TREK/client/tests/unit/scripts/eslint-ratchet.test.ts

import { mkdirSync, mkdtempSync, readFileSync, rmSync, writeFileSync } from 'node:fs';
import { tmpdir } from 'node:os';
import { join } from 'node:path';
import { afterEach, describe, expect, it } from 'vitest';
import {
  areaCounts,
  check,
  inlineConfigsOf,
  lintClient,
  newWarningsOf,
  tally,
} from '../../../scripts/lib/eslint-warnings.mjs';
import { RatchetError } from '../../../scripts/lib/ratchet.mjs';
import { ratchetTree, type RatchetTree } from '../../helpers/ratchetFixture';

let tree: RatchetTree;
afterEach(() => tree?.remove());

const BASELINE = 'scripts/eslint-baseline.json';

interface Message {
  ruleId: string | null;
  severity: number;
  message?: string;
  fatal?: boolean;
  line?: number;
  column?: number;
}

const warn = (ruleId: string | null, message = 'm'): Message => ({ ruleId, severity: 1, message });

function result(root: string, key: string, messages: Message[], suppressed: Message[] = []) {
  return {
    filePath: join(root, key),
    messages: messages.map((m) => ({ message: 'm', ...m })),
    suppressedMessages: suppressed.map((m) => ({ message: 'm', ...m })),
  };
}

const empty = { src: {}, tests: {}, suppressed: {} };

async function run(baseline: object, results: (root: string) => ReturnType<typeof result>[], update = false) {
  tree = ratchetTree({ [BASELINE]: JSON.stringify(baseline) });
  return check({
    root: tree.root,
    baselinePath: tree.path(BASELINE),
    update,
    lint: async (root: string) => results(root),
    ...tree.out,
  });
}

describe('lint:warnings', () => {
  it('ESLINT-001: counts warnings per rule for app code, tests and suppressed messages', () => {
    const root = join('/r');
    const { counts, files, errors } = tally(
      [
        result(
          root,
          'src/a.tsx',
          [warn('no-empty'), warn('no-empty'), warn(null, 'Unused eslint-disable directive')],
          [warn('react-hooks/exhaustive-deps')]
        ),
        result(root, 'src/a.test.tsx', [warn('@typescript-eslint/no-explicit-any')]),
        result(root, 'tests/unit/b.ts', [warn('@typescript-eslint/no-explicit-any')]),
      ],
      root
    );
    expect(counts).toEqual({
      src: { 'no-empty': 2, 'unused-disable-directive': 1 },
      tests: { '@typescript-eslint/no-explicit-any': 2 },
      suppressed: { 'react-hooks/exhaustive-deps': 1 },
    });
    expect(files.src['no-empty']).toEqual({ 'src/a.tsx': 2 });
    expect(errors).toEqual([]);
  });

  it('ESLINT-002: passes when every count sits at its entry', async () => {
    const code = await run({ ...empty, src: { 'no-empty': 1 } }, (root) => [
      result(root, 'src/a.ts', [warn('no-empty')]),
    ]);
    expect(code).toBe(0);
  });

  it('ESLINT-010: fails a count that fell below its entry, or a rule with none left, until --update', async () => {
    const baseline = { ...empty, src: { 'no-empty': 2 }, suppressed: { 'react-hooks/exhaustive-deps': 1 } };
    const results = (root: string) => [result(root, 'src/a.ts', [warn('no-empty')])];
    expect(await run(baseline, results)).toBe(1);
    const out = tree.error.join('\n');
    expect(out).toMatch(/src: no-empty is held at 2 in scripts\/eslint-baseline\.json, but there are 1 now/);
    expect(out).toMatch(/suppressed: react-hooks\/exhaustive-deps is held at 1 .*but there are 0 now/);
    expect(out).toMatch(/npm run lint:warnings -- --update/);
    tree.remove();
    expect(await run(baseline, results, true)).toBe(0);
  });

  it('ESLINT-003: fails a new warning and names the files behind it', async () => {
    const code = await run({ ...empty, src: { 'no-empty': 1 } }, (root) => [
      result(root, 'src/a.ts', [warn('no-empty')]),
      result(root, 'src/b.ts', [warn('no-empty')]),
    ]);
    expect(code).toBe(1);
    expect(tree.error.join('\n')).toMatch(
      /src: 2 no-empty warning\(s\), baseline 1\. Most in: src\/a\.ts \(1\), src\/b\.ts \(1\)/
    );
  });

  it('ESLINT-004: an eslint-disable comment does not get a warning past the ratchet', async () => {
    const code = await run(empty, (root) => [result(root, 'src/a.ts', [], [warn('react-hooks/exhaustive-deps')])]);
    expect(code).toBe(1);
    expect(tree.error.join('\n')).toMatch(/suppressed: 1 react-hooks\/exhaustive-deps warning/);
  });

  it('ESLINT-005: app code cannot spend the headroom the tests left', async () => {
    const code = await run({ ...empty, tests: { 'no-empty': 5 } }, (root) => [
      result(root, 'src/a.ts', [warn('no-empty')]),
    ]);
    expect(code).toBe(1);
  });

  it('ESLINT-006: any error fails, a parse failure included', async () => {
    const code = await run(empty, (root) => [
      result(root, 'src/a.ts', [
        { ruleId: null, severity: 2, fatal: true, message: 'Parsing error', line: 3, column: 1 },
      ]),
    ]);
    expect(code).toBe(1);
    expect(tree.error.join('\n')).toMatch(/src\/a\.ts:3:1 {2}Parsing error/);
  });

  it('ESLINT-007: --update lowers and drops counts and never raises one', async () => {
    await run(
      { src: { 'no-empty': 3, 'no-useless-escape': 1 }, tests: {}, suppressed: {} },
      (root) => [result(root, 'src/a.ts', [warn('no-empty'), warn('no-unused-vars')])],
      true
    );
    expect(JSON.parse(readFileSync(tree.path(BASELINE), 'utf8'))).toEqual({
      src: { 'no-empty': 1 },
      suppressed: {},
      tests: {},
    });
  });

  it('ESLINT-008: a baseline without all three areas, or with a stray one, stops the check', async () => {
    expect(areaCounts({ src: {}, tests: {} })).toMatch(/"suppressed" area is missing/);
    expect(areaCounts({ ...empty, other: {} })).toMatch(/"other" is not one of/);
    expect(areaCounts({ ...empty, src: { a: -1 } })).toMatch(/in "src"/);
    await expect(run({ src: {} }, () => [])).rejects.toThrow(RatchetError);
  });

  it('ESLINT-009: finds the block comments that configure a rule, and nothing in strings, templates or regexes', () => {
    const source = [
      '/* eslint @typescript-eslint/no-explicit-any: off */',
      'const a = "/* eslint no-empty: off */";',
      'const b = `${a} /* eslint no-empty: off */`;',
      '/* eslint-disable no-empty */',
      '/*eslint no-empty:0*/ const c = <div>{/* eslint no-empty: 1 */}</div>;',
      'const r = /\\/\\* eslint no-empty/;',
      '// eslint no-empty: off',
      '/** eslint is the linter */',
    ].join('\n');
    expect(inlineConfigsOf(source, 'src/a.tsx')).toEqual([
      '1:1  /* eslint @typescript-eslint/no-explicit-any: off */',
      '5:1  /*eslint no-empty:0*/',
      '5:39  /* eslint no-empty: 1 */',
    ]);
    expect(inlineConfigsOf('export const a = 1 /* eslint no-empty: off */\n', 'src/a.ts')).toHaveLength(1);
    expect(inlineConfigsOf('export const a = 1\n', 'src/a.ts')).toEqual([]);
  });

  it('ESLINT-010: an inline rule config fails the check although it leaves no message behind', async () => {
    const code = await run(empty, (root) => [
      { ...result(root, 'src/a.ts', []), inlineConfigs: ['1:1  /* eslint no-empty: off */'] },
    ]);
    expect(code).toBe(1);
    expect(tree.error.join('\n')).toMatch(
      /src\/a\.ts:1:1 {2}\/\* eslint no-empty: off \*\/ {2}configures a rule inline/
    );
  });

  it('ESLINT-011: lintClient reads the inline rule configs of every file it lints', async () => {
    tree = ratchetTree({
      'eslint.config.mjs': "export default [{ files: ['**/*.js'], rules: { 'no-empty': 'warn' } }];\n",
      'src/a.js': '/* eslint no-empty: off */\nif (globalThis.x) {}\n',
      'src/b.js': 'if (globalThis.x) {}\n',
    });
    const results = await lintClient(tree.root);
    const byKey = Object.fromEntries(results.map((r) => [r.filePath.split('\\').join('/').split('/src/')[1], r]));
    expect(byKey['a.js'].messages).toEqual([]);
    expect(byKey['a.js'].inlineConfigs).toEqual(['1:1  /* eslint no-empty: off */']);
    expect(byKey['b.js'].messages.map((m) => m.ruleId)).toEqual(['no-empty']);
    expect(byKey['b.js'].inlineConfigs).toEqual([]);
  });

  it('names the file and line behind a grown count, measured against the base, and nothing without one', async () => {
    const root = mkdtempSync(join(tmpdir(), 'lint-new-'));
    try {
      mkdirSync(join(root, 'src'));
      writeFileSync(join(root, 'src/new.ts'), 'two');
      writeFileSync(join(root, 'src/old.ts'), 'one');
      // new.ts held none of the rule on the base, old.ts already held its one
      const git = (_root: string, args: string[]) =>
        args[0] === 'diff' ? 'src/new.ts\nsrc/old.ts\n' : args[1]?.endsWith('old.ts') ? 'one' : 'none';
      const counts: Record<string, number> = { two: 2, one: 1, none: 0 };
      const lintText = async (text: string) => [
        {
          messages: Array.from({ length: counts[text] ?? 0 }, (_, i) => ({
            ruleId: 'no-empty',
            severity: 1,
            message: `w${i}`,
            line: i + 1,
          })),
        },
      ];
      const keys = ['src/new.ts', 'src/old.ts', 'src/untouched.ts'];
      const lines = await newWarningsOf({ root, rule: 'no-empty', area: 'src', keys, lintText, ref: 'base', git });
      expect(lines).toEqual(['src/new.ts:1  w0', 'src/new.ts:2  w1']);
      expect(await newWarningsOf({ root, rule: 'no-empty', area: 'src', keys, lintText, git: () => null })).toBeNull();
    } finally {
      rmSync(root, { recursive: true, force: true });
    }
  });
});