Unit testing Anti-patterns catalogue

Question

anti-pattern : there must be at least two key elements present to formally distinguish an actual anti-pattern from a simple bad habit, bad practice, or bad idea:

• Some repeated pattern of action, process or structure that initially appears to be beneficial, but ultimately produces more bad consequences than beneficial results, and
• A refactored solution that is clearly documented, proven in actual practice and repeatable.

Vote for the TDD anti-pattern that you have seen "in the wild" one time too many.
The blog post by James Carr and Related discussion on testdrivendevelopment yahoogroup

If you've found an 'unnamed' one.. post 'em too. One post per anti-pattern please to make the votes count for something.

My vested interest is to find the top-n subset so that I can discuss 'em in a lunchbox meet in the near future.

Answer 1

The Forty Foot Pole Test

Afraid of getting too close to the class they are trying to test, these tests act at a distance, separated by countless layers of abstraction and thousands of lines of code from the logic they are checking. As such they are extremely brittle, and susceptible to all sorts of side-effects that happen on the epic journey to and from the class of interest.

Answer 2

The Inspector
A unit test that violates encapsulation in an effort to achieve 100% code coverage, but knows so much about what is going on in the object that any attempt to refactor will break the existing test and require any change to be reflected in the unit test.

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'how do I test my member variables without making them public... just for unit-testing?'

Answer 3

The Test With No Name -- Nick Pellow

The test that gets added to reproduce a specific bug in the bug tracker and whose author thinks does not warrant a name of its own. Instead of enhancing an existing, lacking test, a new test is created called testForBUG123.

Two years later, when that test fails, you may need to first try and find BUG-123 in your bug tracker to figure out the test's intent.

Answer 4

The Sleeper, aka Mount Vesuvius -- Nick Pellow

A test that is destined to FAIL at some specific time and date in the future. This often is caused by incorrect bounds checking when testing code which uses a Date or Calendar object. Sometimes, the test may fail if run at a very specific time of day, such as midnight.

'The Sleeper' is not to be confused with the 'Wait And See' anti-pattern.

That code will have been replaced long before the year 2000 -- Many developers in 1960

Answer 5

Happy Path

The test stays on happy paths (i.e. expected results) without testing for boundaries and exceptions.

JUnit Antipatterns

Answer 6

Doppelgänger

In order to test something, you have to copy parts of the code under test into a new class with the same name and package and you have to use classpath magic or a custom classloader to make sure it is visible first (so your copy is picked up).

This pattern indicates an unhealthy amount of hidden dependencies which you can't control from a test.

I looked at his face ... my face! It was like a mirror but made my blood freeze.