chore(null): null-correctness for test utils (#3035)

#### Description of changes

Adds test utility files noted by `yarn null:find` to strict-null set.

#### Pull request checklist
<!-- If a checklist item is not applicable to this change, write "n/a" in the checkbox -->
- [x] Addresses an existing issue: #2869
- [x] Ran `yarn fastpass`
- [x] Added/updated relevant unit test(s) (and ran `yarn test`)
- [n/a] Verified code coverage for the changes made. Check coverage report at: `<rootDir>/test-results/unit/coverage`
- [x] PR title *AND* final merge commit title both start with a semantic tag (`fix:`, `chore:`, `feat(feature-name):`, `refactor:`). See `CONTRIBUTING.md`.
- [n/a] (UI changes only) Added screenshots/GIFs to description above
- [n/a] (UI changes only) Verified usability with NVDA/JAWS

src/tests/end-to-end/common/manifest-overide.ts

@@ -24,6 +24,9 @@ export class ManifestOveride {
     private modifiedManifest: chrome.runtime.Manifest;
 
     public addTemporaryPermission(permissionToAdd: string): ManifestOveride {
+        if (this.modifiedManifest.permissions == null) {
+            this.modifiedManifest.permissions = [];
+        }
         this.modifiedManifest.permissions.push(permissionToAdd);
 
         return this;

src/tests/end-to-end/common/pretty-print-axe-violations.ts

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
+import { AxeResults } from 'axe-core';
+
 export interface PrintableAxeResultNode {
     selector: string[];
     failureSummary: string;
@@ -10,7 +12,7 @@ export interface PrintableAxeResult {
     nodes: PrintableAxeResultNode[];
 }
 
-export function prettyPrintAxeViolations(axeResults: AxeResult): PrintableAxeResult[] {
+export function prettyPrintAxeViolations(axeResults: AxeResults): PrintableAxeResult[] {
     const violations = axeResults.violations;
     const printableViolations: PrintableAxeResult[] = violations.map(result => {
         const nodeResults: PrintableAxeResultNode[] = result.nodes.map(node => {

src/tests/unit/common/simulated-browser-adapter.ts

@@ -41,7 +41,9 @@ export function createSimulatedBrowserAdapter(
     tabs: chrome.tabs.Tab[],
     windows: chrome.windows.Window[],
 ): SimulatedBrowserAdapter {
-    const mock: Partial<SimulatedBrowserAdapter> = Mock.ofType<BrowserAdapter>();
+    const mock: Partial<SimulatedBrowserAdapter> & IMock<BrowserAdapter> = Mock.ofType<
+        BrowserAdapter
+    >();
     mock.tabs = [...tabs];
     mock.windows = [...windows];
     mock.setup(m => m.addListenerOnConnect(It.is(isFunction))).callback(
@@ -63,13 +65,13 @@ export function createSimulatedBrowserAdapter(
         c => (mock.notifyWindowsFocusChanged = c),
     );
 
-    mock.setup(m => m.getRuntimeLastError()).returns(() => null);
+    mock.setup(m => m.getRuntimeLastError()).returns(() => undefined);
     mock.setup(m => m.getAllWindows(It.isAny())).returns(() =>
         Promise.resolve(mock.windows as Windows.Window[]),
     );
     mock.setup(m => m.getTab(It.isAny(), It.isAny(), It.isAny())).callback(
         (tabId, resolve, reject) => {
-            const matchingTabs = mock.tabs.filter(tab => tab.id === tabId);
+            const matchingTabs = mock.tabs!.filter(tab => tab.id === tabId);
             if (matchingTabs.length === 1) {
                 resolve(matchingTabs[0]);
             } else if (reject != null) {
@@ -79,7 +81,7 @@ export function createSimulatedBrowserAdapter(
     );
 
     mock.setup(m => m.tabsQuery(It.isAny())).returns(query => {
-        const result = mock.tabs.filter(
+        const result = mock.tabs!.filter(
             candidateTab =>
                 (query.active == null || query.active === candidateTab.active) &&
                 (query.windowId == null || query.windowId === candidateTab.windowId),
@@ -89,20 +91,21 @@ export function createSimulatedBrowserAdapter(
     });
 
     mock.updateTab = (tabId, changeInfo) => {
-        mock.tabs
-            .filter(tab => tab.id === tabId)
-            .forEach((tab, index) => {
-                mock.tabs[index] = { ...tab, ...changeInfo };
-                mock.notifyTabsOnUpdated(tabId, changeInfo, mock.tabs[index]);
-            });
+        mock.tabs!.filter(tab => tab.id === tabId).forEach((tab, index) => {
+            mock.tabs![index] = { ...tab, ...changeInfo };
+            mock.notifyTabsOnUpdated!(tabId, changeInfo, mock.tabs![index]);
+        });
     };
     mock.activateTab = tabToActivate => {
-        mock.tabs
-            .filter(tab => tab.windowId === tabToActivate.windowId)
-            .forEach((tab, index) => {
-                mock.tabs[index] = { ...tab, active: tabToActivate.id === tab.id };
+        mock.tabs!.filter(tab => tab.windowId === tabToActivate.windowId).forEach((tab, index) => {
+            mock.tabs![index] = { ...tab, active: tabToActivate.id === tab.id };
+        });
+        if (tabToActivate.id != null) {
+            mock.notifyTabsOnActivated!({
+                windowId: tabToActivate.windowId,
+                tabId: tabToActivate.id,
             });
-        mock.notifyTabsOnActivated({ windowId: tabToActivate.windowId, tabId: tabToActivate.id });
+        }
     };
     return mock as SimulatedBrowserAdapter;
 }

src/tests/unit/common/visualization-toggle-props-builder.ts

@@ -9,7 +9,7 @@ export class VisualizationTogglePropsBuilder extends BaseDataBuilder<Visualizati
         this.data = {
             checked: false,
             disabled: false,
-            visualizationName: null,
+            visualizationName: 'stub visualization name',
         } as VisualizationToggleProps;
     }
 }

tsconfig.strictNullChecks.json

@@ -238,7 +238,9 @@
         "./src/tests/end-to-end/common/element-identifiers/popup-page-element-identifiers.ts",
         "./src/tests/end-to-end/common/element-identifiers/target-page-selectors.ts",
         "./src/tests/end-to-end/common/force-test-failure.ts",
+        "./src/tests/end-to-end/common/manifest-overide.ts",
         "./src/tests/end-to-end/common/prepare-test-result-file-path.ts",
+        "./src/tests/end-to-end/common/pretty-print-axe-violations.ts",
         "./src/tests/end-to-end/common/timeouts.ts",
         "./src/tests/end-to-end/setup/test-resource-server-config.ts",
         "./src/tests/end-to-end/setup/test-setup.ts",
@@ -251,9 +253,11 @@
         "./src/tests/unit/common/it-is-function.ts",
         "./src/tests/unit/common/node-list-builder.ts",
         "./src/tests/unit/common/sample-test-data.ts",
+        "./src/tests/unit/common/simulated-browser-adapter.ts",
         "./src/tests/unit/common/test-document-creator.ts",
         "./src/tests/unit/common/tick.ts",
         "./src/tests/unit/common/typemoq-helper.ts",
+        "./src/tests/unit/common/visualization-toggle-props-builder.ts",
         "./src/tests/unit/jest-setup.ts",
         "./src/tests/unit/mock-helpers/chrome-event-mock.ts",
         "./src/tests/unit/mock-helpers/port-on-disconnect-mock.ts",