Rewrite watcher

Author: novemberborn

docs/recipes/watch-mode.md

@@ -14,9 +14,9 @@ $ npx ava --watch
 
 Please note that integrated debugging and the TAP reporter are unavailable when using watch mode.
 
-## Requirements
+## Limitations
 
-AVA uses [`chokidar`] as the file watcher. Note that even if you see warnings about optional dependencies failing during install, it will still work fine. Please refer to the *[Install Troubleshooting]* section of `chokidar` documentation for how to resolve the installation problems with chokidar.
+AVA uses `fs.watch()`. On supported platforms, `recursive` mode is used. When not supported, `fs.watch()` is used with individual directories, based on the dependency tracking (see below). This is an approximation. `recursive` mode is available with Node.js 19.1 on Linux, MacOS and Windows so we will not attempt to improve our fallback implementation.
 
 ## Ignoring changes
 
@@ -30,7 +30,7 @@ If your tests write to disk they may trigger the watcher to rerun your tests. Co
 
 AVA tracks which source files your test files depend on. If you change such a dependency only the test file that depends on it will be rerun. AVA will rerun all tests if it cannot determine which test file depends on the changed source file.
 
-Dependency tracking works for required modules. Custom extensions and transpilers are supported, provided you [added them in your `package.json` or `ava.config.*` file][config], and not from inside your test file. Files accessed using the `fs` module are not tracked.
+Dependency tracking works for `require()` and `import` syntax, as supported by [@vercel/nft](https://github.com/vercel/nft). `import()` is supported but dynamic paths such as `import(myVariable)` are not. Files accessed using the `fs` module are not tracked.
 
 ## Watch mode and the `.only` modifier
 
@@ -60,8 +60,6 @@ $ DEBUG=ava:watcher npx ava --watch
 
 Watch mode is relatively new and there might be some rough edges. Please [report](https://github.com/avajs/ava/issues) any issues you encounter. Thanks!
 
-[`chokidar`]: https://github.com/paulmillr/chokidar
-[Install Troubleshooting]: https://github.com/paulmillr/chokidar#install-troubleshooting
 [`ignore-by-default`]: https://github.com/novemberborn/ignore-by-default
 [`.only` modifier]: ../01-writing-tests.md#running-specific-tests
 [config]: ../06-configuration.md

lib/api.js

@@ -200,15 +200,14 @@ export default class Api extends Emittery {
 
 			await this.emit('run', {
 				bailWithoutReporting: debugWithoutSpecificFile,
-				clearLogOnNextRun: runtimeOptions.clearLogOnNextRun === true,
 				debug: Boolean(this.options.debug),
 				failFastEnabled: failFast,
 				filePathPrefix: getFilePathPrefix(selectedFiles),
 				files: selectedFiles,
 				matching: apiOptions.match.length > 0,
 				previousFailures: runtimeOptions.previousFailures || 0,
 				runOnlyExclusive: runtimeOptions.runOnlyExclusive === true,
-				runVector: runtimeOptions.runVector || 0,
+				firstRun: runtimeOptions.firstRun ?? true,
 				status: runStatus,
 			});
 
@@ -306,7 +305,8 @@ export default class Api extends Emittery {
 
 			// Allow shared workers to clean up before the run ends.
 			await Promise.all(deregisteredSharedWorkers);
-			scheduler.storeFailedTestFiles(runStatus, this.options.cacheEnabled === false ? null : this._createCacheDir());
+			const files = scheduler.storeFailedTestFiles(runStatus, this.options.cacheEnabled === false ? null : this._createCacheDir());
+			runStatus.emitStateChange({type: 'touched-files', files});
 		} catch (error) {
 			if (error && error.name === 'AggregateError') {
 				for (const error_ of error.errors) {

lib/cli.js

@@ -25,7 +25,7 @@ import pkg from './pkg.cjs';
 import providerManager from './provider-manager.js';
 import DefaultReporter from './reporters/default.js';
 import TapReporter from './reporters/tap.js';
-import Watcher from './watcher.js';
+import {start as startWatcher} from './watcher.js';
 
 function exit(message) {
 	console.error(`\n  ${chalk.red(figures.cross)} ${message}`);
@@ -469,15 +469,15 @@ export default async function loadCli() { // eslint-disable-line complexity
 	});
 
 	if (combined.watch) {
-		const watcher = new Watcher({
+		startWatcher({
 			api,
 			filter,
 			globs,
 			projectDir,
 			providers,
 			reporter,
+			stdin: process.stdin,
 		});
-		watcher.observeStdin(process.stdin);
 	} else {
 		let debugWithoutSpecificFile = false;
 		api.on('run', plan => {

lib/glob-helpers.cjs

@@ -15,8 +15,6 @@ const defaultPicomatchIgnorePatterns = [
 	...defaultIgnorePatterns.map(pattern => `${pattern}/**/*`),
 ];
 
-const defaultMatchNoIgnore = picomatch(defaultPicomatchIgnorePatterns);
-
 const matchingCache = new WeakMap();
 const processMatchingPatterns = input => {
 	let result = matchingCache.get(input);
@@ -45,15 +43,9 @@ const processMatchingPatterns = input => {
 
 exports.processMatchingPatterns = processMatchingPatterns;
 
-const matchesIgnorePatterns = (file, patterns) => {
-	const {matchNoIgnore} = processMatchingPatterns(patterns);
-	return matchNoIgnore(file) || defaultMatchNoIgnore(file);
-};
-
-function classify(file, {cwd, extensions, filePatterns, ignoredByWatcherPatterns}) {
+function classify(file, {cwd, extensions, filePatterns}) {
 	file = normalizeFileForMatching(cwd, file);
 	return {
-		isIgnoredByWatcher: matchesIgnorePatterns(file, ignoredByWatcherPatterns),
 		isTest: hasExtension(extensions, file) && !isHelperish(file) && filePatterns.length > 0 && matches(file, filePatterns),
 	};
 }

lib/globs.js

@@ -2,6 +2,7 @@ import fs from 'node:fs';
 import path from 'node:path';
 
 import {globby, globbySync} from 'globby';
+import picomatch from 'picomatch';
 
 import {
 	defaultIgnorePatterns,
@@ -126,11 +127,13 @@ export async function findTests({cwd, extensions, filePatterns}) {
 	return files.filter(file => !path.basename(file).startsWith('_'));
 }
 
-export function getChokidarIgnorePatterns({ignoredByWatcherPatterns}) {
-	return [
+export function buildIgnoreMatcher({ignoredByWatcherPatterns}) {
+	const patterns = [
 		...defaultIgnorePatterns.map(pattern => `${pattern}/**/*`),
 		...ignoredByWatcherPatterns.filter(pattern => !pattern.startsWith('!')),
 	];
+
+	return picomatch(patterns, {dot: true});
 }
 
 export function applyTestFileFilter({ // eslint-disable-line complexity

lib/reporters/default.js

@@ -148,7 +148,7 @@ export default class Reporter {
 			this.consumeStateChange(evt);
 		});
 
-		if (this.watching && plan.runVector > 1) {
+		if (this.watching && !plan.firstRun) {
 			this.lineWriter.write(chalk.gray.dim('\u2500'.repeat(this.lineWriter.columns)) + os.EOL);
 		}
 

lib/scheduler.js

@@ -13,9 +13,22 @@ const scheduler = {
 			return;
 		}
 
+		const filename = path.join(cacheDir, FILENAME);
+		// Given that we're writing to a cache directory, consider this file
+		// temporary.
+		const temporaryFiles = [filename];
 		try {
-			writeFileAtomic.sync(path.join(cacheDir, FILENAME), JSON.stringify(runStatus.getFailedTestFiles()));
+			writeFileAtomic.sync(filename, JSON.stringify(runStatus.getFailedTestFiles()), {
+				tmpfileCreated(tmpfile) {
+					temporaryFiles.push(tmpfile);
+				},
+			});
 		} catch {}
+
+		return {
+			changedFiles: [],
+			temporaryFiles,
+		};
 	},
 
 	// Order test-files, so that files with failing tests come first