Check leaks in Mocha

.mocharc.json

@@ -0,0 +1,3 @@
+{
+  "checkLeaks": true
+}

ts/test-electron/quill/emoji/completion_test.tsx

@@ -7,9 +7,6 @@ import sinon from 'sinon';
 import { EmojiCompletion } from '../../../quill/emoji/completion';
 import { EmojiData } from '../../../components/emoji/lib';
 
-// eslint-disable-next-line @typescript-eslint/no-explicit-any
-const globalAsAny = global as any;
-
 describe('emojiCompletion', () => {
   let emojiCompletion: EmojiCompletion;
   const mockOnPickEmoji = sinon.spy();
@@ -18,14 +15,6 @@ describe('emojiCompletion', () => {
   let mockQuill: any;
 
   beforeEach(function beforeEach() {
-    this.oldDocument = globalAsAny.document;
-    globalAsAny.document = {
-      body: {
-        appendChild: () => null,
-      },
-      createElement: () => null,
-    };
-
     mockQuill = {
       getLeaf: sinon.stub(),
       getSelection: sinon.stub(),
@@ -55,12 +44,6 @@ describe('emojiCompletion', () => {
     mockOnPickEmoji.resetHistory();
     mockSetEmojiPickerElement.resetHistory();
     (emojiCompletion.render as sinon.SinonStub).resetHistory();
-
-    if (this.oldDocument === undefined) {
-      delete globalAsAny.document;
-    } else {
-      globalAsAny.document = this.oldDocument;
-    }
   });
 
   describe('getCurrentLeafTextPartitions', () => {

ts/test-electron/quill/mentions/completion_test.tsx

@@ -52,20 +52,6 @@ const members: Array<ConversationType> = [
   me,
 ];
 
-declare global {
-  // eslint-disable-next-line @typescript-eslint/no-namespace
-  namespace NodeJS {
-    interface Global {
-      document: {
-        body: {
-          appendChild: unknown;
-        };
-        createElement: unknown;
-      };
-    }
-  }
-}
-
 describe('MentionCompletion', () => {
   const mockSetMentionPickerElement = sinon.spy();
 
@@ -78,13 +64,6 @@ describe('MentionCompletion', () => {
   let mentionCompletion: MentionCompletion;
 
   beforeEach(function beforeEach() {
-    global.document = {
-      body: {
-        appendChild: sinon.spy(),
-      },
-      createElement: sinon.spy(),
-    };
-
     const memberRepositoryRef: MutableRefObject<MemberRepository> = {
       current: new MemberRepository(members),
     };