|
| 1 | +--- |
| 2 | +applyTo: 'src/renderer/src/**/*.test.tsx' |
| 3 | +--- |
| 4 | + |
| 5 | +# Hook Testing Guide |
| 6 | + |
| 7 | +## Scope |
| 8 | + |
| 9 | +These instructions cover writing Jest tests for React hooks in the renderer application under `src/renderer/src`. This guide addresses the specific challenges and patterns encountered in this project's testing environment. |
| 10 | + |
| 11 | +## Key Testing Challenges in This Project |
| 12 | + |
| 13 | +### 1. Complex Dependency Chains |
| 14 | + |
| 15 | +- Many hooks import contexts that have deep dependency trees leading to problematic modules like `react-localization` |
| 16 | +- Direct context provider usage in tests can cause "Cannot use import statement outside a module" errors |
| 17 | +- Solution: Mock dependencies comprehensively rather than trying to provide real context |
| 18 | + |
| 19 | +### 2. Context Dependencies |
| 20 | + |
| 21 | +- Hooks often depend on contexts like `PlanContext`, `GlobalContext`, etc. |
| 22 | +- These contexts import Redux stores, localization, and other complex dependencies |
| 23 | +- Solution: Mock `useContext` directly instead of trying to provide context values |
| 24 | + |
| 25 | +## Testing Pattern for Hooks |
| 26 | + |
| 27 | +### Basic Test Structure |
| 28 | + |
| 29 | +```typescript |
| 30 | +import { renderHook } from '@testing-library/react'; |
| 31 | +import React from 'react'; |
| 32 | + |
| 33 | +// Mock dependencies BEFORE importing the hook |
| 34 | +jest.mock('react', () => ({ |
| 35 | + ...jest.requireActual('react'), |
| 36 | + useContext: jest.fn(), |
| 37 | + useMemo: jest.fn(), |
| 38 | + // Add other React hooks as needed |
| 39 | +})); |
| 40 | + |
| 41 | +jest.mock('../../context/useGlobal', () => ({ |
| 42 | + useGlobal: jest.fn(), |
| 43 | +})); |
| 44 | + |
| 45 | +jest.mock('../../crud', () => ({ |
| 46 | + // Mock all crud functions the hook uses |
| 47 | + findRecord: jest.fn(), |
| 48 | + sectionDescription: jest.fn(), |
| 49 | +})); |
| 50 | + |
| 51 | +// Import the hook AFTER mocking |
| 52 | +import { useYourHook } from './useYourHook'; |
| 53 | + |
| 54 | +// Get references to mocked functions |
| 55 | +const { useContext, useMemo } = React; |
| 56 | +const { useGlobal } = require('../../context/useGlobal'); |
| 57 | +const { findRecord } = require('../../crud'); |
| 58 | +``` |
| 59 | + |
| 60 | +### Mock Setup Pattern |
| 61 | + |
| 62 | +```typescript |
| 63 | +describe('useYourHook', () => { |
| 64 | + const mockContextValue = { |
| 65 | + // Mock context state structure |
| 66 | + state: { |
| 67 | + sectionArr: [[1, 'Section One']], |
| 68 | + }, |
| 69 | + }; |
| 70 | + |
| 71 | + beforeEach(() => { |
| 72 | + jest.clearAllMocks(); |
| 73 | + |
| 74 | + // Setup default mocks |
| 75 | + (useGlobal as jest.Mock).mockReturnValue([mockMemory, jest.fn()]); |
| 76 | + (useContext as jest.Mock).mockReturnValue(mockContextValue); |
| 77 | + (findRecord as jest.Mock).mockReturnValue(undefined); |
| 78 | + |
| 79 | + // Mock useMemo to return the factory result directly |
| 80 | + (useMemo as jest.Mock).mockImplementation((factory) => factory()); |
| 81 | + }); |
| 82 | +}); |
| 83 | +``` |
| 84 | + |
| 85 | +## Comprehensive Mocking Strategy |
| 86 | + |
| 87 | +### Required Mocks |
| 88 | + |
| 89 | +1. **React hooks**: `useContext`, `useMemo`, `useCallback`, etc. |
| 90 | +2. **Custom contexts**: `useGlobal`, context imports |
| 91 | +3. **CRUD functions**: Any imported utility functions |
| 92 | +4. **Model imports**: Usually work fine, but mock if causing issues |
| 93 | + |
| 94 | +### Mock Context Providers |
| 95 | + |
| 96 | +Instead of creating context providers, mock `useContext` directly: |
| 97 | + |
| 98 | +```typescript |
| 99 | +// DON'T do this (causes dependency issues): |
| 100 | +const Wrapper = ({ children }) => ( |
| 101 | + <PlanContext.Provider value={mockValue}> |
| 102 | + {children} |
| 103 | + </PlanContext.Provider> |
| 104 | +); |
| 105 | + |
| 106 | +// DO this instead: |
| 107 | +(useContext as jest.Mock).mockReturnValue(mockValue); |
| 108 | +``` |
| 109 | + |
| 110 | +## Common Test Cases for Hooks |
| 111 | + |
| 112 | +### 1. Basic Functionality |
| 113 | + |
| 114 | +```typescript |
| 115 | +it('should return expected value/function', () => { |
| 116 | + const { result } = renderHook(() => useYourHook()); |
| 117 | + expect(typeof result.current).toBe('function'); |
| 118 | +}); |
| 119 | +``` |
| 120 | + |
| 121 | +### 2. Dependency Calls |
| 122 | + |
| 123 | +```typescript |
| 124 | +it('should call dependencies with correct parameters', () => { |
| 125 | + const { result } = renderHook(() => useYourHook()); |
| 126 | + const hookFunction = result.current; |
| 127 | + |
| 128 | + hookFunction(mockInput); |
| 129 | + |
| 130 | + expect(mockedDependency).toHaveBeenCalledWith(expectedParams); |
| 131 | +}); |
| 132 | +``` |
| 133 | + |
| 134 | +### 3. Edge Cases |
| 135 | + |
| 136 | +```typescript |
| 137 | +it('should handle undefined/null inputs gracefully', () => { |
| 138 | + (mockedDependency as jest.Mock).mockReturnValue(undefined); |
| 139 | + |
| 140 | + const { result } = renderHook(() => useYourHook()); |
| 141 | + const hookFunction = result.current; |
| 142 | + |
| 143 | + expect(() => hookFunction(null)).not.toThrow(); |
| 144 | +}); |
| 145 | +``` |
| 146 | + |
| 147 | +### 4. Context Changes (useMemo behavior) |
| 148 | + |
| 149 | +```typescript |
| 150 | +it('should update when dependencies change', () => { |
| 151 | + const initialValue = { data: 'initial' }; |
| 152 | + const updatedValue = { data: 'updated' }; |
| 153 | + |
| 154 | + (useContext as jest.Mock).mockReturnValue(initialValue); |
| 155 | + |
| 156 | + const { result, rerender } = renderHook(() => useYourHook()); |
| 157 | + |
| 158 | + // Update context |
| 159 | + (useContext as jest.Mock).mockReturnValue(updatedValue); |
| 160 | + rerender(); |
| 161 | + |
| 162 | + // Test that hook uses updated value |
| 163 | + expect(result.current).toBeDefined(); |
| 164 | +}); |
| 165 | +``` |
| 166 | + |
| 167 | +## Model Type Utilities |
| 168 | + |
| 169 | +### Creating Mock Objects |
| 170 | + |
| 171 | +Create helper functions for complex model objects: |
| 172 | + |
| 173 | +```typescript |
| 174 | +const createMockRow = (overrides: Partial<ISheet> = {}): ISheet => ({ |
| 175 | + level: SheetLevel.Section, |
| 176 | + kind: IwsKind.Section, |
| 177 | + sectionSeq: 1, |
| 178 | + passageSeq: 0, |
| 179 | + passageType: PassageTypeEnum.PASSAGE, |
| 180 | + deleted: false, |
| 181 | + filtered: false, |
| 182 | + published: [], |
| 183 | + ...overrides, |
| 184 | +}); |
| 185 | +``` |
| 186 | + |
| 187 | +## Import Pattern Gotchas |
| 188 | + |
| 189 | +### 1. Import Order Matters |
| 190 | + |
| 191 | +- Always mock dependencies before importing the hook |
| 192 | +- Use `require()` for getting mock references after mocking |
| 193 | + |
| 194 | +### 2. Enum Usage |
| 195 | + |
| 196 | +- Import enums from their correct locations |
| 197 | +- Common enums: `PassageTypeEnum`, `SheetLevel`, `IwsKind` |
| 198 | +- `PublishDestinationEnum` comes from `../../crud`, not model |
| 199 | + |
| 200 | +### 3. Interface Requirements |
| 201 | + |
| 202 | +- `ISheet` requires `deleted`, `filtered`, and `published` properties |
| 203 | +- Use mock helper functions to ensure all required properties are present |
| 204 | + |
| 205 | +## Testing Environment |
| 206 | + |
| 207 | +### Jest Configuration |
| 208 | + |
| 209 | +- Tests run in `jsdom` environment |
| 210 | +- TypeScript configuration uses `tsconfig.jest.json` |
| 211 | +- Setup file: `jest.setup.ts` provides global test utilities |
| 212 | + |
| 213 | +### Running Tests |
| 214 | + |
| 215 | +```bash |
| 216 | +cd src/renderer |
| 217 | +npm test -- yourHookName.test.tsx |
| 218 | +``` |
| 219 | + |
| 220 | +## Common Errors and Solutions |
| 221 | + |
| 222 | +### "Cannot use import statement outside a module" |
| 223 | + |
| 224 | +- **Cause**: Complex dependency chain importing problematic modules |
| 225 | +- **Solution**: Mock all dependencies comprehensively, avoid real context providers |
| 226 | + |
| 227 | +### "Property does not exist on type" |
| 228 | + |
| 229 | +- **Cause**: Missing required properties on mock objects |
| 230 | +- **Solution**: Use helper functions that include all required properties |
| 231 | + |
| 232 | +### "Cannot access before initialization" |
| 233 | + |
| 234 | +- **Cause**: React reference in mock setup before import |
| 235 | +- **Solution**: Use `require()` syntax for mock references |
| 236 | + |
| 237 | +### Mock function not working |
| 238 | + |
| 239 | +- **Cause**: Mock setup after import, or incorrect mock pattern |
| 240 | +- **Solution**: Ensure mocks are set up before imports, use proper jest.Mock casting |
| 241 | + |
| 242 | +## Best Practices |
| 243 | + |
| 244 | +1. **Comprehensive Mocking**: Mock all external dependencies, don't try to use real ones |
| 245 | +2. **Helper Functions**: Create mock object builders for complex types |
| 246 | +3. **Clear Test Names**: Describe exactly what scenario is being tested |
| 247 | +4. **Edge Case Coverage**: Test null/undefined inputs and error conditions |
| 248 | +5. **Isolation**: Each test should be independent with proper cleanup |
| 249 | +6. **Documentation**: Add comments explaining complex mock setups |
| 250 | + |
| 251 | +## Example Template |
| 252 | + |
| 253 | +```typescript |
| 254 | +/** |
| 255 | + * Test suite for useExampleHook |
| 256 | + * |
| 257 | + * Brief description of what the hook does |
| 258 | + */ |
| 259 | + |
| 260 | +import { renderHook } from '@testing-library/react'; |
| 261 | +import React from 'react'; |
| 262 | + |
| 263 | +// Mock all dependencies first |
| 264 | +jest.mock('react', () => ({ |
| 265 | + ...jest.requireActual('react'), |
| 266 | + useContext: jest.fn(), |
| 267 | + useMemo: jest.fn(), |
| 268 | +})); |
| 269 | + |
| 270 | +jest.mock('../../context/useGlobal'); |
| 271 | +jest.mock('../../crud', () => ({ |
| 272 | + someFunction: jest.fn(), |
| 273 | +})); |
| 274 | + |
| 275 | +// Import hook after mocking |
| 276 | +import { useExampleHook } from './useExampleHook'; |
| 277 | +import { ISheet } from '../../model'; |
| 278 | + |
| 279 | +// Get mock references |
| 280 | +const { useContext, useMemo } = React; |
| 281 | +const { useGlobal } = require('../../context/useGlobal'); |
| 282 | +const { someFunction } = require('../../crud'); |
| 283 | + |
| 284 | +describe('useExampleHook', () => { |
| 285 | + const mockData = { |
| 286 | + /* mock setup */ |
| 287 | + }; |
| 288 | + |
| 289 | + const createMockInput = (overrides = {}): InputType => ({ |
| 290 | + // default properties |
| 291 | + ...overrides, |
| 292 | + }); |
| 293 | + |
| 294 | + beforeEach(() => { |
| 295 | + jest.clearAllMocks(); |
| 296 | + |
| 297 | + // Setup default mocks |
| 298 | + (useGlobal as jest.Mock).mockReturnValue([mockMemory, jest.fn()]); |
| 299 | + (useContext as jest.Mock).mockReturnValue(mockData); |
| 300 | + (useMemo as jest.Mock).mockImplementation((factory) => factory()); |
| 301 | + }); |
| 302 | + |
| 303 | + it('should handle basic functionality', () => { |
| 304 | + // Test implementation |
| 305 | + }); |
| 306 | + |
| 307 | + it('should handle edge cases', () => { |
| 308 | + // Test edge cases |
| 309 | + }); |
| 310 | +}); |
| 311 | +``` |
| 312 | + |
| 313 | +This pattern ensures reliable, isolated testing of hooks in this project's complex environment. |
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