tessl/npm-eslint-plugin-mocha

ESLint plugin providing 24 rules for Mocha testing framework best practices and error detection.

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Test Quality Rules

Name: tessl/npm-eslint-plugin-mocha
Author: tessl

Rules that enforce test code quality, readability, and maintainability practices in Mocha test suites.

Capabilities

No Identical Title Rule

Prevents identical test titles within the same test suite, improving test readability and debugging.

/**
 * Disallows identical test titles in the same suite
 * Helps identify duplicate or poorly named tests
 */
const noIdenticalTitleRule = {
  meta: {
    type: 'problem',
    docs: {
      description: 'Disallow identical titles',
      url: 'https://github.com/lo1tuma/eslint-plugin-mocha/blob/master/docs/rules/no-identical-title.md'
    },
    schema: []
  },
  create: (context) => ESLintVisitor
};

Usage:

{
  "rules": {
    "mocha/no-identical-title": "error"
  }
}

No Empty Description Rule

Ensures all tests have meaningful descriptions, preventing empty or whitespace-only test names.

/**
 * Disallows empty test descriptions
 * Enforces meaningful test naming for better documentation
 */
const noEmptyDescriptionRule = {
  meta: {
    type: 'problem',
    docs: {
      description: 'Disallow empty test descriptions',
      url: 'https://github.com/lo1tuma/eslint-plugin-mocha/blob/master/docs/rules/no-empty-description.md'
    },
    schema: []
  },
  create: (context) => ESLintVisitor
};

Usage:

{
  "rules": {
    "mocha/no-empty-description": "error"
  }
}

Valid Test Description Rule

Validates test description format according to configurable patterns and conventions.

/**
 * Validates test description format
 * Configurable pattern matching for consistent test naming
 */
const validTestDescriptionRule = {
  meta: {
    type: 'suggestion',
    docs: {
      description: 'Require valid test descriptions',
      url: 'https://github.com/lo1tuma/eslint-plugin-mocha/blob/master/docs/rules/valid-test-description.md'
    },
    schema: [{
      type: 'object',
      properties: {
        pattern: { type: 'string' },
        testNames: { 
          type: 'array',
          items: { type: 'string' }
        },
        message: { type: 'string' }
      },
      additionalProperties: false
    }]
  },
  create: (context) => ESLintVisitor
};

Usage:

{
  "rules": {
    "mocha/valid-test-description": ["error", {
      "pattern": "^should .+$",
      "message": "Test description must start with 'should'"
    }]
  }
}

Valid Suite Description Rule

Validates suite (describe block) description format according to configurable patterns.

/**
 * Validates suite description format
 * Configurable pattern matching for consistent suite naming
 */
const validSuiteDescriptionRule = {
  meta: {
    type: 'suggestion',
    docs: {
      description: 'Require valid suite descriptions',
      url: 'https://github.com/lo1tuma/eslint-plugin-mocha/blob/master/docs/rules/valid-suite-description.md'
    },
    schema: [{
      type: 'object',
      properties: {
        pattern: { type: 'string' },
        suiteNames: { 
          type: 'array',
          items: { type: 'string' }
        },
        message: { type: 'string' }
      },
      additionalProperties: false
    }]
  },
  create: (context) => ESLintVisitor
};

Usage:

{
  "rules": {
    "mocha/valid-suite-description": ["error", {
      "pattern": "^[A-Z].*$",
      "message": "Suite description must start with uppercase letter"
    }]
  }
}

Consistent Spacing Between Blocks Rule

Enforces consistent spacing between test blocks for improved readability.

/**
 * Enforces consistent spacing between test blocks
 * Improves visual separation and code readability
 */
const consistentSpacingRule = {
  meta: {
    type: 'layout',
    docs: {
      description: 'Require consistent spacing between blocks',
      url: 'https://github.com/lo1tuma/eslint-plugin-mocha/blob/master/docs/rules/consistent-spacing-between-blocks.md'
    },
    fixable: 'whitespace',
    schema: []
  },
  create: (context) => ESLintVisitor
};

Usage:

{
  "rules": {
    "mocha/consistent-spacing-between-blocks": "error"
  }
}

Max Top Level Suites Rule

Limits the number of top-level test suites per file to improve test organization.

/**
 * Limits the number of top-level test suites
 * Encourages better test file organization
 */
const maxTopLevelSuitesRule = {
  meta: {
    type: 'suggestion',
    docs: {
      description: 'Limit the number of top-level suites',
      url: 'https://github.com/lo1tuma/eslint-plugin-mocha/blob/master/docs/rules/max-top-level-suites.md'
    },
    schema: [{
      type: 'object',
      properties: {
        limit: { 
          type: 'integer',
          minimum: 1
        }
      },
      additionalProperties: false
    }]
  },
  create: (context) => ESLintVisitor
};

Usage:

{
  "rules": {
    "mocha/max-top-level-suites": ["error", { "limit": 1 }]
  }
}

Usage Examples

Comprehensive Quality Setup

{
  "rules": {
    "mocha/no-identical-title": "error",
    "mocha/no-empty-description": "error",
    "mocha/valid-test-description": ["error", {
      "pattern": "^should (have|be|do|return|throw|call|not) .+$",
      "message": "Test should describe expected behavior"
    }],
    "mocha/valid-suite-description": ["error", {
      "pattern": "^[A-Z][a-zA-Z0-9\\s]*$",
      "message": "Suite should start with uppercase and contain only letters, numbers, and spaces"
    }],
    "mocha/consistent-spacing-between-blocks": "error",
    "mocha/max-top-level-suites": ["error", { "limit": 1 }]
  }
}

Pattern Examples

// ✓ Valid test descriptions with pattern "^should .+$"
it('should return correct result', function() {});
it('should throw error for invalid input', function() {});

// ✗ Invalid test descriptions
it('returns result', function() {}); // Missing 'should'
it('', function() {}); // Empty description

// ✓ Valid suite descriptions with uppercase start
describe('UserService', function() {});
describe('Authentication module', function() {});

// ✗ Invalid suite descriptions  
describe('userService', function() {}); // Lowercase start
describe('', function() {}); // Empty description