Question 1

How does Infection compare to PHPUnit code coverage?

Accepted Answer

Infection assesses test quality by injecting faults to see if tests catch them, providing a deeper metric than PHPUnit's line coverage, which only shows executed code. It highlights weak spots that coverage misses.

Question 2

How to set up Infection in a CI/CD pipeline?

Accepted Answer

Install Infection via Composer and add it as a step in your CI configuration; the README links to documentation with examples for GitHub Actions and other systems, focusing on parallel runs to manage performance.

Question 3

What's a good mutation score to aim for with Infection?

Accepted Answer

Aim for a Mutation Score Indicator (MSI) above 80% for critical code, but it varies by project risk. Infection's reports help prioritize improvements based on mutation survival rates.

Question 4

Infection vs Humbug: which is better for PHP mutation testing?

Accepted Answer

Infection is the active successor to Humbug, which is discontinued. Infection offers better performance, more features, and ongoing support, making it the recommended choice for new projects.

Question 5

How to create custom mutators in Infection?

Accepted Answer

Extend Infection's mutator classes and implement your mutation logic; the documentation provides guidelines for registering custom mutators to target specific code patterns.

Question 6

Does Infection work with Laravel or Symfony projects?

Accepted Answer

Yes, Infection is compatible with Laravel and Symfony as it integrates with PHPUnit, commonly used in these frameworks. You may need to adjust configuration for framework-specific structures.

Question 7

How can I speed up Infection runs on large codebases?

Accepted Answer

Use Infection's parallel processing, enable caching, and limit mutations to changed files or critical modules. The README mentions optimizations, but resource scaling might still be needed.

Infection

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