Mock Objects in PHPUnit to emulate Static Method Calls?

Question

I am trying to test a class that manages data access in the database (you know, CRUD, essentially). The DB library we're using happens to have an API wherein you first get the table object by a static call:

function getFoo($id) {
  $MyTableRepresentation = DB_DataObject::factory("mytable");
  $MyTableRepresentation->get($id);
  ... do some stuff
  return $somedata
}

...you get the idea.

We're trying to test this method, but mocking the DataObject stuff so that (a) we don't need an actual db connection for the test, and (b) we don't even need to include the DB_DataObject lib for the test.

However, in PHPUnit I can't seem to get $this->getMock() to appropriately set up a static call. I have...

        $DB_DataObject = $this->getMock('DB_DataObject', array('factory'));

...but the test still says unknown method "factory". I know it's creating the object, because before it said it couldn't find DB_DataObject. Now it can. But, no method?

What I really want to do is to have two mock objects, one for the table object returned as well. So, not only do I need to specify that factory is a static call, but also that it returns some specified other mock object that I've already set up.

I should mention as a caveat that I did this in SimpleTest a while ago (can't find the code) and it worked fine.

What gives?

[UPDATE]

I am starting to grasp that it has something to do with expects()

Answer 1

I agree with both of you that it would be better not to use a static call. However, I guess I forgot to mention that DB_DataObject is a third party library, and the static call is their best practice for their code usage, not ours. There are other ways to use their objects that involve constructing the returned object directly. It just leaves those darned include/require statements in whatever class file is using that DB_DO class. That sucks because the tests will break (or just not be isolated) if you're meanwhile trying to mock a class of the same name in your test--at least I think.

Answer 2

When you cannot alter the library, alter your access of it. Refactor all calls to DB_DataObject::factory() to an instance method in your code:

function getFoo($id) {
  $MyTableRepresentation = $this->getTable("mytable");
  $MyTableRepresentation->get($id);
  ... do some stuff
  return $somedata
}

function getTable($table) {
  return DB_DataObject::factory($table);
}

Now you can use a partial mock of the class you're testing and have getTable() return a mock table object.

function testMyTable() {
  $dao = $this->getMock('MyTableDao', array('getMock'));
  $table = $this->getMock('DB_DataObject', ...);
  $dao->expects($this->any())
      ->method('getTable')
      ->with('mytable')
      ->will($this->returnValue($table));
  $table->expects...
  ...test...
}

Answer 3

This is a good example of a dependency in your code - the design has made it impossible to inject in a Mock rather than the real class.

My first suggestion would be to try and refactor the code to use an instance rather than a static call.

Answer 4

What's missing (or not?) from your DB_DataObject class is a setter to pass a prepared db object before calling the factory method. That way you can pass a mock or a custom db object (with the same interface) should the need arise.

In your test setup:

 public function setUp() {
      $mockDb = new MockDb();
      DB_DataObject::setAdapter($mockDb);
 }

The factory() method should return the mocked DB instance. If it's not already integrated into your class, you will probably have to refactor the factory() method as well to make it work.

Answer 5

Are you require/including the class file for DB_DataObject in your test case? If the class doesn't exist before PHPUnit tries to mock the object you can get errors like this.

Answer 6

With PHPUnit MockFunction extension plus runkit you can also mock static methods. Be careful, because it's monkey patching and therefore should only be used in extreme cases. Does not substitute good programming practices.

https://github.com/tcz/phpunit-mockfunction