Do you look for Code Coverage?

Last updated by Tom Bui [SSW] 4 months ago.See history

Code Coverage shows how much of your code is covered by tests and can be a useful tool for showing how effective your unit testing strategy is. However, it should be looked at with caution.

  • You should focus more on the quality and less on the quantity of tests
  • You should write tests for fragile code first and not waste time testing trivial methods
  • Remember the 80-20 rule - very high test coverage is a noble goal, but there are diminishing returns
  • If you're modifying code, write the test first, then change the code, then run the test to make sure it passes (aka red-green-refactor).
    Tip: This is made very easy by the "Live Unit Testing" feature in Visual Studio - see Do you use Live Unit Testing to see code coverage?
  • You should run your tests regularly (see Do you follow a Test Driven Process?) and, ideally, the tests will be part of your deployment pipeline

CodeCoverage2010
Figure: Code Coverage metrics in Visual Studio. This solution has high code coverage (around 80% on average)

Tip: To make sure your unit test coverage never decreases, make use of tools such as SonarQube and GitHub action checks to gate your deployment pipelines on non-decreasing test coverage.

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