haskell-language-server/CONTRIBUTING.md

Contributors Guide

Pre-commit hook

We are using pre-commit-hook.nix to configure git pre-commit hook for formatting. Although it is possible to run formatting manually, we recommend you to use it to set pre-commit hook as our CI checks pre-commit hook is applied or not.

You can configure the pre-commit-hook by running

nix-shell

If you don't want to use nix, you can instead use pre-commit with the following config.

{
  "repos": [
    {
      "hooks": [
        {
          "entry": "stylish-haskell --inplace",
          "exclude": "(^Setup.hs$|test/testdata/.*$|test/data/.*$|^hie-compat/.*$|^plugins/hls-tactics-plugin/.*$)",
          "files": "\\.l?hs$",
          "id": "stylish-haskell",
          "language": "system",
          "name": "stylish-haskell",
          "pass_filenames": true,
          "types": [
            "file"
          ]
        }
      ],
      "repo": "local"
    }
  ]
}

Why they are excluded?

• test/testdata and test/data are there as we want to test formatting plugins.
• hie-compat is there as we want to keep its code as close to GHC as possible.
• hls-tactics-plugin is there as the main contributor of the plugin (@isovector) does not want auto-formatting.

Testing

The tests make use of the Tasty test framework.

There are two test suites, functional tests, and wrapper tests.

Testing with Cabal

Running all the tests

$ cabal test

Running just the functional tests

$ cabal test func-test

Running just the wrapper tests

$ cabal test wrapper-test

Running a subset of tests

Tasty supports providing Patterns as command line arguments, to select the specific tests to run.

$ cabal test func-test --test-option "-p hlint"

The above recompiles everything every time you use a different test option though.

An alternative is

$ cabal run haskell-language-server:func-test -- -p "hlint enables"