Experimentally implement shared workers

ava.config.js

@@ -1,4 +1,9 @@
+const skipTests = [];
+if (process.versions.node < '12.16.0') {
+	skipTests.push('!test/shared-workers/!(requires-newish-node)/**');
+}
+
 export default {
-	files: ['test/**', '!test/**/{fixtures,helpers}/**'],
+	files: ['test/**', '!test/**/{fixtures,helpers}/**', ...skipTests],
 	ignoredByWatcher: ['{coverage,docs,media,test-d,test-tap}/**']
 };

lib/api.js

@@ -17,6 +17,7 @@ const RunStatus = require('./run-status');
 const fork = require('./fork');
 const serializeError = require('./serialize-error');
 const {getApplicableLineNumbers} = require('./line-numbers');
+const sharedWorkers = require('./shared-workers');
 
 function resolveModules(modules) {
 	return arrify(modules).map(name => {
@@ -231,6 +232,7 @@ class Api extends Emittery {
 
 				const worker = fork(file, options, apiOptions.nodeArguments);
 				runStatus.observeWorker(worker, file, {selectingLines: lineNumbers.length > 0});
+				sharedWorkers.observeWorkerProcess(worker, runStatus);
 
 				pendingWorkers.add(worker);
 				worker.promise.then(() => {

lib/fork.js

@@ -19,7 +19,55 @@ const serializeOptions = useAdvanced ?
 	options => JSON.parse(JSON.stringify(options)) : // Use JSON serialization to remove non-clonable values.
 	options => options;
 
+class SharedWorkerChannel extends Emittery {
+	constructor({channelId, filename, initialData}, sendToFork) {
+		super();
+
+		this.id = channelId;
+		this.filename = filename;
+		this.initialData = initialData;
+		this.sendToFork = sendToFork;
+	}
+
+	signalReady() {
+		this.sendToFork({
+			type: 'shared-worker-ready',
+			channelId: this.id
+		});
+	}
+
+	signalError() {
+		this.sendToFork({
+			type: 'shared-worker-error',
+			channelId: this.id
+		});
+	}
+
+	emitMessage({messageId, replyTo, data}) {
+		this.emit('message', {
+			messageId,
+			replyTo,
+			data
+		});
+	}
+
+	forwardMessageToFork({messageId, replyTo, data}) {
+		this.sendToFork({
+			type: 'shared-worker-message',
+			channelId: this.id,
+			messageId,
+			replyTo,
+			data
+		});
+	}
+}
+
+let forkCounter = 0;
+
 module.exports = (file, options, execArgv = process.execArgv) => {
+	const forkId = `fork/${++forkCounter}`;
+	const sharedWorkerChannels = new Map();
+
 	let finished = false;
 
 	const emitter = new Emittery();
@@ -32,6 +80,7 @@ module.exports = (file, options, execArgv = process.execArgv) => {
 	options = {
 		baseDir: process.cwd(),
 		file,
+		forkId,
 		...options
 	};
 
@@ -75,6 +124,16 @@ module.exports = (file, options, execArgv = process.execArgv) => {
 				case 'ready-for-options':
 					send({type: 'options', options: serializeOptions(options)});
 					break;
+				case 'shared-worker-connect': {
+					const channel = new SharedWorkerChannel(message.ava, send);
+					sharedWorkerChannels.set(channel.id, channel);
+					emitter.emit('connectSharedWorker', channel);
+					break;
+				}
+
+				case 'shared-worker-message':
+					sharedWorkerChannels.get(message.ava.channelId).emitMessage(message.ava);
+					break;
 				case 'ping':
 					send({type: 'pong'});
 					break;
@@ -105,6 +164,7 @@ module.exports = (file, options, execArgv = process.execArgv) => {
 
 	return {
 		file,
+		forkId,
 		promise,
 
 		exit() {
@@ -116,6 +176,10 @@ module.exports = (file, options, execArgv = process.execArgv) => {
 			send({type: 'peer-failed'});
 		},
 
+		onConnectSharedWorker(listener) {
+			return emitter.on('connectSharedWorker', listener);
+		},
+
 		onStateChange(listener) {
 			return emitter.on('stateChange', listener);
 		}

lib/load-config.js

@@ -7,7 +7,7 @@ const pkgConf = require('pkg-conf');
 
 const NO_SUCH_FILE = Symbol('no ava.config.js file');
 const MISSING_DEFAULT_EXPORT = Symbol('missing default export');
-const EXPERIMENTS = new Set();
+const EXPERIMENTS = new Set(['sharedWorkers']);
 
 // *Very* rudimentary support for loading ava.config.js files containing an `export default` statement.
 const evaluateJsConfig = configFile => {

lib/reporters/mini.js

@@ -117,6 +117,7 @@ class MiniReporter {
 		this.prefixTitle = (testFile, title) => title;
 		this.previousFailures = 0;
 		this.removePreviousListener = null;
+		this.sharedWorkerErrors = [];
 		this.stats = null;
 		this.uncaughtExceptions = [];
 		this.unhandledRejections = [];
@@ -180,6 +181,9 @@ class MiniReporter {
 			case 'selected-test':
 				// Ignore
 				break;
+			case 'shared-worker-error':
+				this.sharedWorkerErrors.push(evt);
+				break;
 			case 'stats':
 				this.stats = evt.stats;
 				break;
@@ -511,7 +515,7 @@ class MiniReporter {
 		const shouldWriteFailFastDisclaimer = this.failFastEnabled && (this.stats.remainingTests > 0 || this.stats.files > this.stats.finishedWorkers);
 
 		if (this.failures.length > 0) {
-			const writeTrailingLines = shouldWriteFailFastDisclaimer || this.internalErrors.length > 0 || this.uncaughtExceptions.length > 0 || this.unhandledRejections.length > 0;
+			const writeTrailingLines = shouldWriteFailFastDisclaimer || this.internalErrors.length > 0 || this.sharedWorkerErrors.length > 0 || this.uncaughtExceptions.length > 0 || this.unhandledRejections.length > 0;
 			this.lineWriter.writeLine();
 
 			const last = this.failures[this.failures.length - 1];
@@ -527,7 +531,7 @@ class MiniReporter {
 
 		if (this.internalErrors.length > 0) {
 			const writeLeadingLine = this.failures.length === 0;
-			const writeTrailingLines = shouldWriteFailFastDisclaimer || this.uncaughtExceptions.length > 0 || this.unhandledRejections.length > 0;
+			const writeTrailingLines = shouldWriteFailFastDisclaimer || this.sharedWorkerErrors.length > 0 || this.uncaughtExceptions.length > 0 || this.unhandledRejections.length > 0;
 
 			if (writeLeadingLine) {
 				this.lineWriter.writeLine();
@@ -551,8 +555,30 @@ class MiniReporter {
 			}
 		}
 
-		if (this.uncaughtExceptions.length > 0) {
+		if (this.sharedWorkerErrors.length > 0) {
 			const writeLeadingLine = this.failures.length === 0 && this.internalErrors.length === 0;
+			const writeTrailingLines = shouldWriteFailFastDisclaimer || this.uncaughtExceptions.length > 0 || this.unhandledRejections.length > 0;
+
+			if (writeLeadingLine) {
+				this.lineWriter.writeLine();
+			}
+
+			const last = this.sharedWorkerErrors[this.sharedWorkerErrors.length - 1];
+			for (const evt of this.sharedWorkerErrors) {
+				this.lineWriter.writeLine(colors.error(`${figures.cross} Error in shared worker`));
+
+				this.lineWriter.writeLine(colors.stack(evt.err.summary));
+				this.lineWriter.writeLine(colors.errorStack(evt.err.stack));
+				if (evt !== last || writeTrailingLines) {
+					this.lineWriter.writeLine();
+					this.lineWriter.writeLine();
+					this.lineWriter.writeLine();
+				}
+			}
+		}
+
+		if (this.uncaughtExceptions.length > 0) {
+			const writeLeadingLine = this.failures.length === 0 && this.internalErrors.length === 0 && this.sharedWorkerErrors.length === 0;
 			const writeTrailingLines = shouldWriteFailFastDisclaimer || this.unhandledRejections.length > 0;
 
 			if (writeLeadingLine) {
@@ -573,7 +599,7 @@ class MiniReporter {
 		}
 
 		if (this.unhandledRejections.length > 0) {
-			const writeLeadingLine = this.failures.length === 0 && this.internalErrors.length === 0 && this.uncaughtExceptions.length === 0;
+			const writeLeadingLine = this.failures.length === 0 && this.internalErrors.length === 0 && this.sharedWorkerErrors.length === 0 && this.uncaughtExceptions.length === 0;
 			const writeTrailingLines = shouldWriteFailFastDisclaimer;
 
 			if (writeLeadingLine) {

lib/reporters/verbose.js

@@ -150,6 +150,14 @@ class VerboseReporter {
 					this.lineWriter.writeLine(colors.todo(`- ${this.prefixTitle(evt.testFile, evt.title)}`));
 				}
 
+				break;
+			case 'shared-worker-error':
+				this.lineWriter.writeLine(colors.error(`${figures.cross} Error in shared worker`));
+
+				this.lineWriter.writeLine(colors.stack(evt.err.summary));
+				this.lineWriter.writeLine(colors.errorStack(evt.err.stack));
+				this.lineWriter.writeLine();
+				this.lineWriter.writeLine();
 				break;
 			case 'stats':
 				this.stats = evt.stats;

lib/runner.js

@@ -41,6 +41,7 @@ class Runner extends Emittery {
 			serial: [],
 			todo: []
 		};
+		this.waitForReady = [];
 
 		const uniqueTestTitles = new Set();
 		this.registerUniqueTitle = title => {
@@ -435,6 +436,8 @@ class Runner extends Emittery {
 			});
 		}
 
+		await Promise.all(this.waitForReady);
+
 		if (concurrentTests.length === 0 && serialTests.length === 0) {
 			this.emit('finish');
 			// Don't run any hooks if there are no tests to run.