Test: Cover failure branches of QUnit.on

Gruntfile.js

@@ -128,6 +128,7 @@ module.exports = function (grunt) {
         'test/main/diff.js',
         'test/main/dump.js',
         'test/main/each.js',
+        'test/main/events.js',
         'test/main/HtmlReporter.js',
         'test/main/modules.js',
         'test/main/modules-es2018.js',

src/events.js

@@ -28,6 +28,7 @@ const MEMORY_EVENTS = [
  * @return {void}
  */
 export function emit (eventName, data) {
+  /* istanbul ignore if: private function */
   if (typeof eventName !== 'string') {
     throw new TypeError('eventName must be a string when emitting an event');
   }

test/index-es5.html

@@ -20,6 +20,7 @@
   <script src="main/diff.js"></script>
   <script src="main/dump.js"></script>
   <script src="main/each.js"></script>
+  <script src="main/events.js"></script>
   <script src="main/HtmlReporter.js"></script>
   <script src="main/legacy.js"></script>
   <script src="main/modules.js"></script>

test/index-xhtml.xhtml

@@ -32,6 +32,7 @@
   <script src="main/diff.js"></script>
   <script src="main/dump.js"></script>
   <script src="main/each.js"></script>
+  <script src="main/events.js"></script>
   <script src="main/HtmlReporter.js"></script>
   <script src="main/legacy.js"></script>
   <script src="main/modules-es2018.js"></script>

test/index.html

@@ -20,6 +20,7 @@
   <script src="main/diff.js"></script>
   <script src="main/dump.js"></script>
   <script src="main/each.js"></script>
+  <script src="main/events.js"></script>
   <script src="main/HtmlReporter.js"></script>
   <script src="main/legacy.js"></script>
   <script src="main/modules-es2018.js"></script>

test/main/assert-step.js

@@ -116,6 +116,10 @@ QUnit.module('assert.step', function () {
     assert.verifySteps(['two']);
   });
 
+  QUnit.test('empty verifySteps()', function (assert) {
+    assert.verifySteps([]);
+  });
+
   QUnit.test('errors if not called when `assert.step` is used', function (assert) {
     assert.expect(2);
     assert.step('one');

test/main/events.js

@@ -0,0 +1,25 @@
+QUnit.module('events', function () {
+  QUnit.test('QUnit.on [failure]', function (assert) {
+    assert.throws(function () {
+      QUnit.on(null, function () {
+        assert.step('null called');
+      });
+    }, /must be a string/, 'null event name');
+
+    assert.throws(function () {
+      QUnit.on('banana', function () {
+        assert.step('banana called');
+      });
+    }, /not a valid event/, 'unknown event name');
+
+    assert.throws(function () {
+      QUnit.on('runStart');
+    }, /must be a function/, 'missing callback');
+
+    assert.throws(function () {
+      QUnit.on('runStart', null);
+    }, /must be a function/, 'null callback');
+
+    assert.verifySteps([]);
+  });
+});

test/mozjs.js

@@ -22,6 +22,7 @@ loadRelativeToScript('../test/main/deepEqual.js');
 loadRelativeToScript('../test/main/diff.js');
 loadRelativeToScript('../test/main/dump.js');
 loadRelativeToScript('../test/main/each.js');
+loadRelativeToScript('../test/main/events.js');
 loadRelativeToScript('../test/main/HtmlReporter.js');
 // loadRelativeToScript( "../test/main/modules.js" ); // Requires setTimeout
 loadRelativeToScript('../test/main/modules-es2018.js');

test/mozjs.mjs

@@ -11,6 +11,7 @@ import '../test/main/deepEqual.js';
 import '../test/main/diff.js';
 import '../test/main/dump.js';
 import '../test/main/each.js';
+import '../test/main/events.js';
 import '../test/main/HtmlReporter.js';
 // import  "../test/main/modules.js"; // Requires setTimeout
 import '../test/main/modules-es2018.js';

test/webWorker-worker.js

@@ -16,6 +16,7 @@ importScripts(
   'main/diff.js',
   'main/dump.js',
   'main/each.js',
+  'main/events.js',
   'main/HtmlReporter.js',
   'main/modules.js',
   'main/modules-es2018.js',