vegan-ipsum/src/util/env.test.ts

Generates passages of vegan-themed placeholder text suitable for use in web pages, graphics, and more. Works in the browser, NodeJS, and React Native.

import ProcessHelper from '../../tests/util/ProcessHelper';
import { SUPPORTED_PLATFORMS } from '../constants';

import { isNode, isReactNative, isWindows } from '.';

/**
 * Unit tests for environment detection utilities ensuring Node, React Native,
 * and Windows detection behave correctly under simulated globals.
 */
describe('environment utilities', () => {
  /**
   * Unit tests for the `isNode` function.
   */
  describe('isNode', () => {
    /**
     * Test case: Should return true if the code is executing in a Node.js environment.
     */
    test('returns true when running in Node.js', () => {
      // Expect `isNode` to return true when running in a Node.js environment
      expect(isNode()).toEqual(true);
    });
  });

  /**
   * Unit tests for the `isReactNative` function.
   */
  describe('isReactNative', () => {
    // Use the shared ProcessHelper to mock and restore `navigator`.
    const process = new ProcessHelper();

    /**
     * Reset the navigator to its original state after each test to avoid side effects.
     * This ensures that changes to `navigator` in one test do not affect others.
     */
    afterEach(() => {
      process.resetNavigator();
    });

    /**
     * Test case: Should return false if the navigator object is not defined or does not indicate React Native.
     */
    test('returns false when not React Native', () => {
      process.setNavigator(undefined);
      // Expect `isReactNative` to return false when `navigator` is undefined
      expect(isReactNative()).toEqual(false);
    });

    /**
     * Test case: Should return true if the navigator object indicates a React Native environment.
     */
    test("returns true when navigator.product === 'ReactNative'", () => {
      process.setNavigator({ product: 'ReactNative' });
      // Expect `isReactNative` to return true when `navigator.product` is set to 'ReactNative'
      expect(isReactNative()).toEqual(true);
    });

    /**
     * Test case: Should return false if accessing navigator throws an error.
     * The try/catch in `isReactNative` should catch and return false instead of bubbling.
     */
    test('returns false when navigator access throws', () => {
      Object.defineProperty(global, 'navigator', {
        get: () => {
          throw new Error('navigator failure');
        },
        configurable: true,
      });
      expect(isReactNative()).toEqual(false);
    });
  });

  /**
   * Unit tests for the `isWindows` function.
   */
  describe('isWindows', () => {
    // Use the shared ProcessHelper to mock and restore `process.platform`.
    const process = new ProcessHelper();

    /**
     * Reset the platform to its original state after each test to avoid side effects.
     * This ensures that changes to `process.platform` in one test do not affect others.
     */
    afterEach(() => {
      process.resetPlatform();
    });

    /**
     * Test case: Should return false if the platform is not Windows.
     */
    test('returns false for non-Windows platform', () => {
      process.setPlatform(SUPPORTED_PLATFORMS.DARWIN);
      // Expect `isWindows` to return false when `process.platform` is set to 'darwin'
      expect(isWindows()).toEqual(false);
    });

    /**
     * Test case: Should return true if the platform is Windows.
     */
    test('returns true for Windows platform', () => {
      process.setPlatform(SUPPORTED_PLATFORMS.WIN32);
      // Expect `isWindows` to return true when `process.platform` is set to 'win32'
      expect(isWindows()).toEqual(true);
    });

    /**
     * Test case: Should return false if the platform is undefined.
     */
    test('returns false when platform undefined', () => {
      process.setPlatform(undefined);
      // Expect `isWindows` to return false when `process.platform` is undefined
      expect(isWindows()).toEqual(false);
    });

    /**
     * Test case: Should return false if accessing `process.platform` throws an error.
     * This triggers the catch block in `isWindows` ensuring safe failure.
     */
    test('returns false when reading platform throws', () => {
      // directly patch the global process object (not the helper)
      Object.defineProperty(global.process, 'platform', {
        get: () => {
          throw new Error('oh no');
        },
        configurable: true,
      });
      // Expect `isWindows` to return false when accessing `process.platform` throws an error
      expect(isWindows()).toEqual(false);
    });
  });
});