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Cover image for Code Smell 76 - Generic Assertions
Maxi Contieri
Maxi Contieri

Posted on • Originally published at

Code Smell 76 - Generic Assertions

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.


  • False Negatives

  • Lack of Trust


  1. Check the right case

  2. Assert for a functional case.

  3. Don't test implementation.

Sample Code


square = Square(5)

assert square.area() != 0

# This will lead to false negatives since it is too vague
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square = Square(5)

assert square.area() = 25

# Assertion should be precise
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With Mutation Testing techniques we can find these errors on our tests.


  • Testing


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


More info


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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