAExpectation</span>
|
|
</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">MethodExistsExpectation</span></td>
|
|
<td>Checks a method is available on an object</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">TrueExpectation</span></td>
|
|
<td>Accepts any PHP variable that evaluates to true</td>
|
|
</tr>
|
|
<tr>
|
|
<td><span class="new_code">FalseExpectation</span></td>
|
|
<td>Accepts any PHP variable that evaluates to false</td>
|
|
</tr>
|
|
</tbody></table>
|
|
Most take the expected value in the constructor.
|
|
The exceptions are the pattern matchers, which take a regular expression,
|
|
and the <span class="new_code">IsAExpectation</span> and <span class="new_code">NotAExpectation</span> which takes a type
|
|
or class name as a string.
|
|
</p>
|
|
<p>
|
|
Some examples...
|
|
</p>
|
|
<p>
|
|
<pre>
|
|
$mock->expectOnce('method', array(new IdenticalExpectation(14)));
|
|
</pre>
|
|
This is the same as <span class="new_code">$mock->expectOnce('method', array(14))</span>.
|
|
<pre>
|
|
$mock->expectOnce('method', array(new EqualExpectation(14)));
|
|
</pre>
|
|
This is different from the previous version in that the string
|
|
<span class="new_code">"14"</span> as a parameter will also pass.
|
|
Sometimes the additional type checks of SimpleTest are too restrictive.
|
|
<pre>
|
|
$mock->expectOnce('method', array(new AnythingExpectation(14)));
|
|
</pre>
|
|
This is the same as <span class="new_code">$mock->expectOnce('method', array('*'))</span>.
|
|
<pre>
|
|
$mock->expectOnce('method', array(new IdenticalExpectation('*')));
|
|
</pre>
|
|
This is handy if you want to assert a literal <span class="new_code">"*"</span>.
|
|
<pre>
|
|
new NotIdenticalExpectation(14)
|
|
</pre>
|
|
This matches on anything other than integer 14.
|
|
Even the string <span class="new_code">"14"</span> would pass.
|
|
<pre>
|
|
new WithinMarginExpectation(14.0, 0.001)
|
|
</pre>
|
|
This will accept any value from 13.999 to 14.001 inclusive.
|
|
</p>
|
|
|
|
<h2>
|
|
<a class="target" name="behaviour"></a>Using expectations to control stubs</h2>
|
|
<p>
|
|
The expectation classes can be used not just for sending assertions
|
|
from mock objects, but also for selecting behaviour for the
|
|
<a href="mock_objects_documentation.html">mock objects</a>.
|
|
Anywhere a list of arguments is given, a list of expectation objects
|
|
can be inserted instead.
|
|
</p>
|
|
<p>
|
|
Suppose we want a mock authorisation server to simulate a successful login,
|
|
but only if it receives a valid session object.
|
|
We can do this as follows...
|
|
<pre>
|
|
Mock::generate('Authorisation');
|
|
<strong>
|
|
$authorisation = new MockAuthorisation();
|
|
$authorisation->returns(
|
|
'isAllowed',
|
|
true,
|
|
array(new IsAExpectation('Session', 'Must be a session')));
|
|
$authorisation->returns('isAllowed', false);</strong>
|
|
</pre>
|
|
We have set the default mock behaviour to return false when
|
|
<span class="new_code">isAllowed</span> is called.
|
|
When we call the method with a single parameter that
|
|
is a <span class="new_code">Session</span> object, it will return true.
|
|
We have also added a second parameter as a message.
|
|
This will be displayed as part of the mock object
|
|
failure message if this expectation is the cause of
|
|
a failure.
|
|
</p>
|
|
<p>
|
|
This kind of sophistication is rarely useful, but is included for
|
|
completeness.
|
|
</p>
|
|
|
|
<h2>
|
|
<a class="target" name="extending"></a>Creating your own expectations</h2>
|
|
<p>
|
|
The expectation classes have a very simple structure.
|
|
So simple that it is easy to create your own versions for
|
|
commonly used test logic.
|
|
</p>
|
|
<p>
|
|
As an example here is the creation of a class to test for
|
|
valid IP addresses.
|
|
In order to work correctly with the stubs and mocks the new
|
|
expectation class should extend
|
|
<span class="new_code">SimpleExpectation</span> or further extend a subclass...
|
|
<pre>
|
|
<strong>class ValidIp extends SimpleExpectation {
|
|
|
|
function test($ip) {
|
|
return (ip2long($ip) != -1);
|
|
}
|
|
|
|
function testMessage($ip) {
|
|
return "Address [$ip] should be a valid IP address";
|
|
}
|
|
}</strong>
|
|
</pre>
|
|
There are only two methods to implement.
|
|
The <span class="new_code">test()</span> method should
|
|
evaluate to true if the expectation is to pass, and
|
|
false otherwise.
|
|
The <span class="new_code">testMessage()</span> method
|
|
should simply return some helpful text explaining the test
|
|
that was carried out.
|
|
</p>
|
|
<p>
|
|
This class can now be used in place of the earlier expectation
|
|
classes.
|
|
</p>
|
|
<p>
|
|
Here is a more typical example, matching part of a hash...
|
|
<pre>
|
|
<strong>class JustField extends EqualExpectation {
|
|
private $key;
|
|
|
|
function __construct($key, $expected) {
|
|
parent::__construct($expected);
|
|
$this->key = $key;
|
|
}
|
|
|
|
function test($compare) {
|
|
if (! isset($compare[$this->key])) {
|
|
return false;
|
|
}
|
|
return parent::test($compare[$this->key]);
|
|
}
|
|
|
|
function testMessage($compare) {
|
|
if (! isset($compare[$this->key])) {
|
|
return 'Key [' . $this->key . '] does not exist';
|
|
}
|
|
return 'Key [' . $this->key . '] -> ' .
|
|
parent::testMessage($compare[$this->key]);
|
|
}
|
|
}</strong>
|
|
</pre>
|
|
We tend to seperate message clauses with
|
|
"&nbsp;->&nbsp;".
|
|
This allows derivative tools to reformat the output.
|
|
</p>
|
|
<p>
|
|
Suppose some authenticator is expecting to be given
|
|
a database row corresponding to the user, and we
|
|
only need to confirm the username is correct.
|
|
We can assert just their username with...
|
|
<pre>
|
|
$mock->expectOnce('authenticate',
|
|
array(new JustKey('username', 'marcus')));
|
|
</pre>
|
|
</p>
|
|
|
|
<h2>
|
|
<a class="target" name="unit"></a>Under the bonnet of the unit tester</h2>
|
|
<p>
|
|
The <a href="http://sourceforge.net/projects/simpletest/">SimpleTest unit testing framework</a>
|
|
also uses the expectation classes internally for the
|
|
<a href="unit_test_documentation.html">UnitTestCase class</a>.
|
|
We can also take advantage of these mechanisms to reuse our
|
|
homebrew expectation classes within the test suites directly.
|
|
</p>
|
|
<p>
|
|
The most crude way of doing this is to use the generic
|
|
<span class="new_code">SimpleTest::assert()</span> method to
|
|
test against it directly...
|
|
<pre>
|
|
<strong>class TestOfNetworking extends UnitTestCase {
|
|
...
|
|
function testGetValidIp() {
|
|
$server = &new Server();
|
|
$this->assert(
|
|
new ValidIp(),
|
|
$server->getIp(),
|
|
'Server IP address->%s');
|
|
}
|
|
}</strong>
|
|
</pre>
|
|
<span class="new_code">assert()</span> will test any expectation class directly.
|
|
</p>
|
|
<p>
|
|
This is a little untidy compared with our usual
|
|
<span class="new_code">assert...()</span> syntax.
|
|
</p>
|
|
<p>
|
|
For such a simple case we would normally create a
|
|
separate assertion method on our test case rather
|
|
than bother using the expectation class.
|
|
If we pretend that our expectation is a little more
|
|
complicated for a moment, so that we want to reuse it,
|
|
we get...
|
|
<pre>
|
|
class TestOfNetworking extends UnitTestCase {
|
|
...<strong>
|
|
function assertValidIp($ip, $message = '%s') {
|
|
$this->assert(new ValidIp(), $ip, $message);
|
|
}</strong>
|
|
|
|
function testGetValidIp() {
|
|
$server = &new Server();<strong>
|
|
$this->assertValidIp(
|
|
$server->getIp(),
|
|
'Server IP address->%s');</strong>
|
|
}
|
|
}
|
|
</pre>
|
|
It is rare to need the expectations for more than pattern
|
|
matching, but these facilities do allow testers to build
|
|
some sort of domain language for testing their application.
|
|
Also, complex expectation classes could make the tests
|
|
harder to read and debug.
|
|
In effect extending the test framework to create their own tool set.
|
|
</p>
|
|
|
|
</div>
|
|
References and related information...
|
|
<ul>
|
|
<li>
|
|
SimpleTest project page on <a href="http://sourceforge.net/projects/simpletest/">SourceForge</a>.
|
|
</li>
|
|
<li>
|
|
SimpleTest download page on <a href="http://www.lastcraft.com/simple_test.php">LastCraft</a>.
|
|
</li>
|
|
<li>
|
|
The expectations mimic the constraints in <a href="http://www.jmock.org/">JMock</a>.
|
|
</li>
|
|
<li>
|
|
<a href="http://simpletest.org/api/">Full API for SimpleTest</a>
|
|
from the PHPDoc.
|
|
</li>
|
|
</ul>
|
|
<div class="menu_back"><div class="menu">
|
|
<a href="index.html">SimpleTest</a>
|
|
|
|
|
<a href="overview.html">Overview</a>
|
|
|
|
|
<a href="unit_test_documentation.html">Unit tester</a>
|
|
|
|
|
<a href="group_test_documentation.html">Group tests</a>
|
|
|
|
|
<a href="mock_objects_documentation.html">Mock objects</a>
|
|
|
|
|
<a href="partial_mocks_documentation.html">Partial mocks</a>
|
|
|
|
|
<a href="reporter_documentation.html">Reporting</a>
|
|
|
|
|
<span class="chosen">Expectations</span>
|
|
|
|
|
<a href="web_tester_documentation.html">Web tester</a>
|
|
|
|
|
<a href="form_testing_documentation.html">Testing forms</a>
|
|
|
|
|
<a href="authentication_documentation.html">Authentication</a>
|
|
|
|
|
<a href="browser_documentation.html">Scriptable browser</a>
|
|
</div></div>
|
|
<div class="copyright">
|
|
Copyright<br>Marcus Baker 2006
|
|
</div>
|
|
</body>
|
|
</html>
|