silverstripe-framework/docs/en/topics/testing/create-silverstripe-test.md

How To Create a SilverStripe Test

A unit test class will test the behaviour of one of your [api:DataObjects]. This simple fragment of [api:SiteTreeTest] provides us the basics of creating unit tests.

:::php
<?php
class SiteTreeTest extends SapphireTest {
	
	// Define the fixture file to use for this test class
	private static $fixture_file = 'SiteTreeTest.yml';

	/**	
	 * Test generation of the URLSegment values.
	 *  - Turns things into lowercase-hyphen-format
	 *  - Generates from Title by default, unless URLSegment is explicitly set
	 *  - Resolves duplicates by appending a number
	 */
	public function testURLGeneration() {
		$expectedURLs = array(
			'home' => 'home',
			'staff' => 'my-staff',
			'about' => 'about-us',
			'staffduplicate' => 'my-staff-2',
			'product1' => '1-1-test-product',
			'product2' => 'another-product',
			'product3' => 'another-product-2',
			'product4' => 'another-product-3',
		);
		
		foreach($expectedURLs as $fixture => $urlSegment) {
			$obj = $this->objFromFixture('Page', $fixture);
			$this->assertEquals($urlSegment, $obj->URLSegment);
		}
	}
}

There are a number of points to note in this code fragment:

• Your test is a subclass of SapphireTest. Both unit tests and functional tests are a subclass of [api:SapphireTest].
• static $fixture_file is defined. The testing framework will automatically set up a new database for each of your tests. The initial database content will be sourced from the YML file that you list in $fixture_file. The property can take an array of fixture paths.
• Each method that starts with the word "test" will be executed by the TestRunner. Define as many as you like; the database will be rebuilt for each of these.
• $this->objFromFixture($className, $identifier) can be used to select one of the objects named in your fixture file. To identify to the object, we provide a class name and an identifier. The identifier is specified in the YML file but not saved in the database anywhere. objFromFixture() looks the [api:DataObject] up in memory rather than using the database. This means that you can use it to test the functions responsible for looking up content in the database.

Assertion commands

$this->assertEquals() is an example of an assertion function.
These functions form the basis of our tests - a test fails if and only if one or more of the assertions fail.
See the PHPUnit manual for a listing of all PHPUnit's built-in assertions.

The [api:SapphireTest] class comes with additional assertions which are more specific to the framework, e.g. [assertEmailSent](api:SapphireTest->assertEmailSent()) which can simulate sending emails through the Email->send() API without actually using a mail server (see the testing emails) guide.

Fixtures

Often you need to test your functionality with some existing data, so called "fixtures". These records are inserted on a fresh test database automatically. Read more about fixtures.