test: improve coverage of lib/events.js

test/parallel/test-event-emitter-emit-context.js

@@ -0,0 +1,18 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const EventEmitter = require('events');
+
+// Test emit called by other context
+const EE = new EventEmitter();
+
+// Works as expected if the context has no `constructor.name`
+{
+  const ctx = Object.create(null);
+  assert.throws(
+    () => EE.emit.call(ctx, 'error', new Error('foo')),
+    common.expectsError({ name: 'Error', message: 'foo' })
+  );
+}
+
+assert.strictEqual(EE.emit.call({}, 'foo'), false);

test/parallel/test-event-on-async-iterator.js → test/parallel/test-events-on-async-iterator.js

@@ -35,6 +35,13 @@ async function basic() {
   assert.strictEqual(ee.listenerCount('error'), 0);
 }
 
+async function invalidArgType() {
+  assert.throws(() => on({}, 'foo'), common.expectsError({
+    code: 'ERR_INVALID_ARG_TYPE',
+    name: 'TypeError',
+  }));
+}
+
 async function error() {
   const ee = new EventEmitter();
   const _err = new Error('kaboom');
@@ -359,6 +366,7 @@ async function abortableOnAfterDone() {
 async function run() {
   const funcs = [
     basic,
+    invalidArgType,
     error,
     errorDelayed,
     throwInLoop,