Linter

Contributing New Rules

See the adding rules guide for how to add new rules to Oxlint.

Development

Create a ./test.ts and then

just watch "cargo run --bin oxlint -- test.ts"

Or test and filter against the rule:

just watch "cargo test -p oxc_linter -- rule-name"

Testing oxlint against a full codebase

To test oxlint on a full codebase, for example to test your changes with a large JavaScript/TypeScript project, you can build the oxlint CLI and run it against that codebase.

# build the oxlint cli in the oxc repo
just oxlint-node
# and then in the directory of the codebase you want to test with, run oxlint with node:
node <path-to-oxc-repo>/apps/oxlint/dist/cli.js
# You can also pass flags to it, like -D to enable a specific rule, and --disable-x-plugin to turn off default plugins:
node <path-to-oxc-repo>/apps/oxlint/dist/cli.js -D rulename --disable-unicorn-plugin --disable-oxc-plugin --disable-typescript-plugin

Snapshot Testing

cargo insta is used for snapshot testing.

After running cargo test -p oxc_linter and the line Tester::new(RULE::NAME, pass, fail).test_and_snapshot() is called, a new rule.snap.new file will be generated.

Use cargo insta accept to accept all snapshot changes.

Rule Category

• correctness - code that is outright wrong or useless
• suspicious - code that is most likely wrong or useless
• pedantic - lints which are rather strict or have occasional false positives
• perf - code that can be written to run faster
• style - code that should be written in a more idiomatic way
• restriction - lints should be considered on a case-by-case basis before enabling.
• nursery - new lints that are still under development