Say it like this
- Let's run mutation testing to validate our test coverage
- The mutation testing results show gaps in our test suite
- We should improve our mutation score before shipping to production
Use it at work
Testing
- Mutation testing shows our tests miss a lot of bugs.
- Let's run mutation testing on the billing module.
Explaining
- Mutation testing changes the code to see if tests fail.
- High coverage doesn't mean good tests. Mutation testing proves it.
Planning
- Mutation testing is slow, so let's run it nightly.
- What's our mutation score?
Don't say this
Mutation testing does not fix bugs; it reveals whether tests are strong enough to catch bugs if they existed.
Practice
Try it
4 quick exercises
1. We need to _______ our test suite to ensure it catches real bugs before production.
2. Which sentence uses mutation testing correctly?
3. How would a QA lead naturally express concern about test quality?
4. Rewrite this in natural tech English using mutation testing: 'We need to check if our tests are good enough by seeing if they catch small code changes.'
Say it out loud
Phrase 1 of 3
"Let's run mutation testing to validate our test coverage"
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More about mutation testing
Real examples(3)
- in a standup
"I ran mutation testing on the payment module yesterday and found that our tests were not catching edge cases with decimal values."
- in a code review
"This test looks good, but let's add mutation testing to ensure we're actually validating the business logic and not just happy paths."
- in a team meeting
"Our mutation testing score improved from 65 percent to 82 percent after we added those extra assertions to the authentication tests."
More mistakes(2)
Handle with care. Often confused with regular unit testing. Mutation testing is a technique that deliberately breaks code to verify tests catch the bugs, not a way to test code for mutations or changes.
- ✕Mutation testing is the same as code coverage.✓Mutation testing measures test effectiveness; code coverage measures which lines are executed.
Code coverage only tells you if code runs; mutation testing tells you if tests verify correctness.
- ✕We need mutation testing on all our legacy code right now.✓We should apply mutation testing to critical modules first, then expand gradually.
Mutation testing is resource-intensive; prioritizing critical code is more practical.
Other forms(3)
- mutation testing noun
"Mutation testing revealed that our validation tests were too weak."
- mutation score noun
"Our mutation score of 85 percent indicates strong test quality."
- run mutation testing verb
"Let us run mutation testing on this new feature before we merge it."
Often used with(5)
- mutation testing score · Percentage indicating how many mutations were caught by tests
- run mutation testing · Execute a mutation testing analysis on your codebase
- mutation testing tool · Software like PIT, Stryker, or Mutmut that performs mutation testing
- mutation testing results · Output showing which mutations were caught and which escaped
- improve mutation score · Strengthen tests to catch more injected mutations
Similar words(2)
- test effectiveness analysis · Broader term; mutation testing is a specific technique within this category
- fault injection · Similar concept but can refer to injecting faults in infrastructure or systems, not just code
Opposites(2)
- unit testing
- code coverage
Questions(5)
- What does mutation testing mean in software engineering?
- Mutation testing is a technique that deliberately introduces small bugs into code to verify whether your test suite can detect them. It measures test effectiveness by injecting mutations like changing operators or return values, then checking if tests fail. If tests catch the mutations, your test suite is strong; if mutations survive, you have gaps in your testing.
- How do you use mutation testing in a sentence at work?
- You can say: 'Let us run mutation testing on the authentication module' or 'Our mutation testing score is 75 percent, which means we need stronger tests.' Use it as a noun phrase when discussing testing practices or results.
- Is mutation testing formal or informal?
- Mutation testing is formal technical language appropriate for code reviews, technical documentation, and professional discussions. It is not casual or slang, though it is commonly used in everyday tech conversations among developers and QA engineers.
- How is mutation testing different from code coverage?
- Code coverage measures the percentage of code lines executed by tests, while mutation testing measures whether tests actually verify correct behavior. You can have 100 percent code coverage but still have weak tests that do not catch bugs. Mutation testing is a more thorough quality metric.
- What tools are used for mutation testing?
- Popular mutation testing tools include PIT for Java, Stryker for JavaScript/TypeScript, Mutmut for Python, and Infection for PHP. Each tool injects mutations specific to the programming language and framework.
