feat(mock-doc): dispatch blur and focus events (#3449)

for mock-doc, `blur()` and `focus()` methods will now dispatch an
event. created `MockFocusEvent` which extends a new 
`MockUIEvent`, which extends the existing `MockEvent`.

src/mock-doc/event.ts

@@ -1,6 +1,7 @@
 import { MockDocument } from './document';
 import { MockElement } from './node';
 import { NODE_NAMES } from './constants';
+import { MockWindow } from './window';
 
 export class MockEvent {
   bubbles = false;
@@ -113,6 +114,31 @@ export class MockMouseEvent extends MockEvent {
   }
 }
 
+export class MockUIEvent extends MockEvent {
+  detail: number | null = null;
+  view: MockWindow | null = null;
+
+  constructor(type: string, uiEventInitDic?: UIEventInit) {
+    super(type);
+
+    if (uiEventInitDic != null) {
+      Object.assign(this, uiEventInitDic);
+    }
+  }
+}
+
+export class MockFocusEvent extends MockUIEvent {
+  relatedTarget: EventTarget | null = null;
+
+  constructor(type: 'blur' | 'focus', focusEventInitDic?: FocusEventInit) {
+    super(type);
+
+    if (focusEventInitDic != null) {
+      Object.assign(this, focusEventInitDic);
+    }
+  }
+}
+
 export class MockEventListener {
   type: string;
   handler: (ev?: any) => void;

src/mock-doc/global.ts

@@ -13,7 +13,7 @@ import {
   MockTemplateElement,
   MockTitleElement,
 } from './element';
-import { MockCustomEvent, MockEvent, MockKeyboardEvent, MockMouseEvent } from './event';
+import { MockCustomEvent, MockEvent, MockFocusEvent, MockKeyboardEvent, MockMouseEvent } from './event';
 import { MockHeaders } from './headers';
 import { MockRequest, MockResponse } from './request-response';
 import { MockDOMParser } from './parser';
@@ -148,6 +148,7 @@ const WINDOW_PROPS = [
   'HTMLElement',
   'Node',
   'NodeList',
+  'FocusEvent',
   'KeyboardEvent',
   'MouseEvent',
 ];
@@ -156,6 +157,7 @@ const GLOBAL_CONSTRUCTORS: [string, any][] = [
   ['CustomEvent', MockCustomEvent],
   ['Event', MockEvent],
   ['Headers', MockHeaders],
+  ['FocusEvent', MockFocusEvent],
   ['KeyboardEvent', MockKeyboardEvent],
   ['MouseEvent', MockMouseEvent],
   ['Request', MockRequest],

src/mock-doc/node.ts

@@ -4,7 +4,14 @@ import { matches, selectAll, selectOne } from './selector';
 import { MockAttr, MockAttributeMap, createAttributeProxy } from './attribute';
 import { MockClassList } from './class-list';
 import { MockCSSStyleDeclaration, createCSSStyleDeclaration } from './css-style-declaration';
-import { MockEvent, addEventListener, dispatchEvent, removeEventListener, resetEventListeners } from './event';
+import {
+  MockEvent,
+  addEventListener,
+  dispatchEvent,
+  removeEventListener,
+  resetEventListeners,
+  MockFocusEvent,
+} from './event';
 import { NODE_NAMES, NODE_TYPES } from './constants';
 import { NON_ESCAPABLE_CONTENT, SerializeNodeToHtmlOptions, serializeNodeToHtml } from './serialize-node';
 import { parseFragmentUtil } from './parse-util';
@@ -236,7 +243,10 @@ export class MockElement extends MockNode {
   }
 
   blur() {
-    /**/
+    dispatchEvent(
+      this,
+      new MockFocusEvent('blur', { relatedTarget: null, bubbles: true, cancelable: true, composed: true })
+    );
   }
 
   get shadowRoot() {
@@ -320,7 +330,12 @@ export class MockElement extends MockNode {
     return this.children[0] || null;
   }
 
-  focus(_options?: { preventScroll?: boolean }) {}
+  focus(_options?: { preventScroll?: boolean }) {
+    dispatchEvent(
+      this,
+      new MockFocusEvent('focus', { relatedTarget: null, bubbles: true, cancelable: true, composed: true })
+    );
+  }
 
   getAttribute(attrName: string) {
     if (attrName === 'style') {

src/mock-doc/test/event.spec.ts

@@ -90,6 +90,49 @@ describe('event', () => {
     expect(ev.detail).toBe(88);
   });
 
+  it('FocusEvent() requires type', () => {
+    expect(() => {
+      // @ts-ignore checking that it throws when not supplied required arguments
+      new win.FocusEvent();
+    }).toThrow();
+  });
+
+  const focusEventTypes: ('blur' | 'focus')[] = ['blur', 'focus'];
+  it.each(focusEventTypes)('creates a %s-type MockFocusEvent', (focusType) => {
+    const ev = new win.FocusEvent(focusType);
+    expect(ev.bubbles).toBe(false);
+    expect(ev.cancelBubble).toBe(false);
+    expect(ev.cancelable).toBe(false);
+    expect(ev.composed).toBe(false);
+    expect(ev.currentTarget).toBe(null);
+    expect(ev.defaultPrevented).toBe(false);
+    expect(ev.srcElement).toBe(null);
+    expect(ev.target).toBe(null);
+    expect(typeof ev.timeStamp).toBe('number');
+    expect(ev.type).toBe(focusType);
+    expect(ev.relatedTarget).toBe(null);
+  });
+
+  it('FocusEvent(type, focusEventInitDic)', () => {
+    const focusEventInitDic = {
+      bubbles: true,
+      composed: true,
+      relatedTarget: null as EventTarget | null,
+    };
+    const ev = new win.FocusEvent('blur', focusEventInitDic);
+    expect(ev.bubbles).toBe(true);
+    expect(ev.cancelBubble).toBe(false);
+    expect(ev.cancelable).toBe(false);
+    expect(ev.composed).toBe(true);
+    expect(ev.currentTarget).toBe(null);
+    expect(ev.defaultPrevented).toBe(false);
+    expect(ev.srcElement).toBe(null);
+    expect(ev.target).toBe(null);
+    expect(typeof ev.timeStamp).toBe('number');
+    expect(ev.type).toBe('blur');
+    expect(ev.relatedTarget).toBe(null);
+  });
+
   it('KeyboardEvent() requires type', () => {
     expect(() => {
       // @ts-ignore checking that it throws when not supplied required arguments

src/mock-doc/window.ts

@@ -10,6 +10,7 @@ import {
   MockMouseEvent,
   MockCustomEvent,
   MockKeyboardEvent,
+  MockFocusEvent,
 } from './event';
 import { MockDocument, resetDocument } from './document';
 import { MockDocumentFragment } from './document-fragment';
@@ -74,6 +75,7 @@ export class MockWindow {
   CustomEvent: typeof MockCustomEvent;
   Event: typeof MockEvent;
   Headers: typeof MockHeaders;
+  FocusEvent: typeof MockFocusEvent;
   KeyboardEvent: typeof MockKeyboardEvent;
   MouseEvent: typeof MockMouseEvent;