Research
Mutation testing AI-generated tests: 100% coverage, up to 22% of bugs missed
Claude Code's suites covered every line. Mutation testing showed which ones would notice a bug.
Blog
Notes on coverage and testing with coding agents.
Research
Claude Code security review skills, tested on 147 known vulnerabilities
Three popular skills, the built-in /security-review and Supercov with Jev, compared on accuracy, time and cost.
Engineering
Assertion coverage without mutation testing
Your tests pass. The total is wrong. Here's the missing assertion—and what coverage reports can't tell you.
Guide
Claude Code testing: unit tests, browser tests, and MCP
Write and run tests, check your app in a browser with MCP, and review what those tests actually prove.
Engineering
MC/DC coverage for JavaScript
Line and branch coverage can reach 100% while a condition goes untested. MC/DC shows what’s missing.