0
# Watch Plugin
1

2
Interactive Jest watch plugin that allows toggling ESLint's --fix option during development without restarting the watch process.
3

4
## Capabilities
5

6
### ESLintWatchFixPlugin Class
7

8
Jest watch plugin class that provides interactive --fix option toggling.
9

10
```javascript { .api }
11
/**
12
 * Jest watch plugin for toggling ESLint --fix option during watch mode
13
 * Requires Jest 23.0.0 or higher
14
 */
15
class ESLintWatchFixPlugin {
16
  /**
17
   * Creates new watch plugin instance
18
   * @param options - Plugin initialization options
19
   */
20
  constructor(options: WatchPluginOptions);
21
  
22
  /**
23
   * Executes when plugin key is pressed - toggles fix option
24
   * @returns Promise<boolean> - Always returns true to continue watch mode
25
   */
26
  async run(): Promise<boolean>;
27
  
28
  /**
29
   * Provides usage information for Jest watch mode display
30
   * @returns Object with key and prompt for watch mode menu
31
   */
32
  getUsageInfo(): WatchPluginUsageInfo;
33
}
34

35
interface WatchPluginOptions {
36
  /** Output stream for plugin messages */
37
  stdout: NodeJS.WriteStream;
38
  /** Plugin configuration */
39
  config: {
40
    /** Key to press for activating plugin (default: 'F') */
41
    key?: string;
42
  };
43
}
44

45
interface WatchPluginUsageInfo {
46
  /** Key to display in watch mode menu */
47
  key: string;
48
  /** Description text for watch mode menu */
49
  prompt: string;
50
}
51
```
52

53
**Usage Examples:**
54

55
```javascript
56
// jest.config.js - Adding watch plugin
57
module.exports = {
58
  projects: [
59
    {
60
      runner: 'jest-runner-eslint',
61
      displayName: 'lint',
62
      testMatch: ['<rootDir>/src/**/*.js'],
63
    },
64
  ],
65
  watchPlugins: [
66
    'jest-runner-eslint/watch-fix',
67
  ],
68
};
69

70
// Custom key configuration
71
module.exports = {
72
  watchPlugins: [
73
    ['jest-runner-eslint/watch-fix', { key: 'L' }],
74
  ],
75
};
76
```
77

78
### Watch Plugin Entry Point
79

80
Module export for the watch plugin functionality.
81

82
```javascript { .api }
83
/**
84
 * Watch plugin module export
85
 * Re-exports ESLintWatchFixPlugin from build directory
86
 */
87
const ESLintWatchFixPlugin = require("jest-runner-eslint/watch-fix");
88
```
89

90
**Usage Examples:**
91

92
```javascript
93
// Direct instantiation (not typically needed)
94
const ESLintWatchFixPlugin = require("jest-runner-eslint/watch-fix");
95

96
const plugin = new ESLintWatchFixPlugin({
97
  stdout: process.stdout,
98
  config: { key: 'F' }
99
});
100

101
// Get current usage info
102
const usageInfo = plugin.getUsageInfo();
103
console.log(`Press ${usageInfo.key} to ${usageInfo.prompt}`);
104

105
// Toggle fix option
106
await plugin.run();
107
```
108

109
### Configuration Override System
110

111
Internal system for managing fix option overrides during watch mode.
112

113
```javascript { .api }
114
/**
115
 * Configuration override manager for watch mode fix option
116
 * Singleton instance that manages global fix state
117
 */
118
class ConfigOverrides {
119
  /**
120
   * Sets the fix option override value
121
   * @param fix - Boolean value to set as fix override
122
   */
123
  setFix(fix: boolean): void;
124
  
125
  /**
126
   * Gets the current fix option override value
127
   * @returns Current fix override value or undefined if not set
128
   */
129
  getFix(): boolean | undefined;
130
}
131

132
/** Singleton instance of ConfigOverrides */
133
const configOverrides: ConfigOverrides;
134
```
135

136
**Usage Examples:**
137

138
```javascript
139
// Internal usage by watch plugin
140
const configOverrides = require('./utils/configOverrides');
141

142
// Toggle current fix state
143
const currentFix = configOverrides.getFix();
144
configOverrides.setFix(!currentFix);
145

146
// Check fix state in runner
147
const fixOverride = configOverrides.getFix();
148
const shouldFix = fixOverride !== undefined ? fixOverride : baseConfig.fix;
149
```
150

151
### Watch Mode Integration
152

153
The watch plugin integrates with Jest's watch mode system to provide interactive ESLint configuration.
154

155
**Key Features:**
156

157
- **Dynamic Fix Toggle**: Toggle --fix option without restarting Jest watch mode
158
- **Visual Feedback**: Shows current fix state in watch mode prompt
159
- **Persistent State**: Fix override persists throughout watch session
160
- **Configurable Key**: Customize the key used to trigger the plugin (default: 'F')
161

162
**Watch Mode Display:**
163

164
```text
165
Watch Usage
166
 › Press f to run only failed tests.
167
 › Press o to only run tests related to changed files.
168
 › Press F to toggle ESLint --fix (disabled).
169
 › Press q to quit watch mode.
170
```
171

172
The prompt text updates based on current fix state:
173
- `"override ESLint --fix"` - When no override is set
174
- `"toggle ESLint --fix (disabled)"` - When fix is explicitly disabled
175
- `"toggle ESLint --fix (enabled)"` - When fix is explicitly enabled