CakePHP3: Mock methods in integration tests? - testing

Question

I'm new to unit / integration testing and I want to do an integration test of my controller which looks simplified like this:
// ItemsController.php
public function edit() {
// some edited item
$itemEntity
// some keywords
$keywordEntities = [keyword1, keyword2, ...]
// save item entity
if (!$this->Items->save($itemEntity)) {
// do some error handling
}
// add/replace item's keywords
if (!$this->Items->Keywords->replaceLinks($itemEntity, $keywordEntities)) {
// do some error handling
}
}
I have the models Items and Keywords where Items belongsToMany Keywords. I want to test the error handling parts of the controller. So I have to mock the save() and replaceLinks() methods that they will return false.
My integration test looks like this:
// ItemsControllerTest.php
public function testEdit() {
// mock save method
$model = $this->getMockForModel('Items', ['save']);
$model->expects($this->any())->method('save')->will($this->returnValue(false));
// call the edit method of the controller and do some assertions...
}
This is working fine for the save() method. But it is not working for the replaceLinks() method. Obviously because it is not part of the model.
I've also tried something like this:
$method = $this->getMockBuilder(BelongsToMany::class)
->setConstructorArgs([
'Keywords', [
'foreignKey' => 'item_id',
'targetForeignKey' => 'keyword_id',
'joinTable' => 'items_keywords'
]
])
->setMethods(['replaceLinks'])
->getMock();
$method->expects($this->any())->method('replaceLinks')->will($this->returnValue(false));
But this is also not working. Any hints for mocking the replaceLinks() method?

Answer 1

When doing controller tests, I usually try to mock as less as possible, personally if I want to test error handling in controllers, I try to trigger actual errors, for example by providing data that fails application/validation rules. If that is a viable option, then you might want to give it a try.
That being said, mocking the association's method should work the way as shown in your example, but you'd also need to replace the actual association object with your mock, because unlike models, associations do not have a global registry in which the mocks could be placed (that's what getMockForModel() will do for you) so that your application code would use them without further intervention.
Something like this should do it:
$KeywordsAssociationMock = $this
->getMockBuilder(BelongsToMany::class) /* ... */;
$associations = $this
->getTableLocator()
->get('Items')
->associations();
$associations->add('Keywords', $KeywordsAssociationMock);
This would modify the Items table object in the table registry, and replace (the association collection's add() acts more like a setter, ie it overwrites) its actual Keywords association with the mocked one. If you'd use that together with mocking Items, then you must ensure that the Items mock is created in beforehand, as otherwise the table retrieved in the above example would not be the mocked one!