diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 66fb28ae318..78151f0b8e2 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -2074,13 +2074,31 @@ declare module 'vscode' {
 		 * Returns an observer that retrieves tests in the given text document.
 		 */
 		export function createDocumentTestObserver(document: TextDocument): TestObserver;
+
+		/**
+		 * The last or selected test run. Cleared when a new test run starts.
+		 */
+		export const testResults: TestResults | undefined;
+
+		/**
+		 * Event that fires when the testResults are updated.
+		 */
+		export const onDidChangeTestResults: Event<void>;
+	}
+
+	export interface TestResults {
+		/**
+		 * The results from the latest test run. The array contains a snapshot of
+		 * all tests involved in the run at the moment when it completed.
+		 */
+		readonly tests: ReadonlyArray<RequiredTestItem> | undefined;
 	}
 
 	export interface TestObserver {
 		/**
 		 * List of tests returned by test provider for files in the workspace.
 		 */
-		readonly tests: ReadonlyArray<TestItem>;
+		readonly tests: ReadonlyArray<RequiredTestItem>;
 
 		/**
 		 * An event that fires when an existing test in the collection changes, or
@@ -2110,23 +2128,23 @@ declare module 'vscode' {
 		/**
 		 * List of all tests that are newly added.
 		 */
-		readonly added: ReadonlyArray<TestItem>;
+		readonly added: ReadonlyArray<RequiredTestItem>;
 
 		/**
 		 * List of existing tests that have updated.
 		 */
-		readonly updated: ReadonlyArray<TestItem>;
+		readonly updated: ReadonlyArray<RequiredTestItem>;
 
 		/**
 		 * List of existing tests that have been removed.
 		 */
-		readonly removed: ReadonlyArray<TestItem>;
+		readonly removed: ReadonlyArray<RequiredTestItem>;
 
 		/**
 		 * Highest node in the test tree under which changes were made. This can
 		 * be easily plugged into events like the TreeDataProvider update event.
 		 */
-		readonly commonChangeAncestor: TestItem | null;
+		readonly commonChangeAncestor: RequiredTestItem | null;
 	}
 
 	/**
@@ -2232,6 +2250,16 @@ declare module 'vscode' {
 		 */
 		label: string;
 
+		/**
+		 * Optional unique identifier for the TestItem. This is used to correlate
+		 * test results and tests in the document with those in the workspace
+		 * (test explorer). This must not change for the lifetime of a test item.
+		 *
+		 * If the ID is not provided, it defaults to the concatenation of the
+		 * item's label and its parent's ID, if any.
+		 */
+		readonly id?: string;
+
 		/**
 		 * Optional description that appears next to the label.
 		 */
@@ -2268,6 +2296,15 @@ declare module 'vscode' {
 		state: TestState;
 	}
 
+	/**
+	 * A {@link TestItem} with its defaults filled in.
+	 */
+	export type RequiredTestItem = {
+		[K in keyof Required<TestItem>]: K extends 'children'
+		? RequiredTestItem[]
+		: (K extends 'description' | 'location' ? TestItem[K] : Required<TestItem>[K])
+	};
+
 	export enum TestRunState {
 		// Initial state
 		Unset = 0,
diff --git a/src/vs/workbench/api/browser/mainThreadTesting.ts b/src/vs/workbench/api/browser/mainThreadTesting.ts
index 95fc3087629..370f08df900 100644
--- a/src/vs/workbench/api/browser/mainThreadTesting.ts
+++ b/src/vs/workbench/api/browser/mainThreadTesting.ts
@@ -4,10 +4,11 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { CancellationToken } from 'vs/base/common/cancellation';
-import { Disposable, IDisposable } from 'vs/base/common/lifecycle';
+import { Disposable, IDisposable, MutableDisposable } from 'vs/base/common/lifecycle';
 import { URI, UriComponents } from 'vs/base/common/uri';
 import { extHostNamedCustomer } from 'vs/workbench/api/common/extHostCustomers';
 import { getTestSubscriptionKey, RunTestsRequest, RunTestsResult, TestDiffOpType, TestsDiff } from 'vs/workbench/contrib/testing/common/testCollection';
+import { ITestResultService } from 'vs/workbench/contrib/testing/common/testResultService';
 import { ITestService } from 'vs/workbench/contrib/testing/common/testService';
 import { ExtHostContext, ExtHostTestingResource, ExtHostTestingShape, IExtHostContext, MainContext, MainThreadTestingShape } from '../common/extHost.protocol';
 
@@ -36,13 +37,25 @@ export class MainThreadTesting extends Disposable implements MainThreadTestingSh
 	constructor(
 		extHostContext: IExtHostContext,
 		@ITestService private readonly testService: ITestService,
+		@ITestResultService resultService: ITestResultService,
 	) {
 		super();
 		this.proxy = extHostContext.getProxy(ExtHostContext.ExtHostTesting);
 		this._register(this.testService.onShouldSubscribe(args => this.proxy.$subscribeToTests(args.resource, args.uri)));
 		this._register(this.testService.onShouldUnsubscribe(args => this.proxy.$unsubscribeFromTests(args.resource, args.uri)));
+
+		const testCompleteListener = this._register(new MutableDisposable());
+		this._register(resultService.onNewTestResult(results => {
+			testCompleteListener.value = results.onComplete(() => this.proxy.$publishTestResults({ tests: results.tests }));
+		}));
+
 		testService.updateRootProviderCount(1);
 
+		const lastCompleted = resultService.results.find(r => !r.isComplete);
+		if (lastCompleted) {
+			this.proxy.$publishTestResults({ tests: lastCompleted.tests });
+		}
+
 		for (const { resource, uri } of this.testService.subscriptions) {
 			this.proxy.$subscribeToTests(resource, uri);
 		}
diff --git a/src/vs/workbench/api/common/extHost.api.impl.ts b/src/vs/workbench/api/common/extHost.api.impl.ts
index 2e246091426..1907f2993ad 100644
--- a/src/vs/workbench/api/common/extHost.api.impl.ts
+++ b/src/vs/workbench/api/common/extHost.api.impl.ts
@@ -340,6 +340,14 @@ export function createApiFactoryAndRegisterActors(accessor: ServicesAccessor): I
 				checkProposedApiEnabled(extension);
 				return extHostTesting.runTests(provider);
 			},
+			get onDidChangeTestResults() {
+				checkProposedApiEnabled(extension);
+				return extHostTesting.onLastResultsChanged;
+			},
+			get testResults() {
+				checkProposedApiEnabled(extension);
+				return extHostTesting.lastResults;
+			},
 		};
 
 		// namespace: extensions
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index 16e194fc063..0f2d3d55700 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -58,7 +58,7 @@ import { ISerializableEnvironmentVariableCollection } from 'vs/workbench/contrib
 import { DebugConfigurationProviderTriggerKind } from 'vs/workbench/api/common/extHostTypes';
 import { IAccessibilityInformation } from 'vs/platform/accessibility/common/accessibility';
 import { IExtensionIdWithVersion } from 'vs/platform/userDataSync/common/extensionsStorageSync';
-import { InternalTestItem, RunTestForProviderRequest, RunTestsRequest, RunTestsResult, TestIdWithProvider, TestsDiff } from 'vs/workbench/contrib/testing/common/testCollection';
+import { InternalTestItem, InternalTestResults, RunTestForProviderRequest, RunTestsRequest, RunTestsResult, TestIdWithProvider, TestsDiff } from 'vs/workbench/contrib/testing/common/testCollection';
 import { CandidatePort } from 'vs/workbench/services/remote/common/remoteExplorerService';
 
 export interface IEnvironment {
@@ -1843,6 +1843,7 @@ export interface ExtHostTestingShape {
 	$unsubscribeFromTests(resource: ExtHostTestingResource, uri: UriComponents): void;
 	$lookupTest(test: TestIdWithProvider): Promise<InternalTestItem | undefined>;
 	$acceptDiff(resource: ExtHostTestingResource, uri: UriComponents, diff: TestsDiff): void;
+	$publishTestResults(results: InternalTestResults): void;
 }
 
 export interface MainThreadTestingShape {
diff --git a/src/vs/workbench/api/common/extHostTesting.ts b/src/vs/workbench/api/common/extHostTesting.ts
index 6e51482cf5c..fb30845668e 100644
--- a/src/vs/workbench/api/common/extHostTesting.ts
+++ b/src/vs/workbench/api/common/extHostTesting.ts
@@ -17,15 +17,16 @@ import { ExtHostDocumentData } from 'vs/workbench/api/common/extHostDocumentData
 import { IExtHostDocumentsAndEditors } from 'vs/workbench/api/common/extHostDocumentsAndEditors';
 import { IExtHostRpcService } from 'vs/workbench/api/common/extHostRpcService';
 import { TestItem } from 'vs/workbench/api/common/extHostTypeConverters';
-import { Disposable, RequiredTestItem } from 'vs/workbench/api/common/extHostTypes';
+import { Disposable } from 'vs/workbench/api/common/extHostTypes';
 import { IExtHostWorkspace } from 'vs/workbench/api/common/extHostWorkspace';
 import { OwnedTestCollection, SingleUseTestCollection } from 'vs/workbench/contrib/testing/common/ownedTestCollection';
-import { AbstractIncrementalTestCollection, EMPTY_TEST_RESULT, IncrementalChangeCollector, IncrementalTestCollectionItem, InternalTestItem, RunTestForProviderRequest, RunTestsResult, TestDiffOpType, TestIdWithProvider, TestsDiff } from 'vs/workbench/contrib/testing/common/testCollection';
+import { AbstractIncrementalTestCollection, EMPTY_TEST_RESULT, IncrementalChangeCollector, IncrementalTestCollectionItem, InternalTestItem, InternalTestItemWithChildren, InternalTestResults, RunTestForProviderRequest, RunTestsResult, TestDiffOpType, TestIdWithProvider, TestsDiff } from 'vs/workbench/contrib/testing/common/testCollection';
 import type * as vscode from 'vscode';
 
 const getTestSubscriptionKey = (resource: ExtHostTestingResource, uri: URI) => `${resource}:${uri.toString()}`;
 
 export class ExtHostTesting implements ExtHostTestingShape {
+	private readonly resultsChangedEmitter = new Emitter<void>();
 	private readonly providers = new Map<string, vscode.TestProvider>();
 	private readonly proxy: MainThreadTestingShape;
 	private readonly ownedTests = new OwnedTestCollection();
@@ -38,6 +39,9 @@ export class ExtHostTesting implements ExtHostTestingShape {
 	private workspaceObservers: WorkspaceFolderTestObserverFactory;
 	private textDocumentObservers: TextDocumentTestObserverFactory;
 
+	public onLastResultsChanged = this.resultsChangedEmitter.event;
+	public lastResults?: vscode.TestResults;
+
 	constructor(@IExtHostRpcService rpc: IExtHostRpcService, @IExtHostDocumentsAndEditors private readonly documents: IExtHostDocumentsAndEditors, @IExtHostWorkspace private readonly workspace: IExtHostWorkspace) {
 		this.proxy = rpc.getProxy(MainContext.MainThreadTesting);
 		this.workspaceObservers = new WorkspaceFolderTestObserverFactory(this.proxy);
@@ -98,6 +102,19 @@ export class ExtHostTesting implements ExtHostTestingShape {
 		}, token);
 	}
 
+
+	/**
+	 * Updates test results shown to extensions.
+	 * @override
+	 */
+	public $publishTestResults(results: InternalTestResults): void {
+		const convert = (item: InternalTestItemWithChildren): vscode.RequiredTestItem =>
+			({ ...TestItem.toShallow(item.item), children: item.children.map(convert) });
+
+		this.lastResults = { tests: results.tests.map(convert) };
+		this.resultsChangedEmitter.fire();
+	}
+
 	/**
 	 * Handles a request to read tests for a file, or workspace.
 	 * @override
@@ -398,7 +415,7 @@ export class TestItemFilteredWrapper implements vscode.TestItem {
 interface MirroredCollectionTestItem extends IncrementalTestCollectionItem {
 	revived: vscode.TestItem;
 	depth: number;
-	wrapped?: vscode.TestItem;
+	wrapped?: vscode.RequiredTestItem;
 }
 
 class MirroredChangeCollector extends IncrementalChangeCollector<MirroredCollectionTestItem> {
@@ -427,7 +444,7 @@ class MirroredChangeCollector extends IncrementalChangeCollector<MirroredCollect
 	 * @override
 	 */
 	public update(node: MirroredCollectionTestItem): void {
-		Object.assign(node.revived, TestItem.to(node.item));
+		Object.assign(node.revived, TestItem.toShallow(node.item));
 		if (!this.added.has(node)) {
 			this.updated.add(node);
 		}
@@ -561,8 +578,8 @@ export class MirroredTestCollection extends AbstractIncrementalTestCollection<Mi
 	/**
 	 * Translates the item IDs to TestItems for exposure to extensions.
 	 */
-	public getAllAsTestItem(itemIds: Iterable<string>): vscode.TestItem[] {
-		let output: vscode.TestItem[] = [];
+	public getAllAsTestItem(itemIds: Iterable<string>): vscode.RequiredTestItem[] {
+		let output: vscode.RequiredTestItem[] = [];
 		for (const itemId of itemIds) {
 			const item = this.items.get(itemId);
 			if (item) {
@@ -593,7 +610,7 @@ export class MirroredTestCollection extends AbstractIncrementalTestCollection<Mi
 	 * @override
 	 */
 	protected createItem(item: InternalTestItem, parent?: MirroredCollectionTestItem): MirroredCollectionTestItem {
-		return { ...item, revived: TestItem.to(item.item), depth: parent ? parent.depth + 1 : 0, children: new Set() };
+		return { ...item, revived: TestItem.toShallow(item.item), depth: parent ? parent.depth + 1 : 0, children: new Set() };
 	}
 
 	/**
@@ -606,9 +623,9 @@ export class MirroredTestCollection extends AbstractIncrementalTestCollection<Mi
 	/**
 	 * Gets the public test item instance for the given mirrored record.
 	 */
-	public getPublicTestItem(item: MirroredCollectionTestItem): vscode.TestItem {
+	public getPublicTestItem(item: MirroredCollectionTestItem): vscode.RequiredTestItem {
 		if (!item.wrapped) {
-			item.wrapped = new ExtHostTestItem(item, this);
+			item.wrapped = new TestItemFromMirror(item, this);
 		}
 
 		return item.wrapped;
@@ -621,10 +638,11 @@ const getMirroredItemId = (item: vscode.TestItem) => {
 
 const MirroredItemId = Symbol('MirroredItemId');
 
-class ExtHostTestItem implements vscode.TestItem, RequiredTestItem {
+class TestItemFromMirror implements vscode.RequiredTestItem {
 	readonly #internal: MirroredCollectionTestItem;
 	readonly #collection: MirroredTestCollection;
 
+	public get id() { return this.#internal.revived.id!; }
 	public get label() { return this.#internal.revived.label; }
 	public get description() { return this.#internal.revived.description; }
 	public get state() { return this.#internal.revived.state; }
@@ -643,14 +661,15 @@ class ExtHostTestItem implements vscode.TestItem, RequiredTestItem {
 	}
 
 	public toJSON() {
-		const serialized: RequiredTestItem & TestIdWithProvider = {
+		const serialized: vscode.RequiredTestItem & TestIdWithProvider = {
+			id: this.id,
 			label: this.label,
 			description: this.description,
 			state: this.state,
 			location: this.location,
 			runnable: this.runnable,
 			debuggable: this.debuggable,
-			children: this.children.map(c => (c as ExtHostTestItem).toJSON()),
+			children: this.children.map(c => (c as TestItemFromMirror).toJSON()),
 
 			providerId: this.#internal.providerId,
 			testId: this.#internal.id,
diff --git a/src/vs/workbench/api/common/extHostTypeConverters.ts b/src/vs/workbench/api/common/extHostTypeConverters.ts
index 526193c85d1..d1512e59b87 100644
--- a/src/vs/workbench/api/common/extHostTypeConverters.ts
+++ b/src/vs/workbench/api/common/extHostTypeConverters.ts
@@ -1412,8 +1412,9 @@ export namespace TestState {
 
 
 export namespace TestItem {
-	export function from(item: vscode.TestItem): ITestItem {
+	export function from(item: vscode.TestItem, parentExtId?: string): ITestItem {
 		return {
+			extId: item.id ?? (parentExtId ? `${parentExtId}\0${item.label}` : item.label),
 			label: item.label,
 			location: item.location ? location.from(item.location) : undefined,
 			debuggable: item.debuggable ?? false,
@@ -1423,8 +1424,9 @@ export namespace TestItem {
 		};
 	}
 
-	export function to(item: ITestItem): vscode.TestItem {
+	export function toShallow(item: ITestItem): Omit<vscode.RequiredTestItem, 'children'> {
 		return {
+			id: item.extId,
 			label: item.label,
 			location: item.location && location.to({
 				range: item.location.range,
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index 3e754de6dbe..d07624eac74 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -2978,15 +2978,7 @@ export class TestState {
 	}
 }
 
-type AllowedUndefined = 'description' | 'location';
-
-/**
- * Test item without any optional properties. Only some properties are
- * permitted to be undefined, but they must still exist.
- */
-export type RequiredTestItem = {
-	[K in keyof Required<vscode.TestItem>]: K extends AllowedUndefined ? vscode.TestItem[K] : Required<vscode.TestItem>[K]
-};
+export type RequiredTestItem = vscode.RequiredTestItem;
 
 export type TestItem = vscode.TestItem;
 
diff --git a/src/vs/workbench/contrib/testing/common/ownedTestCollection.ts b/src/vs/workbench/contrib/testing/common/ownedTestCollection.ts
index c989796a67c..41f4c891fc0 100644
--- a/src/vs/workbench/contrib/testing/common/ownedTestCollection.ts
+++ b/src/vs/workbench/contrib/testing/common/ownedTestCollection.ts
@@ -126,12 +126,13 @@ export class SingleUseTestCollection implements IDisposable {
 
 	private addItem(actual: ApiTestItem, providerId: string, parent: string | null) {
 		let internal = this.testItemToInternal.get(actual);
+		const parentItem = parent ? this.testIdToInternal.get(parent) : null;
 		if (!internal) {
 			internal = {
 				actual,
 				id: this.getId(),
 				parent,
-				item: TestItem.from(actual),
+				item: TestItem.from(actual, parentItem?.item.extId),
 				providerId,
 				previousChildren: new Set(),
 				previousEquals: itemEqualityComparator(actual),
@@ -141,7 +142,7 @@ export class SingleUseTestCollection implements IDisposable {
 			this.testIdToInternal.set(internal.id, internal);
 			this.diff.push([TestDiffOpType.Add, { id: internal.id, parent, providerId, item: internal.item }]);
 		} else if (!internal.previousEquals(actual)) {
-			internal.item = TestItem.from(actual);
+			internal.item = TestItem.from(actual, parentItem?.item.extId);
 			internal.previousEquals = itemEqualityComparator(actual);
 			this.diff.push([TestDiffOpType.Update, { id: internal.id, parent, providerId, item: internal.item }]);
 		}
@@ -200,6 +201,7 @@ export class SingleUseTestCollection implements IDisposable {
 }
 
 const keyMap: { [K in keyof Omit<RequiredTestItem, 'children'>]: null } = {
+	id: null,
 	label: null,
 	location: null,
 	state: null,
diff --git a/src/vs/workbench/contrib/testing/common/testCollection.ts b/src/vs/workbench/contrib/testing/common/testCollection.ts
index cee17ec7668..566146dc027 100644
--- a/src/vs/workbench/contrib/testing/common/testCollection.ts
+++ b/src/vs/workbench/contrib/testing/common/testCollection.ts
@@ -62,6 +62,8 @@ export interface ITestState {
  * The TestItem from .d.ts, as a plain object without children.
  */
 export interface ITestItem {
+	/** ID of the test given by the test provider */
+	extId: string;
 	label: string;
 	children?: never;
 	location: ModeLocation | undefined;
@@ -81,6 +83,14 @@ export interface InternalTestItem {
 	item: ITestItem;
 }
 
+export interface InternalTestItemWithChildren extends InternalTestItem {
+	children: InternalTestItemWithChildren[];
+}
+
+export interface InternalTestResults {
+	tests: InternalTestItemWithChildren[];
+}
+
 export const enum TestDiffOpType {
 	/** Adds a new test (with children) */
 	Add,
diff --git a/src/vs/workbench/contrib/testing/common/testResultService.ts b/src/vs/workbench/contrib/testing/common/testResultService.ts
index d2235b4bcfc..992081d3a77 100644
--- a/src/vs/workbench/contrib/testing/common/testResultService.ts
+++ b/src/vs/workbench/contrib/testing/common/testResultService.ts
@@ -8,7 +8,7 @@ import { generateUuid } from 'vs/base/common/uuid';
 import { IContextKey, IContextKeyService } from 'vs/platform/contextkey/common/contextkey';
 import { createDecorator } from 'vs/platform/instantiation/common/instantiation';
 import { TestRunState } from 'vs/workbench/api/common/extHostTypes';
-import { IncrementalTestCollectionItem, InternalTestItem, TestIdWithProvider } from 'vs/workbench/contrib/testing/common/testCollection';
+import { IncrementalTestCollectionItem, InternalTestItemWithChildren, TestIdWithProvider } from 'vs/workbench/contrib/testing/common/testCollection';
 import { TestingContextKeys } from 'vs/workbench/contrib/testing/common/testingContextKeys';
 import { isRunningState, statesInOrder } from 'vs/workbench/contrib/testing/common/testingStates';
 import { IMainThreadTestCollection } from 'vs/workbench/contrib/testing/common/testService';
@@ -50,9 +50,7 @@ const makeNode = (
 	return mapped;
 };
 
-export interface TestResultItem extends InternalTestItem {
-	children: TestResultItem[]
-}
+export interface TestResultItem extends InternalTestItemWithChildren { }
 
 /**
  * Results of a test. These are created when the test initially started running
diff --git a/src/vs/workbench/test/browser/api/extHostTesting.test.ts b/src/vs/workbench/test/browser/api/extHostTesting.test.ts
index 11838dab2a2..1be5d1bc114 100644
--- a/src/vs/workbench/test/browser/api/extHostTesting.test.ts
+++ b/src/vs/workbench/test/browser/api/extHostTesting.test.ts
@@ -17,6 +17,7 @@ import { Range } from 'vs/editor/common/core/range';
 const simplify = (item: TestItem) => {
 	if ('toJSON' in item) {
 		item = (item as any).toJSON();
+		delete (item as any).id;
 		delete (item as any).providerId;
 		delete (item as any).testId;
 	}
@@ -70,10 +71,10 @@ suite('ExtHost Testing', () => {
 			single.addRoot(tests, 'pid');
 			assert.deepStrictEqual(single.collectDiff(), [
 				[TestDiffOpType.Add, { id: '0', providerId: 'pid', parent: null, item: convert.TestItem.from(stubTest('root')) }],
-				[TestDiffOpType.Add, { id: '1', providerId: 'pid', parent: '0', item: convert.TestItem.from(stubTest('a')) }],
-				[TestDiffOpType.Add, { id: '2', providerId: 'pid', parent: '1', item: convert.TestItem.from(stubTest('aa')) }],
-				[TestDiffOpType.Add, { id: '3', providerId: 'pid', parent: '1', item: convert.TestItem.from(stubTest('ab')) }],
-				[TestDiffOpType.Add, { id: '4', providerId: 'pid', parent: '0', item: convert.TestItem.from(stubTest('b')) }],
+				[TestDiffOpType.Add, { id: '1', providerId: 'pid', parent: '0', item: convert.TestItem.from(stubTest('a'), 'root') }],
+				[TestDiffOpType.Add, { id: '2', providerId: 'pid', parent: '1', item: convert.TestItem.from(stubTest('aa'), 'root\0a') }],
+				[TestDiffOpType.Add, { id: '3', providerId: 'pid', parent: '1', item: convert.TestItem.from(stubTest('ab'), 'root\0a') }],
+				[TestDiffOpType.Add, { id: '4', providerId: 'pid', parent: '0', item: convert.TestItem.from(stubTest('b'), 'root') }],
 			]);
 		});
 
@@ -91,7 +92,7 @@ suite('ExtHost Testing', () => {
 			tests.children![0].description = 'Hello world'; /* item a */
 			single.onItemChange(tests, 'pid');
 			assert.deepStrictEqual(single.collectDiff(), [
-				[TestDiffOpType.Update, { id: '1', parent: '0', providerId: 'pid', item: convert.TestItem.from({ ...stubTest('a'), description: 'Hello world' }) }],
+				[TestDiffOpType.Update, { id: '1', parent: '0', providerId: 'pid', item: convert.TestItem.from({ ...stubTest('a'), description: 'Hello world' }, 'root') }],
 			]);
 
 			single.onItemChange(tests, 'pid');
@@ -121,7 +122,7 @@ suite('ExtHost Testing', () => {
 			single.onItemChange(tests, 'pid');
 
 			assert.deepStrictEqual(single.collectDiff(), [
-				[TestDiffOpType.Add, { id: '5', providerId: 'pid', parent: '1', item: convert.TestItem.from(child) }],
+				[TestDiffOpType.Add, { id: '5', providerId: 'pid', parent: '1', item: convert.TestItem.from(child, 'root\0a') }],
 			]);
 			assert.deepStrictEqual([...owned.idToInternal.keys()].sort(), ['0', '1', '2', '3', '4', '5']);
 			assert.strictEqual(single.itemToInternal.size, 6);