Refactoring tests

[carusogabriel]

I've refactored some tests, using:

• PHPUnit assertion method instead of PHP's;
• assertSame instead of assertEquals, to strict compare what we need;
• swipe some arguments, to match PHPUnit assertion method correct arguments order.

Thanks to Rector find them.

[TomasVotruba]

Hey, thanks for the PR.

I wanted to finish big changes first, so now we can update the tests.

Could you rebase or rather re-send PR on current master? Whatever is simpler for you :+1:

Also removing @expectedException annotations would be great!

[carusogabriel]

Sure, I'll rebase and fix conflicts.