class MyClassTest extends PHPUnit_Framework_TestCase { public function testMyFunction() { $myObj = new MyClass(); $result = $myObj->myFunction(); $this->returnValue('expectedValue'); } }In this example, the `returnValue()` method is used to set the expected return value of the `myFunction()` method of the `MyClass` class to be `'expectedValue'`. This test case will fail if the actual return value of the `myFunction()` method does not match the expected value. The `PHPUnit_Framework_TestCase` class is a part of the PHPUnit library which is a testing framework for PHP. It provides tools for testing PHP applications and helps developers to write test cases in an organized and efficient way.