Assert::fail() is called with arguments only when they should be logged
typos
Assert::exception and error() generates much better error messages [Closes #22]
Assert: changed error messages according to the pattern "{actual} should be {expected}"

The intention is to have messages
- consistent for all assertions
- as short as possible
- and must be clear what is actual and what is expected value

PHPUnit's style "Failed asserting that 2301 is identical to '2301'." is rather long and makes you think what is actual and what expected value.
What about "Expected 2301 to be '2301'"? This is short with clear difference between actual and expected, but only when you read whole message, because word "Expected" is placed next to actual value.
And what about "Expected '2301' but got 2301"? It is great! But it is hard to create some others messages using this pattern. I.e. for assertContains.