eslint-plugin-aaa-comments

This plugin provide rule for enforcing AAA (Arrange Act Assert) comments or enforces you to organize your it cases into 3 sections without enforcing comments in unit tests.

For the motivation refer to Making Better Unit Tests: part 1, the AAA pattern.

Installation

# inside your project's working tree
npm install eslint-plugin-aaa-comments --save-dev

Config - Legacy (.eslintrc)

All rules are off by default. Configuring manually:

{
  "rules": {
    "aaa-comments/enforce-aaa-comments": "error"
    // etc...
  },
},

Config - Flat (eslint.config.js)

All rules are off by default. However, you may configure them manually in your eslint.config.(js|cjs|mjs).

import js from '@eslint/js';

export default [
  js.configs.recommended,
  {
    files: ['**/*.{js,mjs,cjs}'],
    languageOptions: {
      ecmaVersion: 'latest',
      sourceType: 'module',
    },
    rules: {
      'aaa-comments/enforce-aaa-comments': 'error',
    },
  },
];

Rules

The package consists of only one single rule

aaa-comments/enforce-aaa-comments

Enforces you to write AAA (Arrange Act Assert) comments in unit tests. How the rule works:

1. Find every it function
2. Find the second argument of the function which is usually a function
3. Within that function calculates how many line breaks does it have

Based on the number of line breaks it callback have:

• If 0 and single statement – passes
• If 0 and more than one statements – fails
• If 1 or 2 line breaks – passes
• If 3 line breaks – requires you to have AAA comments

Examples

Here's passing examples:

it('works', async () => {
  const result = await client.invalidate({ userId: Random.int(1000000) });

  assert.strictEqual(result.isSuccess, true);
});

it('works', async () => {
  const foo = 'bar';

  const result = await client.invalidate({ userId: Random.int(1000000) });

  assert.strictEqual(result.isSuccess, true);
});

it('works', async () => {
  // Arrange
  const foo = 'bar';

  // Act
  const result = await client.invalidate({ userId: Random.int(1000000) });

  const result2 = await client.invalidate({ userId: Random.int(1000001) });

  // Assert
  assert.strictEqual(result.isSuccess, true);
});

Here's examples which are not passing:

it('works', async () => {
  const result = await client.invalidate({ userId: Random.int(1000000) });
  assert.strictEqual(result.isSuccess, true);
});

it('works', async () => {
  const foo = 'bar';

  const result = await client.invalidate({ userId: Random.int(1000000) });

  const result2 = await client.invalidate({ userId: Random.int(1000001) });

  assert.strictEqual(result.isSuccess, true);
});