gistfile1.php

<?php

//PHPUnit
public function testApply() {
    $mock = $this->getMock('My\Foo\Class', array('apply'));
    $mock->expects($this->any())
         ->method('apply')
         ->with('foo')
         ->will($this->returnValue('bar'));
    
    $target = new My\Bar\Class($mock);
    $this->assertEquals('bar', $target->apply('foo'));
}

//PhpSpec2/Prophecy
function let(\My\Foo\Class $foo) {
    $this->beConstructedWith($foo);
}

function it_applies_foo_modificator($foo) {
    $foo->apply('foo')->willReturn('bar');

    $this->apply('foo')->shouldReturn('bar');
}

You can do ->with('foo') in the PHPUnit example.

@whatthejeff you're right! Fixed.

<?php

// PHPUnit 4.0
public function testApply() {
    $mock = $this->getMock('My\Foo\Class', array('apply'));
    $mock->method('apply')->with('foo')->willReturn('bar');

    $target = new My\Bar\Class($mock);
    $this->assertEquals('bar', $target->apply('foo'));
}