Add test

Author: edvilme

package-lock.json

@@ -0,0 +1,50 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+'use strict';
+
+import { expect } from 'chai';
+import { anything, reset, verify, when } from 'ts-mockito';
+import { Disposable, Uri } from 'vscode';
+import { mockedVSCodeNamespaces } from '../vscode-mock';
+import { RecommendedEnvironmentService } from '../../client/interpreter/configuration/recommededEnvironmentService';
+
+suite('RecommendedEnvironmentService - activate', () => {
+    let service: RecommendedEnvironmentService;
+    let subscriptions: Disposable[];
+
+    setup(() => {
+        subscriptions = [];
+        const extensionContext = {
+            subscriptions,
+            globalState: {
+                get: () => undefined,
+                update: () => Promise.resolve(),
+            },
+        } as any;
+
+        when(mockedVSCodeNamespaces.commands!.registerCommand(anything(), anything())).thenReturn({
+            dispose: () => {},
+        } as Disposable);
+
+        service = new RecommendedEnvironmentService(extensionContext);
+    });
+
+    teardown(() => {
+        reset(mockedVSCodeNamespaces.commands!);
+    });
+
+    test('Multiroot workspace: command is registered only once across multiple activate calls', async () => {
+        // Simulate multiroot workspace where activate is called once per workspace root
+        const workspaceRoot1 = Uri.file('/workspace/root1');
+        const workspaceRoot2 = Uri.file('/workspace/root2');
+        const workspaceRoot3 = Uri.file('/workspace/root3');
+
+        await service.activate(workspaceRoot1);
+        await service.activate(workspaceRoot2);
+        await service.activate(workspaceRoot3);
+
+        verify(mockedVSCodeNamespaces.commands!.registerCommand('python.getRecommendedEnvironment', anything())).once();
+        expect(subscriptions).to.have.lengthOf(1);
+    });
+});