testing

name	testing
description	Detect the project's test framework (pytest, jest, go test, cargo test, mocha, rspec) and run, parse, and triage failures.

Testing skill

When to use

• User asks to run tests, fix failing tests, or add tests
• User asks why tests are failing or to debug a test failure
• User asks to find the test framework used in a project

When NOT to use

• The user wants to write production code alongside tests — use coding skill
• The user is working with CI/CD pipeline config — use system-admin or coding skill

Procedure

1. Detect the test framework: check project root files (see detection cascade below).
2. Run tests from the project root.
3. Capture stderr as well as stdout — most frameworks print errors to stderr.
4. Parse the first failure deeply: read the failing test file and the code under test to understand why.
5. Fix root cause, not symptoms. Don't suppress assertions — fix the code or the test.
6. Re-run to confirm the fix.

Detection cascade

Signal	Framework	Command
pyproject.toml or pytest.ini or setup.cfg [tool:pytest]	pytest	pytest
package.json scripts with "jest"	Jest	npx jest
package.json scripts with "vitest"	Vitest	npx vitest run
package.json scripts with "mocha"	Mocha	npx mocha
go.mod	go test	go test ./...
Cargo.toml	cargo test	cargo test
Gemfile with rspec	RSpec	bundle exec rspec

When uncertain, run cat package.json | python3 -c "import json,sys; d=json.load(sys.stdin); print(d.get('scripts',{}))" to inspect scripts.

Recipes

Run pytest with verbose output on failures:

pytest -v --tb=short 2>&1

Run only failed tests:

pytest --lf

Run specific test by name:

pytest -k "test_my_function"

Run Jest in non-interactive mode:

npx jest --no-coverage 2>&1

Run specific Jest test file:

npx jest tests/foo.test.js

Run Go tests with verbose output:

go test ./... -v 2>&1

Run Cargo tests:

cargo test 2>&1

Run RSpec:

bundle exec rspec --format documentation 2>&1

Pitfalls

• Always run from the project root — relative import paths break if you run from a subdirectory.
• Parse the first failure completely before moving to others. One root cause often fixes many failures.
• Don't skip or delete tests to make a suite pass — fix the underlying code.
• pytest outputs to both stdout and stderr; capture both with 2>&1.
• For Node.js tests, npm test may run in watch mode — prefer npx jest --watchAll=false or npx vitest run.
• Some projects have multiple test suites (unit, integration) — check the scripts section of package.json.

References

• references/pytest.md — pytest markers, common flags, fixture patterns
• references/jest.md — Jest matchers, mocking, common patterns