testing

name	testing
description	Writing tests for eslint-config-greenpie rules. Use when adding tests for new ESLint or oxlint rules, creating fixture files, or verifying rule behavior. Triggers on "write a test", "add test for rule", "test this rule", "create fixture".

Testing Rules in eslint-config-greenpie

Two test categories, each with its own helper and location.

ESLint rules — tests/eslint/__tests__/

Use the programmatic ESLint API with the real config file (do not copy/paste config inline).

import { ESLint } from 'eslint';
import { describe, expect, it } from 'vitest';
import stylisticConfig from '../../../configs/stylistic.js'; // import real config

const RULE_ID = '@stylistic/some-rule';

const eslint = new ESLint({
  overrideConfigFile: null, // null = disable auto-discovery
  overrideConfig: stylisticConfig
});

async function getViolations(code: string) {
  const [result] = await eslint.lintText(code, { filePath: 'test.ts' });
  return result.messages.filter(msg => msg.ruleId === RULE_ID);
}

describe(RULE_ID, () => {
  it('valid: ...', async () => {
    expect(await getViolations('...')).toHaveLength(0);
  });

  it('invalid: ...', async () => {
    expect((await getViolations('...')).length).toBeGreaterThan(0);
  });
});

oxlint rules — tests/oxlint/__tests__/

Use runOxlint + violationsOf from tests/oxlint/helper.ts. Fixture files live next to the test (not in a fixtures/ subfolder).

For Vue fixtures, prefer <script setup lang="ts"> by default. Use Options API only when the rule specifically targets Options API component objects, export default, or legacy option keys.

import path from 'node:path';
import { describe, expect, it } from 'vitest';
import { runOxlint, violationsOf } from '../helper.js';

const RULE_ID = 'plugin/rule-name'; // e.g. 'vitest/consistent-each-for'

describe(RULE_ID, () => {
  it('valid', async () => {
    const diagnostics = await runOxlint([
      path.join(import.meta.dirname, 'rule-name.valid.ts')
    ]);

    expect(violationsOf(diagnostics, RULE_ID)).toHaveLength(0);
  });

  it('invalid', async () => {
    const diagnostics = await runOxlint([
      path.join(import.meta.dirname, 'rule-name.invalid.ts')
    ]);

    expect(violationsOf(diagnostics, RULE_ID).length).toBeGreaterThan(0);
  });
});

Type-aware rules (typescript/ prefix)

Type-aware oxlint rules are enabled by default via options.typeAware: true in the shared config. No special options needed:

const diagnostics = await runOxlint([
  path.join(import.meta.dirname, 'dot-notation.valid.ts')
]);

Type-aware rules require a tsconfig.json in tests/oxlint/__tests__/ for tsgolint auto-discovery. This file already exists — do not create a new one per rule.

Fixture filenames

Must match the ignore patterns in configs/oxlintrc.jsonc so npm run lint:oxlint:agent and npm run lint:eslint skip them:

• rule-name.valid.ts
• rule-name.invalid.ts

violationsOf mapping

violationsOf(diagnostics, ruleId) converts:

• plugin/rule-name → eslint-plugin-plugin(rule-name)
• rule-name → eslint(rule-name)
• typescript/rule-name → also matches typescript-eslint(rule-name) (tsgolint's diagnostic code format for type-aware rules)

After writing tests

npm run lint:oxlint:agent
npm run lint:eslint
npm run test:agent

All must pass.