Cosmic Ray vs pytest-gremlins

Cosmic Ray

5.8 #6 in Mutation Testing Tools

About Cosmic Ray

pytest-gremlins

5.4 #13 in Mutation Testing Tools

About pytest-gremlins
Cosmic Raypytest-gremlins
Free planNoNo
Free trialNoNo
Paid from——
Open sourceNoNo
PlatformsLinux, self-hosted—
Free planYes—
Supported languagesPython 3Python
Test frameworksunittest, pytest, nosepytest
Incremental analysisYesYes
Parallel executionYesYes
Surviving mutant reportsYesYes
Mutation operatorsbinary operator replacement; boolean replacement; break/continue replacement; comparison operator replacement; exception replacement; keyword replacement; number replacement; decorator removal; unary operator replacement; zero-iteration for loopscomparison, boundary, boolean, arithmetic, return
Mutation quality gate—Yes

Both are listed in Best Mutation Testing Tools. On Samsung Mobile US Press, Cosmic Ray scores higher on our published basis.