Watch Plugin

/**
 * Jest watch plugin for toggling ESLint --fix option during watch mode
 * Requires Jest 23.0.0 or higher
 */
class ESLintWatchFixPlugin {
  /**
   * Creates new watch plugin instance
   * @param options - Plugin initialization options
   */
  constructor(options: WatchPluginOptions);
  
  /**
   * Executes when plugin key is pressed - toggles fix option
   * @returns Promise<boolean> - Always returns true to continue watch mode
   */
  async run(): Promise<boolean>;
  
  /**
   * Provides usage information for Jest watch mode display
   * @returns Object with key and prompt for watch mode menu
   */
  getUsageInfo(): WatchPluginUsageInfo;
}

interface WatchPluginOptions {
  /** Output stream for plugin messages */
  stdout: NodeJS.WriteStream;
  /** Plugin configuration */
  config: {
    /** Key to press for activating plugin (default: 'F') */
    key?: string;
  };
}

interface WatchPluginUsageInfo {
  /** Key to display in watch mode menu */
  key: string;
  /** Description text for watch mode menu */
  prompt: string;
}

// jest.config.js - Adding watch plugin
module.exports = {
  projects: [
    {
      runner: 'jest-runner-eslint',
      displayName: 'lint',
      testMatch: ['<rootDir>/src/**/*.js'],
    },
  ],
  watchPlugins: [
    'jest-runner-eslint/watch-fix',
  ],
};

// Custom key configuration
module.exports = {
  watchPlugins: [
    ['jest-runner-eslint/watch-fix', { key: 'L' }],
  ],
};

/**
 * Watch plugin module export
 * Re-exports ESLintWatchFixPlugin from build directory
 */
const ESLintWatchFixPlugin = require("jest-runner-eslint/watch-fix");

// Direct instantiation (not typically needed)
const ESLintWatchFixPlugin = require("jest-runner-eslint/watch-fix");

const plugin = new ESLintWatchFixPlugin({
  stdout: process.stdout,
  config: { key: 'F' }
});

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

// Toggle fix option
await plugin.run();

/**
 * Configuration override manager for watch mode fix option
 * Singleton instance that manages global fix state
 */
class ConfigOverrides {
  /**
   * Sets the fix option override value
   * @param fix - Boolean value to set as fix override
   */
  setFix(fix: boolean): void;
  
  /**
   * Gets the current fix option override value
   * @returns Current fix override value or undefined if not set
   */
  getFix(): boolean | undefined;
}

/** Singleton instance of ConfigOverrides */
const configOverrides: ConfigOverrides;

// Internal usage by watch plugin
const configOverrides = require('./utils/configOverrides');

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

// Check fix state in runner
const fixOverride = configOverrides.getFix();
const shouldFix = fixOverride !== undefined ? fixOverride : baseConfig.fix;

Watch Usage
 › Press f to run only failed tests.
 › Press o to only run tests related to changed files.
 › Press F to toggle ESLint --fix (disabled).
 › Press q to quit watch mode.