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chromium/external/github.com/WebKit/webkit/refs/heads/main/./JSTests
tree: e527575a801a118f803c39bb4d7185bbfc567d06
  1. ChakraCore/
  2. complex/
  3. controlFlowProfiler/
  4. es6/
  5. exceptionFuzz/
  6. executableAllocationFuzz/
  7. heapProfiler/
  8. microbenchmarks/
  9. modules/
  10. mozilla/
  11. perf/
  12. regexp/
  13. slowMicrobenchmarks/
  14. stress/
  15. test262/
  16. typeProfiler/
  17. wasm/
  18. .gitattributes
  19. AGENTS.md
  20. ChakraCore.yaml
  21. CLAUDE.md
  22. complex.yaml
  23. controlFlowProfiler.yaml
  24. es6.yaml
  25. exceptionFuzz.yaml
  26. executableAllocationFuzz.yaml
  27. ftl-materialize-regexp-string-iterator.js
  28. heapProfiler.yaml
  29. microbenchmarks.yaml
  30. modules.yaml
  31. README.md
  32. typeProfiler.yaml
  33. wasm.yaml
JSTests/README.md

JSTests

Running Tests

Tests are not always set up to run directly. Instead run them through Tools/Scripts/run-javascriptcore-tests, which runs everything, or Tools/Scripts/run-jsc-stress-tests <collection>, which runs a specific subset. For day-to-day development, the JSTests/stress and JSTests/wasm.yaml collections are sufficient for catching most bugs.

Tests are run in a variety of different JSC configurations, for example with various JIT tiers disabled, concurrent compilation off, or the GC running continuously. These configurations show up as a suffix on the test name. For example, stress/array-push.js.ftl-eager-no-cjit corresponds to JSTests/stress/array-push.js with tier-up thresholds lowered and concurrent JIT off.

run-jsc-stress-tests looks for a jsc in the release build directory unless --debug or --jsc <path> is passed. run-javascriptcore-tests builds one first unless --no-build or --root <path> is passed.

run-jsc-stress-tests takes a collection (a directory or a .yaml file), not a single test file. To run a limited subset, pass --filter <regex>, which will pattern match on the test's name/configuration. e.g. run-jsc-stress-tests JSTests/stress --filter array-push.

Adding Tests

Put tests that only target JS behavior in JSTests/stress and tests that involve wasm in JSTests/wasm/stress.

New tests are required to adhere to the following rules:

  1. Tests must run in under 200ms in all configurations. This can be checked by passing --report-execution-time to run-jsc-stress-tests.
  2. Use testLoopCount or wasmTestLoopCount to control how many iterations a test runs. The jsc CLI sets these based on the configuration of the test, so tests iterate enough to tier up where that matters and exit early where it doesn't.
  3. Tests fail by crashing or throwing an uncaught exception, so assertions must throw rather than print. Add //@ mustCrash! or //@ requireOptions("--exception=<exception-name>") to the top of the test file if testing expected crashes/exceptions, respectively.
  4. Don't print or log unless a test is about to fail. Test output goes straight to the terminal, so extra logging is noisy and disruptive.
  5. Make sure the test actually reproduces the bug. Run the test against a build without the fix and make sure it fails.