Add onDidChangeActiveTab

src/vs/workbench/api/test/browser/extHostEditorTabs.test.ts

@@ -109,7 +109,7 @@ suite('ExtHostEditorTabs', function () {
 		);
 
 		let count = 0;
-		extHostEditorTabs.tabGroups.onDidChangeTabGroup(() => count++);
+		extHostEditorTabs.tabGroups.onDidChangeTabGroups(() => count++);
 
 		assert.strictEqual(count, 0);
 
@@ -339,7 +339,7 @@ suite('ExtHostEditorTabs', function () {
 		});
 		assert.throws(() => {
 			// @ts-expect-error write to readonly prop
-			extHostEditorTabs.tabGroups.onDidChangeTabGroup = undefined;
+			extHostEditorTabs.tabGroups.onDidChangeTabGroups = undefined;
 		});
 	});
 
@@ -493,4 +493,72 @@ suite('ExtHostEditorTabs', function () {
 		assert.strictEqual(extHostEditorTabs.tabGroups.groups.map(g => g.tabs).flat().length, 0);
 		assert.strictEqual(extHostEditorTabs.tabGroups.activeTabGroup?.activeTab, undefined);
 	});
+
+	test('Active tab change event', function () {
+
+		const extHostEditorTabs = new ExtHostEditorTabs(
+			SingleProxyRPCProtocol(new class extends mock<MainThreadEditorTabsShape>() {
+				// override/implement $moveTab or $closeTab
+			})
+		);
+
+		let activeTabChangeCount = 0;
+		extHostEditorTabs.tabGroups.onDidChangeActiveTab((activeTab) => {
+			if (activeTab.isActive === false) {
+				throw new Error('Active tab changed fired on inactive tab');
+			}
+			activeTabChangeCount++;
+		});
+
+		const tab1: IEditorTabDto = createTabDto({
+			id: 'uniquestring',
+			isActive: true,
+			label: 'label1',
+		});
+
+		const tab2: IEditorTabDto = createTabDto({
+			isActive: false,
+			id: 'uniquestring2',
+			label: 'label2',
+		});
+
+		const tab3: IEditorTabDto = createTabDto({
+			isActive: false,
+			id: 'uniquestring3',
+			label: 'label3',
+		});
+
+		extHostEditorTabs.$acceptEditorTabModel([{
+			isActive: true,
+			viewColumn: 0,
+			groupId: 12,
+			tabs: [tab1, tab2, tab3]
+		}]);
+
+		// Accepting a model doesn't fire an active tab change event
+		assert.strictEqual(activeTabChangeCount, 0);
+
+		// Switching active tab works
+		tab1.isActive = false;
+		tab2.isActive = true;
+		extHostEditorTabs.$acceptTabUpdate(12, tab1);
+		extHostEditorTabs.$acceptTabUpdate(12, tab2);
+		// The active tab changed so it is fired once
+		assert.strictEqual(activeTabChangeCount, 1);
+
+		//Closing tabs out works
+		tab3.isActive = true;
+		extHostEditorTabs.$acceptEditorTabModel([{
+			isActive: true,
+			viewColumn: 0,
+			groupId: 12,
+			tabs: [tab3]
+		}]);
+		// Accepting a model doesn't fire an active tab change event
+		assert.strictEqual(activeTabChangeCount, 1);
+		tab3.label = 'Foobar';
+		extHostEditorTabs.$acceptTabUpdate(12, tab3);
+		// Something related to the active tab changed
+		assert.strictEqual(activeTabChangeCount, 2);
+	});
 });