gistfile1.txt

# services.yml
app.some_service:
    class: SomeService
    calls:
       - [setSomeOtherService, ['@app.someOtherService']

# Test
function doSomethingWithOtherService() 
{
    $mockedOtherService = $this->prophesize(SomeOtherService::class);
    $mockedOtherService->find(Argument::Type(SomeType::class))->willReturn('something');
    $mockedOtherService = $mockedOtherService->reveal();

    $someService = new SomeService();
    $someService->setSomeOtherService($mockedOtherService);
    
    $return = $someService->doSomething();
    $this->assertEquals('Test', $return);
}

# services.yml
app.some_service:
    class: SomeService
    arguments:
       - '@app.someOtherService'

private $someService;
private $mockedOtherService;

function setUp()
{
    $this->mockedOtherService = $this->prophesize(SomeOtherService::class);
    $this->someService = new SomeService($this->mockedOtherService->reveal());
}

function doSomethingWithOtherService() 
{
    $this->mockedOtherService->find(Argument::Type(SomeType::class))->willReturn('something');
    
    $return = $someService->doSomething();

    $this->assertEquals('Test', $return);
}