rule-setup.js

'use strict';

const { readdirSync, readFileSync } = require('fs');
const path = require('path');
const assert = require('chai').assert;
const plugin = require('../..');

const RULE_NAMES = Object.keys(plugin.rules);
const RULE_NAMES_RECOMMENDED = new Set(Object.keys(plugin.configs.recommended.rules));

const MESSAGES = {
  fixable:
    '⚒️ The `--fix` option on the [command line](https://eslint.org/docs/user-guide/command-line-interface#-fix) can automatically fix some of the problems reported by this rule.',
  configRecommended:
    '✔️ The `"extends": "plugin:eslint-plugin/recommended"` property in a configuration file enables this rule.',
  hasSuggestions: '💡 Some problems reported by this rule are manually fixable by editor [suggestions](https://eslint.org/docs/developer-guide/working-with-rules#providing-suggestions).',
};

/**
 * @param {string} string - to operate on
 * @returns the string with a capitalized first letter
 */
function capitalizeFirstLetter (string) {
  return string.charAt(0).toUpperCase() + string.slice(1);
}

describe('rule setup is correct', () => {
  it('should have a list of exported rules and rules directory that match', () => {
    const filePath = path.join(__dirname, '..', 'lib', 'rules');
    const files = readdirSync(filePath);

    assert.deepStrictEqual(
      RULE_NAMES,
      files
        .filter(file => !file.startsWith('.'))
        .map(file => file.replace('.js', ''))
    );
  });

  it('should have tests for all rules', () => {
    const filePath = path.join(__dirname, 'rules');
    const files = readdirSync(filePath);

    assert.deepStrictEqual(
      RULE_NAMES,
      files
        .filter(file => !file.startsWith('.'))
        .map(file => file.replace('.js', ''))
    );
  });

  it('should have documentation for all rules', () => {
    const filePath = path.join(__dirname, '..', '..', 'docs', 'rules');
    const files = readdirSync(filePath);

    assert.deepStrictEqual(
      RULE_NAMES,
      files
        .filter(file => !file.startsWith('.'))
        .map(file => file.replace('.md', ''))
    );
  });

  describe('rule documentation files', () => {
    for (const ruleName of RULE_NAMES) {
      const rule = plugin.rules[ruleName];
      const filePath = path.join(
        __dirname,
        '..',
        '..',
        'docs',
        'rules',
        `${ruleName}.md`
      );
      const fileContents = readFileSync(filePath, 'utf8');
      const lines = fileContents.split('\n');

      describe(ruleName, () => {
        it('should have the right contents (title, notices, etc)', () => {
          // Title
          assert.strictEqual(lines[0], `# ${capitalizeFirstLetter(rule.meta.docs.description)} (${ruleName})`, 'first line has rule description and name');
          assert.strictEqual(lines[1], '', 'second line is blank');

          // Rule Details
          assert.ok(fileContents.includes('## Rule Details'), 'includes "## Rule Details" header');

          // Examples
          assert.ok(fileContents.includes('Examples of **incorrect** code for this rule'), 'includes incorrect examples');
          assert.ok(fileContents.includes('Examples of **correct** code for this rule'), 'includes correct examples');

          // Decide which notices should be shown at the top of the doc.
          const expectedNotices = [];
          const unexpectedNotices = [];
          if (RULE_NAMES_RECOMMENDED.has('eslint-plugin/' + ruleName)) {
            expectedNotices.push('configRecommended');
          } else {
            unexpectedNotices.push('configRecommended');
          }
          if (rule.meta.fixable) {
            expectedNotices.push('fixable');
          } else {
            unexpectedNotices.push('fixable');
          }
          if (rule.meta.hasSuggestions) {
            expectedNotices.push('hasSuggestions');
          } else {
            unexpectedNotices.push('hasSuggestions');
          }

          // Ensure that expected notices are present in the correct order.
          let currentLineNumber = 1;
          for (const expectedNotice of expectedNotices) {
            assert.strictEqual(lines[currentLineNumber], '');
            assert.strictEqual(lines[currentLineNumber + 1], MESSAGES[expectedNotice]);
            currentLineNumber += 2;
          }

          // Ensure that unexpected notices are not present.
          for (const unexpectedNotice of unexpectedNotices) {
            assert.ok(!fileContents.includes(MESSAGES[unexpectedNotice]), 'does not include notice: ' + MESSAGES[unexpectedNotice]);
          }
        });
      });
    }
  });
});