<?php
class ClassWithProtectedMethod
{
    public function foo()
    {
        return $this->bar();
    }

    protected function bar()
    {
        return 'bar';
    }
}

class ProtectedStubTest extends PHPUnit_Framework_TestCase
{
    public function testProtectedStub()
    {
        $stub = $this->getMock('ClassWithProtectedMethod', array('bar'));

        $stub->expects($this->any())
             ->method('bar')
             ->will($this->returnValue('stub'));

        $this->assertEquals('stub', $stub->foo());
    }
}
?>

sb@vmware ~ % phpunit ProtectedStubTest
PHPUnit 3.5.2 by Sebastian Bergmann.

.

Time: 0 seconds, Memory: 7.00Mb

OK (1 test, 2 assertions)