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Code Smell 76 - Generic Assertions

Maxi Contieri
Learn something new every day. - I am a senior software engineer working in industry, teaching and writing on software design, SOLID principles, DDD and TDD.
Originally published at maximilianocontieri.com ・2 min read

Don't make weak tests to create a false sensation of coverage.

TL;DR: Test Assertions should be precise. Not too Vague and not too specific. There is no silver bullet.

Problems

  • False Negatives

  • Lack of Trust

Solutions

  1. Check the right case

  2. Assert for a functional case.

  3. Don't test implementation.

Sample Code

Wrong

square = Square(5)

assert square.area() != 0

# This will lead to false negatives since it is too vague
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Right

square = Square(5)

assert square.area() = 25

# Assertion should be precise
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Detection

With Mutation Testing techniques we can find these errors on our tests.

Tags

  • Testing

Conclusion

We should use development techniques like TDD that request concrete business cases and make concrete assertions based on our domain.

Relations

More info

Credits

This smell was inspired by Mario Cervera and used with his permission.

Photo by Fleur on Unsplash


A program that produces incorrect results twice as fast is infinitely slower.

John Osterhout


This article is part of the CodeSmell Series.

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