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Run this workflow to measure test coverage, mutation score, and test strength across your project. The report breaks down metrics per module and per class.

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Prerequisites

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Project requirements

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Run the workflow

The workflow:
  1. Detects your build system, language, and modules
  2. Configures coverage and mutation testing tools if not already present
  3. Runs coverage and mutation analysis
  4. Displays a per-module quality report

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Filter by module

Limit the assessment to specific modules with --module:

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Filter by package or class

Scope the assessment to a specific package or class with --filter:

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Understanding the report

The report shows four metrics for each module and class:

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What the metrics tell you

  • High line coverage, low mutation score: Your tests run the code but don’t verify its behavior. Assertions may be missing or too weak.
  • Low line coverage, high test strength: The code that is covered is tested effectively, but not enough code is actually covered.
  • Low line coverage: Parts of your code aren’t reached by any test.

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Tool configuration

The workflow automatically configures mutation testing tools if they are not already present:
  • Java: Adds the PIT (Pitest) Maven or Gradle plugin
  • Python: Installs mutmut in the virtual environment
Tool configuration changes are committed to your repository only after a successful run. On subsequent runs, the tools are already configured and the workflow skips this step.

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Next steps

Address gaps identified in the report by running the Diffblue Testing Agent: