test: add basic tests for worker

test/parallel/test-worker-uncaught-exception-async.js

@@ -0,0 +1,17 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { Worker } = require('worker');
+
+if (process.isMainThread) {
+  const w = new Worker(__filename);
+  w.on('message', common.mustNotCall());
+  w.on('error', common.mustCall((err) => {
+    // TODO(addaleax): be more specific here
+    assert(/foo/.test(err));
+  }));
+} else {
+  setImmediate(() => {
+    throw new Error('foo');
+  });
+}

test/parallel/test-worker-uncaught-exception.js

@@ -0,0 +1,15 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { Worker } = require('worker');
+
+if (process.isMainThread) {
+  const w = new Worker(__filename);
+  w.on('message', common.mustNotCall());
+  w.on('error', common.mustCall((err) => {
+    // TODO(addaleax): be more specific here
+    assert(/foo/.test(err));
+  }));
+} else {
+  throw new Error('foo');
+}

test/parallel/test-worker.js

@@ -0,0 +1,17 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { Worker } = require('worker');
+
+if (process.isMainThread) {
+  const w = new Worker(__filename);
+  w.on('message', common.mustCall((message) => {
+    assert.strictEqual(message, 'Hello, world!');
+  }));
+} else {
+  setImmediate(() => {
+    process.nextTick(() => {
+      process.postMessage('Hello, world!');
+    });
+  });
+}