test(linter): Add JSON Schema validation tests for oxlintrc configuration

[Copilot]

• Add jsonschema crate as dev-dependency to oxc_linter/Cargo.toml
• Create test fixture directory for schema validation tests
• Create valid test configuration files
  • Basic valid config with plugins
  • Config with valid categories
  • Full featured valid config (from issue) with jsPlugins
  • Environment config
  • Rules config
  • Ignore patterns config with glob patterns
  • Empty config
• Create invalid test configuration files
  • Config with invalid plugin name
  • Config with invalid category name
  • Config with invalid severity
  • Config with wrong type for plugins
  • Config with wrong type for env
• Create schema validation test file
  • Test that loads the generated schema
  • Tests valid configs pass validation
  • Tests invalid configs fail validation
  • Test that schema is valid JSON Schema Draft 7
• Run and verify tests work correctly
• Clean up accidentally committed files
• Format code per project standards
• Address code review feedback
• Fix all clippy warnings

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[codspeed-hq]

CodSpeed Performance Report

Merging #16822 will not alter performance

_{Comparing copilot/add-json-schema-tests (decfb4e) with main (bc7aae7)¹}

Summary

✅ 42 untouched
⏩ 3 skipped²

Footnotes

1. No successful run was found on main (7005873) during the generation of this report, so bc7aae7 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[connorshea]

This looks good to me generally, but I also did part of the work, so can't really approve :)

[charliecreates]

The test suite adds valuable schema regression coverage, but it currently relies on npm/oxlint/configuration_schema.json existing at test time, which can make cargo test non-hermetic and flaky in CI or clean checkouts. The insta snapshots also capture unstable, dependency-version-sensitive jsonschema error strings, which may cause noisy churn. Consider adding a runtime fallback (or explicit precondition) for schema loading and snapshot a more stable, sorted representation of validation errors.

Additional notes (2)

• Readability | crates/oxc_linter/tests/schema_validation_test.rs:14-32
get_project_root().unwrap() is called multiple times. In tests this is fine, but it also means failures will be less informative and you’ll do redundant filesystem work. Consolidating to a single project_root() helper improves readability and makes it easier to change behavior (e.g., fallback logic) in one place.

• Maintainability | crates/oxc_linter/tests/schema_validation_test.rs:111-126
snap_name currently includes the .json extension (e.g. invalid_env_wrong_type.json_errors). That’s not wrong, but it’s a bit noisy and makes renames (like switching fixtures to .jsonc in the future) cause snapshot churn. Also, snapshot naming depends on the filename string rather than the path, which becomes awkward if you later enumerate fixtures from the directory.

Summary of changes

What changed

✅ Added JSON Schema validation coverage for .oxlintrc

• Introduced a new Rust test suite at crates/oxc_linter/tests/schema_validation_test.rs that:
  • Loads the JSON Schema from npm/oxlint/configuration_schema.json.
  • Validates a curated set of valid and invalid config fixtures.
  • Snapshots invalid validation output via insta for stable regression tracking.
  • Verifies the schema declares Draft 7 via the $schema field and is compilable.

🧪 Added fixtures + snapshots

• Added fixture files under:
  • crates/oxc_linter/tests/fixtures/schema_validation/valid/*.json
  • crates/oxc_linter/tests/fixtures/schema_validation/invalid/*.json
• Added insta snapshot files under crates/oxc_linter/tests/snapshots/* capturing failing validation results.

📦 Dependency + repo hygiene updates

• Added jsonschema = "0.37" as a dev-dependency in crates/oxc_linter/Cargo.toml.
• Updated .gitignore to ignore *.rlib.

[Copilot]

Pull request overview

This PR adds comprehensive JSON Schema validation tests for the oxlintrc configuration file to prevent regressions in the schema generation process. The tests validate both valid and invalid configuration files against the generated schema, ensuring that the schema correctly accepts proper configs and rejects improper ones.

Key changes:

• Added jsonschema crate as a dev-dependency for schema validation testing
• Created 11 valid test fixtures covering various configuration scenarios (plugins, categories, environments, rules, overrides, etc.)
• Created 7 invalid test fixtures testing common misconfiguration errors
• Implemented 3 test functions with snapshot testing for validation errors
• Updated .gitignore to exclude *.rlib build artifacts

Reviewed changes

Copilot reviewed 27 out of 29 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/oxc_linter/Cargo.toml	Adds jsonschema dev-dependency for validation testing
crates/oxc_linter/tests/schema_validation_test.rs	Implements schema validation tests with fixture loading and snapshot testing
crates/oxc_linter/tests/fixtures/schema_validation/valid/*.json	Provides 11 valid configuration test cases covering different features
crates/oxc_linter/tests/fixtures/schema_validation/invalid/*.json	Provides 7 invalid configuration test cases for error validation
crates/oxc_linter/tests/snapshots/invalid_*.snap	Snapshot files capturing expected validation error messages
.gitignore	Adds *.rlib to ignore Rust library build artifacts
Cargo.lock	Updates lock file with jsonschema and its transitive dependencies

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[connorshea]

I'm going to close this for now, I think it's worth exploring later though