eslint-plugin-jest/src/rules/__tests__/prefer-to-have-length.test.js

Eslint rules for Jest

'use strict';

const { RuleTester } = require('eslint');
const rule = require('../prefer-to-have-length');

const ruleTester = new RuleTester();

ruleTester.run('prefer-to-have-length', rule, {
  valid: [
    'expect(files).toHaveLength(1);',
    "expect(files.name).toBe('file');",
    'expect(result).toBe(true);',
    `expect(user.getUserName(5)).resolves.toEqual('Paul')`,
    `expect(user.getUserName(5)).rejects.toEqual('Paul')`,
  ],

  invalid: [
    {
      code: 'expect(files.length).toBe(1);',
      errors: [{ messageId: 'useToHaveLength', column: 22, line: 1 }],
      output: 'expect(files).toHaveLength(1);',
    },
    {
      code: 'expect(files.length).toEqual(1);',
      errors: [{ messageId: 'useToHaveLength', column: 22, line: 1 }],
      output: 'expect(files).toHaveLength(1);',
    },
  ],
});