Should it be “Arrange-Assert-Act-Assert”?

Question

Regarding the classic test pattern of Arrange-Act-Assert, I frequently find myself adding a counter-assertion that precedes Act. This way I know that the passing assertion

Answer 1

An Arrange-Assert-Act-Assert test can always be refactored into two tests:

1. Arrange-Assert

and

2. Arrange-Act-Assert

The first test will only assert on that which was set up in the Arrange phase, and the second test will only assert for that which happened in the Act phase.

This has the benefit of giving more precise feedback on whether it's the Arrange or the Act phase that failed, while in the original Arrange-Assert-Act-Assert these are conflated and you would have to dig deeper and examine exactly what assertion failed and why it failed in order to know if it was the Arrange or Act that failed.

It also satisfies the intention of unit testing better, as you are separating your test into smaller independent units.

Lastly, keep in mind that whenever you see similar Arrange sections in different test, you should try to pull these out into shared helper methods, so that your tests are more DRY and more maintainable in the future.