jasonmccreary/test-double

Test Double

Tired of remembering the difference between mocks, partials, and spies in Mockery? I am, which is why I created double() - a simple helper method to make using Mockery easier., _(*1)

When writing tests I don't want to think about the differences between fakes, mocks, and spies. I just to create a generic test double and focus on writing my test. This generalization is common in other testing frameworks such as RSpec, td.js, and more., _(*2)

Installation

To install the latest version of the double() helper, run the command:, _(*3)

composer require --dev jasonmccreary/test-double

Usage

Anytime you need to create a test double simply call double(), _(*4)

By default, double() returns an object that will allow you to stub methods as well as verify method calls., _(*5)

<?php
$td = double();

$td->shouldReceive('someMethod')->andReturn(5);

$td->someMethod();       // returns 5
$td->unstubbedMethod();  // returns null, does not throw an exception

$td->anotherMethod();
$td->shouldHaveReceived('anotherMethod');

In Mockery, this test double is equivalent to Mockery::mock()->shouldIgnoreMissing() or, in recent versions, Mockery::spy()., _(*6)

You can also pass double() a reference to a class or interface. This will create a test object that extends the class or implements the interface. This allows the double to pass any type hints or type checking in your implementation., _(*7)

<?php
$td = double(Str::class);

$td->shouldReceive('length')->andReturn(5);

$td->length();           // 5
$td->substr(1, 3);       // null

$td instanceof Str;      // true

$td->shouldHaveReceived('substr')->with(1, 3);

Finally, double() accepts a second argument of passthru. By default, passthru is false. When set to true, the test object will pass any method calls through to the underlying object., _(*8)

In Mockery, this is equivalent to Mockery::mock(Number::class)->shouldDeferMissing()., _(*9)

<?php
class Number
{
    public function one()
    {
        return 1;
    }

    public function random()
    {
        return 5;
    }
}

$td = double(Number::class, true);

$td->shouldReceive('random')->andReturn(21);

$td->random();            // 21
$td->one();               // 1

$td instanceof Number;    // true

$td->shouldHaveReceived('one');

Note: passthru can only be used when creating a test double with a class reference as that is the only time an underlying implementation exists., _(*10)

In the end, double() is an opinionated way to create test objects for your underlying code. If it does not meet your needs, you can always create a Mockery::mock() directly. However, doing so is likely a smell you're testing your implementation in a way that does not reflect real world behavior. Remember, double() returns an object which implements the MockeryInterface. So it can be treated as any other Mockery::mock() object., _(*11)