Simpletest handbook does not cover unit testing

adding tags

As I don't have access to edit the http://drupal.org/simpletest-tutorial-drupal7 directly pasting unit test instructions here.

Writing unit tests requires a bit different approach than functional testing. Steps involved in writing an unit test:
<ul>
 <li>Creating the structure (class needs to inherit from DrupalUnitTestCase)</li>
 <li>Any required files need to be included manually in setUp function, enabling modules will not work as we are not accessing database in unit tests</li>
 <li>Create actual tests with the test case</li>
</ul>

To start, we need to create a class that extends DrupalUnitTestCase.

<?php
class UnittestExampleTestCase extends DrupalUnitTestCase {
}
?>

To make our test case available in the interface, we need to implement getInfo() same as with DrupalWebTestCase.

<?php
  public static function getInfo() {
    return array(
      'name' => 'Unittest Example',
      'description' => 'Ensure that the example_function works correctly.',
      'group' => 'Examples',
    );
  }
?>

As unit testing does not use database we need to manually include any required files.

<?php
  function setUp() {
    require_once DRUPAL_ROOT . '/modules/example/example.inc';
    parent::setUp();
  }
?> 

Now we need to create a test that will exercise the unit of code we are testing. For unit testing to be possible code that we are testing needs to always return same value for same parameters passed in. If code other than the code we are testing affects the return we cannot reliably test it.

<?php
  public function testExampleFunction() {
    $expected_result = 'example return';
    $input = 'example input',
    $result = example_function($input);
    $this->assertEqual($result, $expected_result, $expected_result, t('Example function returned expected result.));
  }
?>

Revised. Also created an issue to add code to example module #1261014: Add unit test example to simpletest example module.

Writing unit tests requires a bit different approach than functional testing. Steps involved in writing an unit test:
<ul>
  <li>Creating the structure (class needs to inherit from DrupalUnitTestCase)</li>
  <li>Any required files need to be included manually in setUp function, enabling modules will not work as we are not accessing database in unit tests</li>
  <li>Create actual tests with the test case</li>
</ul>

To start, we need to create a class that extends DrupalUnitTestCase.

<?php
class UnittestExampleTestCase extends DrupalUnitTestCase {

}
?>

To make our test case available in the interface, we need to implement getInfo() same as with DrupalWebTestCase.

<?php
  public static function getInfo() {
    return array(
      'name' => 'Simpletest unit test Example',
      'description' => 'Ensure that the simpletest_example_function works correctly.',
      'group' => 'Examples',
    );
  }
?>

As unit testing does not use database we need to manually include any required files.

<?php
  function setUp() {
    drupal_load('module', 'simpletest_example');
    parent::setUp();
  }
?> 

Now we need to create a test that will exercise the unit of code we are testing. For unit testing to be possible code that we are testing needs to always return same value for same parameters passed in. If code other than the code we are testing affects the return we cannot reliably test it.

<?php
  public function testSimpletestUnitTestExampleFunction() {
    $expected_result = 'example return';
    $input = 'example input';
    $result = simpletest_example_function($input);
    $this->assertEqual($result, $expected_result, t('Example function returned expected result.'));
  }
?>

Now you only need to come up with the most impossible input for your code and hope that it returns what you expect it to. Assertion functions available for unit tests are listed in http://api.drupal.org/api/drupal/modules--simpletest--drupal_web_test_case.php/class/DrupalUnitTestCase/7 and there are good examples of unit tests in core simpletest module.

I should read through all the docs first http://drupal.org/node/811254 holds unit test docs. IMO we should move it to the same level as SimpleTest Tutorial (Drupal 7) and merge the example into example module.

You're a star! Do you need a technical review? I can always tweet a link out and see if anyone will look at it, otherwise issues tend to stagnate...

I will review the existing unit test docs and provide example code for it in example module docs above will not be used.

Docs are updated at http://drupal.org/node/811254 example module code got committed in #1261014: Add unit test example to simpletest example module I think this one is done.