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Testing i18n Locale Resolution Implementation in dcloudio/uni-app

This test suite validates the i18n locale resolution functionality in uni-app, focusing on language fallback mechanisms and locale handling. The tests verify proper locale selection based on specified preferences and fallback scenarios across different platform contexts.

Test Coverage Overview

The test suite provides comprehensive coverage of the resolveI18nLocale function, examining various locale resolution scenarios.

Tests explicit locale specification
Validates English fallback behavior for app and mp platforms
Verifies Chinese language variant handling (zh-Hans, zh-Hant)
Confirms default fallback to first available locale

Implementation Analysis

The implementation utilizes Jest’s describe/test structure for organized test grouping. Each test case employs expect().toBe() assertions to verify exact locale string matching.

The testing pattern follows AAA (Arrange-Act-Assert) with consistent input parameters: platform type, available locales array, and optional preferred locale.

Technical Details

Testing Framework: Jest
Language: TypeScript
Test Structure: Unit tests with individual cases
File Location: packages/uni-cli-shared/__tests__/
Key Dependencies: resolveI18nLocale function from i18n module

Best Practices Demonstrated

The test suite exemplifies clean testing practices with clear test case isolation and descriptive naming conventions.

Consistent test structure and naming
Focused test cases with single responsibility
Comprehensive edge case coverage
Clear separation of platform-specific behavior

dcloudio/uni-app

packages/uni-cli-shared/__tests__/i18n.spec.ts

            
import { resolveI18nLocale } from '../src/i18n'
describe('resolveI18nLocale', () => {
  test('specifying locale', () => {
    expect(resolveI18nLocale('app', ['zh-Hans', 'fr'], 'fr')).toBe('fr')
  })
  test('fallback en(app)', () => {
    expect(resolveI18nLocale('app', ['zh-Hans', 'en'], 'fr')).toBe('en')
  })
  test('fallback en(mp)', () => {
    expect(resolveI18nLocale('mp-weixin', ['zh-Hans', 'en'], 'fr')).toBe(
      'zh-Hans'
    )
  })
  test('fallback zh-Hans', () => {
    expect(resolveI18nLocale('app', ['zh-Hans', 'es'])).toBe('zh-Hans')
  })
  test('fallback zh-Hant', () => {
    expect(resolveI18nLocale('app', ['zh-Hant', 'es'])).toBe('zh-Hant')
  })
  test('fallback first locale', () => {
    expect(resolveI18nLocale('app', ['fr', 'es'])).toBe('fr')
  })
})