Mock a method within a model method in CakePHP - php

Question

I am running CakePHP 2.8.X, and am trying to write a unit test for a Model function.
Let's call the model Item, and I'm trying to test its getStatus method.
However, that model makes a call to its find within the getStatus method.
So something like this:
class Item extends Model
{
public function getStatus($id) {
// Calls our `$this->Item-find` method
$item = $this->find('first', [
'fields' => ['status'],
'conditions' => ['Item.id' => $id]
]);
$status = $item['status'];
$new_status = null;
// Some logic below sets `$new_status` based on `$status`
// ...
return $new_status;
}
}
The logic to set "$new_status" is a bit complex, which is why I want to write some tests for it.
However, I'm not entirely sure how to override the find call within Item::getStatus.
Normally when I want to mock a Model's function, I use $this->getMock coupled with method('find')->will($this->returnValue($val_here)), but I don't want to completely mock my Item since I want to test its actual getStatus function.
That is, in my test function, I'm going to be calling:
// This doesn't work since `$this->Item->getStatus` calls out to
// `$this->Item->find`, which my test suite doesn't know how to compute.
$returned_status = $this->Item->getStatus($id);
$this->assertEquals($expected_status, $returned_status);
So how do I communicate to my real Item model within my test that it should override its internal call to its find method?

Answer 1

I knew this had to be an issue others have faced, and it turns out PHPUnit has a very easy way to address this!
This tutorial essentially gave me the answer.
I do need to create a mock, but by only passing in 'find' as the methods I'd like to mock, PHPUnit helpfully leaves all other methods in my Model alone and does not override them.
The relevant part from the above tutorial is:
Passing an array of method names to your getMock second argument produces a mock object where the methods you have identified
Are all stubs,
All return null by default,
Are easily overridable
Whereas methods you did not identify
Are all mocks,
Run the actual code contained within the method when called (emphasis mine),
Do not allow you to override the return value
Meaning, I can take that mocked model, and call my getStatus method directly from it. That method will run its real code, and when it gets to find(), it'll just return whatever I passed into $this->returnValue.
I use a dataProvider to pass in what I want the find method to return, as well as the result to test against in my assertEquals call.
So my test function looks something like:
/**
* #dataProvider provideGetItemStatus
*/
public function testGetItemStatus($item, $status_to_test) {
// Only mock the `find` method, leave all other methods as is
$item_model = $this->getMock('Item', ['find']);
// Override our `find` method (should only be called once)
$item_model
->expects($this->once())
->method('find')
->will($this->returnValue($item));
// Call `getStatus` from our mocked model.
//
// The key part here is I am only mocking the `find` method,
// so when I call `$item_model->getStatus` it is actually
// going to run the real `getStatus` code. The only method
// that will return an overridden value is `find`.
//
// NOTE: the param for `getStatus` doesn't matter since I only use it in my `find` call, which I'm overriding
$result = $item_model->getStatus('dummy_id');
$this->assertEquals($status_to_test, $result);
}
public function provideGetItemStatus() {
return [
[
// $item
['Item' => ['id' = 1, 'status' => 1, /* etc. */]],
// status_to_test
1
],
// etc...
];
}

Answer 2

one way to mock find could be to use a test specific subclass.
You could create a TestItem that extends item and overrides find so it doesn't perform a db call.
Another way could be to encapsulate the new_status logic and unittests it independent of the model