silverstripe-framework/tests/testing/YamlFixtureTest.php

<?php

class YamlFixtureTest extends SapphireTest {
	static $fixture_file = 'sapphire/tests/testing/YamlFixtureTest.yml';

	protected $extraDataObjects = array(
		'YamlFixtureTest_DataObject',
		'YamlFixtureTest_DataObjectRelation',
	);
	
	function testSQLInsert() {
		$object1 = DataObject::get_by_id("YamlFixtureTest_DataObject", $this->idFromFixture("YamlFixtureTest_DataObject", "testobject1"));
		$this->assertTrue($object1->ManyMany()->Count() == 2, "Should be 2 items in this manymany relationship");
		$object2 = DataObject::get_by_id("YamlFixtureTest_DataObject", $this->idFromFixture("YamlFixtureTest_DataObject", "testobject2"));
		$this->assertTrue($object2->ManyMany()->Count() == 2, "Should be 2 items in this manymany relationship");
	}
}

class YamlFixtureTest_DataObject extends DataObject implements TestOnly {
	static $db = array(
		"Name" => "Varchar"
	);
	static $many_many = array(
		"ManyMany" => "YamlFixtureTest_DataObjectRelation"
	);
}

class YamlFixtureTest_DataObjectRelation extends DataObject implements TestOnly {
	static $db = array(
		"Name" => "Varchar"
	);
	static $belongs_many_many = array(
		"TestParent" => "YamlFixtureTest_DataObject"
	); 
}