ankyr-testing

Mock only external boundaries like network calls, clocks, subprocesses, and version control operations. Never mock the code under test or its private helpers; instead drive those paths through the public API or extract a seam you own and fake that.

A fake is an in-process stand-in with the same interface, such as an in-memory store or temp clock. A mock records calls and returns scripted values. Fakes catch more contract drift, so prefer them for file, YAML, or JSON collaborators.

Use a mock when the collaborator is a remote API or git process, when you only need to confirm a call happened, or when constructing the real type requires network access. Otherwise prefer fakes or real temp files.

Write exactly one regression test per bug fix. The test must fail if the fix is reverted, proving it actually covers the bug rather than passing regardless of the code under test.

A failing test must exit with a non-zero status code or the build system cannot detect it. Runner-less suites must call process.exit(1) or sys.exit(1) explicitly; a script that prints FAIL and exits 0 is invisible to CI.

Yes, the core rules are language-agnostic and apply to any test suite. Runner and library specifics live in the matching language skill's references/testing.md file for Python or Node.js.