This project uses a combination of unit tests and end-to-end (e2e) tests to ensure correctness and stability.

• Unit tests are located alongside implementation, with filenames ending in _test.go.
• Currently the preference is to use internal tests i.e. test files do not have _test package suffix.
• Tests use testify for assertions and require statements. Use require when continuing the test is not meaningful, for example it is almost never correct to continue after an error expectation.
• REST mocking is performed with the in-repo MockHTTPClientWithHandlers helpers; GraphQL mocking uses githubv4mock.
• Each tool's schema is snapshotted and checked for changes using the toolsnaps utility (see below).
• Tests are designed to be explicit and verbose to aid maintainability and clarity.
• Handler unit tests should take the form of:
  1. Test tool snapshot
  2. Very important expectations against the schema (e.g. ReadOnly annotation)
  3. Behavioural tests in table-driven form

• E2E tests are located in the e2e/ directory. See the e2e/README.md for full details on running and debugging these tests.

• The toolsnaps utility ensures that the JSON schema for each tool does not change unexpectedly.
• Snapshots are stored in __toolsnaps__/*.snap files, where * represents the name of the tool
• When running tests, the current tool schema is compared to the snapshot. If there is a difference, the test will fail and show a diff.
• If you intentionally change a tool's schema, update the snapshots by running tests with the environment variable: UPDATE_TOOLSNAPS=true go test ./...
• In CI (when GITHUB_ACTIONS=true), missing snapshots will cause a test failure to ensure snapshots are always committed.

• Some tools that mutate global state (e.g., marking all notifications as read) are tested primarily with unit tests, not e2e, to avoid side effects.
• For more on the limitations and philosophy of the e2e suite, see the e2e/README.md.