Code Smell 91 — Test Asserts without Description

We are big fans of xUnit. But we don’t care much for the programmers.

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TL;DR: Use asserts with declarative descriptions.

Problems

• Readability
• Hard debugging
• Time waste

Solutions

1. Put a nice descriptive assertion
2. Share guides for problem-solving

Sample Code

Wrong

<?
public function testNoNewStarsAppeared(): void
  {
     $expectedStars = $this->historicStarsOnFrame();
     $observedStars = $this->starsFromObservation();
     //These sentences get a very large collection
     $this->assertEquals($expectedStars, $observedStars);
     //If something fails we will have a very hard debugging time
    }

Right

<?
public function testNoNewStarsAppeared(): void
  {
     $expectedStars = $this->historicStarsOnFrame();
     $observedStars = $this->starsFromObservation();
     //These sentences get a very large collection
     $newStars = array_diff($expectedStars, $observedStars);
     $this->assertEquals($expectedStars, $observedStars ,
         'There are new stars ' . print_r($newStars,true));
     //Now we can see EXACTLY why the assertion failed with a clear and
     //Declarative Message 
    }

Detection

Since assert and assertDescription are different functions, we can adjust our policies to favour the latter.

Tags

• Test Smells

Conclusion

Be respectful to the reader of your assertions.

It might even be yourself!

More Info

• XUnit: Assert Description Deprecation

Always code as if the guy who ends up maintaining your code will be a violent psychopath who knows where you live.

John Woods

Software Engineering Great Quotes

This article is part of the CodeSmell Series.

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