Use a callback for return values with a mock in PHPUnit

test.php

<?php
class SomeClass { public function someMethod() {} }

class SomeClassTest extends PHPUnit_Framework_TestCase {
    public function testSomeMethod() {
        $someValue = ' ... ';
        
        $mock = $this->createMock('SomeClass');
        $mock
            ->expects($this->once())
            ->method('someMethod')
            ->will($this->returnCallback(function($arg1, $arg2) use ($someValue) {
                // ...
            }));

        $mock->someMethod('foo', 'bar');
    }
}