Bar.php

<?php

class Bar
{
    public function doSth()
    {
        echo 'sth';
    }
}

Foo.php

<?php

class Foo
{
    /**
     * @param VO $vo
     */
    public function handle(VO $vo)
    {
        $vo->bar->doSth();
    }
}

FooSpec.php

<?php

class FooSpec extends ObjectBehavior
{
    function it_should_call_do_sth(Bar $bar)
    {
        $vo = new VO();
        /* $bar is actually a \PhpSpec\Wrapper\Collaborator when running the spec */
        $vo->bar = $bar->getWrappedObject();
        $this->handle($vo);
        $bar->doSth()->shouldHaveBeenCalled();
    }
}

output

Test fails with:
 - it should call do sth
      no calls have been made that match:
        Double\Bar\P90->doSth()
      but expected at least one.
       0 vendor/phpspec/prophecy/src/Prophecy/Prediction/CallPrediction.php:76
         throw new Prophecy\Exception\Prediction\NoCallsException("No calls have been made t...")
       1 vendor/phpspec/prophecy/src/Prophecy/Prophecy/MethodProphecy.php:295
         Prophecy\Prediction\CallPrediction->check([array:0], [obj:Prophecy\Prophecy\ObjectProphecy], [obj:Prophecy\Prophecy\MethodProphecy])
       2 vendor/phpspec/prophecy/src/Prophecy/Prophecy/MethodProphecy.php:315
         Prophecy\Prophecy\MethodProphecy->shouldHave([obj:Prophecy\Prediction\CallPrediction])
       3 spec/FooSpec.php:24
         Prophecy\Prophecy\MethodProphecy->shouldHaveBeenCalled()
       4 [internal]
         spec\FooSpec->it_should_call_do_sth([obj:PhpSpec\Wrapper\Collaborator])
       5 vendor/phpspec/phpspec/src/PhpSpec/Runner/ExampleRunner.php:143
         ReflectionMethod->invokeArgs([obj:spec\FooSpec], [array:1])
       6 vendor/symfony/symfony/src/Symfony/Component/Console/Application.php:831
         Symfony\Component\Console\Command\Command->run([obj:Symfony\Component\Console\Input\ArgvInput], [obj:Symfony\Component\Console\Output\ConsoleOutput])
       7 vendor/symfony/symfony/src/Symfony/Component/Console/Application.php:186
         Symfony\Component\Console\Application->doRunCommand([obj:PhpSpec\Console\Command\RunCommand], [obj:Symfony\Component\Console\Input\ArgvInput], [obj:Symfony\Component\Console\Output\ConsoleOutput])
       8 vendor/phpspec/phpspec/src/PhpSpec/Console/Application.php:97
         Symfony\Component\Console\Application->doRun([obj:Symfony\Component\Console\Input\ArgvInput], [obj:Symfony\Component\Console\Output\ConsoleOutput])
       9 vendor/phpspec/phpspec/bin/phpspec:26
         Symfony\Component\Console\Application->run()

VO.php

<?php

class VO
{
    /** @var Bar */
    public $bar;
}