Code quality#

See also

Complete dev install instructions before continuing.

We have several tools configured for checking code quality:

  • Pre-commit checks run automatically at commit time. Install checks with pre-commit install. Run them manually with pre-commit run --all-files. Will exit non-zero when finding errors or changing files.

    • Ruff formats and lints (sometimes autofixes) Python code.

    • Generic pre-commit checks help avoid common mistakes like committing large files or trailing whitespace.

  • Formatting and lint checks and autofixers for Typescript, Javascript, CSS, JSON, Markdown, and YAML. Defined as package scripts (in package.json). Run manually with jlpm run lint. Will exit 0 when applying fixes. Check the logs and/or git status after every run.

    • Prettier formats the file types listed above.

    • Eslint lints (sometimes autofixes) JS/TS code.

  • UI tests using Galata, defined in the ui-tests/ directory.

    Warning

    Some UI tests depend on snapshot (screenshot) comparison, which depends strongly on the system used to generate the snapshots. Variables like GPU, operating system, display scaling, and more can affect the outcome of snapshot testing. The instructions below will skip snapshot tests for this reason. Please do not run snapshot tests locally and instead rely on CI (GitHub Actions).

    To run locally:

    cd ui-tests
jlpm install             # If you haven't already
jlpm playwright install  # If you haven't already
jlpm run test:local      # Or, to test in jupyterlite, run `test:locallite`

    • DOM testing: Interact with the application programmatically and verify resulting DOM looks correct.

    • Snapshot testing: Interact with the application programmatically and verify the resulting rendered content exactly matches snapshots in this repository. When snapshot tests fail, new snapshots can be generated by commenting please update snapshots in a PR or locally running jlpm run test:update from the ui-tests/ directory. Please carefully verify the snapshot changes are as expected before merging.

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