next.js/test/unit/eslint-plugin-next/no-assign-module-variable.test.ts

import { RuleTester as ESLintTesterV8 } from 'eslint-v8'
import { RuleTester as ESLintTesterV9 } from 'eslint'
import { rules } from '@next/eslint-plugin-next'

const NextESLintRule = rules['no-assign-module-variable']

const tests = {
  valid: [
    `
      let myModule = {};

      export default function MyComponent() {
        return <></>
      }
    `,
  ],
  invalid: [
    {
      code: `
      let module = {};

      export default function MyComponent() {
        return <></>
      }
      `,
      errors: [
        {
          message:
            'Do not assign to the variable `module`. See: https://nextjs.org/docs/messages/no-assign-module-variable',
        },
      ],
    },
  ],
}

describe('no-assign-module-variable', () => {
  new ESLintTesterV8({
    parserOptions: {
      ecmaVersion: 2018,
      sourceType: 'module',
      ecmaFeatures: {
        modules: true,
        jsx: true,
      },
    },
  }).run('eslint-v8', NextESLintRule, tests)

  new ESLintTesterV9({
    languageOptions: {
      ecmaVersion: 2018,
      sourceType: 'module',
      parserOptions: {
        ecmaFeatures: {
          modules: true,
          jsx: true,
        },
      },
    },
  }).run('eslint-v9', NextESLintRule, tests)
})