Upgraded to TypeScript 4, upgraded several other dependencies too.

package.json

@@ -35,20 +35,20 @@
         "@types/lodash": "^4.14.157",
         "@types/luxon": "^1.24.1",
         "@types/node-fetch": "^2.5.7",
-        "@typescript-eslint/eslint-plugin": "^3.6.1",
-        "@typescript-eslint/parser": "^3.6.1",
+        "@typescript-eslint/eslint-plugin": "^4.2.0",
+        "@typescript-eslint/parser": "^4.2.0",
         "cheerio": "^1.0.0-rc.3",
         "clean-webpack-plugin": "^3.0.0",
         "copy-webpack-plugin": "^6.0.3",
         "css-loader": "^3.6.0",
         "dotenv-webpack": "^2.0.0",
-        "eslint": "^7.4.0",
-        "eslint-config-prettier": "^6.11.0",
+        "eslint": "^7.9.0",
+        "eslint-config-prettier": "^6.12.0",
         "eslint-plugin-prettier": "^3.1.4",
         "file-loader": "^6.0.0",
-        "fork-ts-checker-webpack-plugin": "^5.0.7",
+        "fork-ts-checker-webpack-plugin": "^5.2.0",
         "html-webpack-plugin": "^4.3.0",
-        "jest": "^26.1.0",
+        "jest": "^26.4.2",
         "jest-canvas-mock": "^2.2.0",
         "mini-css-extract-plugin": "^0.9.0",
         "monaco-editor-webpack-plugin": "^1.9.0",
@@ -56,10 +56,10 @@
         "optimize-css-assets-webpack-plugin": "^5.0.3",
         "prettier": "^2.0.5",
         "terser-webpack-plugin": "^2.3.7",
-        "ts-jest": "^26.1.2",
-        "ts-loader": "^8.0.0",
-        "ts-node": "^8.10.2",
-        "typescript": "^3.9.6",
+        "ts-jest": "^26.4.0",
+        "ts-loader": "^8.0.4",
+        "ts-node": "^9.0.0",
+        "typescript": "^4.0.3",
         "webpack": "^4.43.0",
         "webpack-cli": "^3.3.12",
         "webpack-dev-server": "^3.11.0",

src/quest_editor/gui/EntityInfoView.test.ts

@@ -40,16 +40,20 @@ test("Renders correctly with an entity selected.", () => {
     });
 });
 
-test("When the view's element is focused the quest editor store's undo stack should become the current stack.", () =>
-    with_disposer(async disposer => {
+test("When the view's element is focused the quest editor store's undo stack should become the current stack.", () => {
+    with_disposer(disposer => {
         const store = create_quest_editor_store(disposer);
         const view = disposer.add(
             new EntityInfoView(disposer.add(new EntityInfoController(store))),
         );
 
+        // Append view element to DOM to make it focusable.
+        document.body.append(view.element);
+
         undo_manager.make_noop_current();
 
         view.element.focus();
 
         expect(undo_manager.current.val).toBe(store.undo);
-    }));
+    });
+});

src/quest_editor/gui/QuestInfoView.test.ts

@@ -31,10 +31,13 @@ test("Renders correctly with a current quest.", () =>
     }));
 
 test("When the view's element is focused the quest editor store's undo stack should become the current stack.", () =>
-    with_disposer(async disposer => {
+    with_disposer(disposer => {
         const store = create_quest_editor_store(disposer);
         const view = disposer.add(new QuestInfoView(disposer.add(new QuestInfoController(store))));
 
+        // Append view element to DOM to make it focusable.
+        document.body.append(view.element);
+
         undo_manager.make_noop_current();
 
         view.element.focus();