Add file watching behind experiment (#14920)

* Add file watching behind experiment

* Update tests

* Fix windows store watcher tests

Author: karthiknadig

src/client/pythonEnvironments/base/locators/lowLevel/fsWatchingLocator.ts

@@ -1,8 +1,10 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT License.
 
+import { DiscoveryVariants } from '../../../../common/experiments/groups';
 import { FileChangeType } from '../../../../common/platform/fileSystemWatcher';
 import { sleep } from '../../../../common/utils/async';
+import { inExperiment } from '../../../common/externalDependencies';
 import { watchLocationForPythonBinaries } from '../../../common/pythonBinariesWatcher';
 import { PythonEnvKind } from '../../info';
 import { LazyResourceBasedLocator } from '../common/resourceBasedLocator';
@@ -38,12 +40,14 @@ export abstract class FSWatchingLocator extends LazyResourceBasedLocator {
     }
 
     protected async initWatchers(): Promise<void> {
-        // Start the FS watchers.
-        let roots = await this.getRoots();
-        if (typeof roots === 'string') {
-            roots = [roots];
+        if (await inExperiment(DiscoveryVariants.discoverWithFileWatching)) {
+            // Start the FS watchers.
+            let roots = await this.getRoots();
+            if (typeof roots === 'string') {
+                roots = [roots];
+            }
+            roots.forEach((root) => this.startWatcher(root));
         }
-        roots.forEach((root) => this.startWatcher(root));
     }
 
     private startWatcher(root: string): void {

src/test/pythonEnvironments/discovery/locators/watcherTestUtils.ts

@@ -4,6 +4,8 @@
 import { assert } from 'chai';
 import * as fs from 'fs-extra';
 import * as path from 'path';
+import * as sinon from 'sinon';
+import { DiscoveryVariants } from '../../../../client/common/experiments/groups';
 import { traceWarning } from '../../../../client/common/logger';
 import { FileChangeType } from '../../../../client/common/platform/fileSystemWatcher';
 import { createDeferred, Deferred, sleep } from '../../../../client/common/utils/async';
@@ -14,7 +16,7 @@ import { ILocator } from '../../../../client/pythonEnvironments/base/locator';
 import { getEnvs } from '../../../../client/pythonEnvironments/base/locatorUtils';
 import { PythonEnvsChangedEvent } from '../../../../client/pythonEnvironments/base/watcher';
 import { getInterpreterPathFromDir } from '../../../../client/pythonEnvironments/common/commonUtils';
-import { arePathsSame } from '../../../../client/pythonEnvironments/common/externalDependencies';
+import * as externalDeps from '../../../../client/pythonEnvironments/common/externalDependencies';
 import { deleteFiles, PYTHON_PATH } from '../../../common';
 import { TEST_TIMEOUT } from '../../../constants';
 import { run } from './envTestUtils';
@@ -121,6 +123,7 @@ export function testLocatorWatcher(
     },
 ): void {
     let locator: ILocator & IDisposable;
+    let inExperimentStub: sinon.SinonStub;
     const venvs = new Venvs(root);
 
     async function waitForChangeToBeDetected(deferred: Deferred<void>) {
@@ -133,11 +136,16 @@ export function testLocatorWatcher(
 
     async function isLocated(executable: string): Promise<boolean> {
         const items = await getEnvs(locator.iterEnvs());
-        return items.some((item) => arePathsSame(item.executable.filename, executable));
+        return items.some((item) => externalDeps.arePathsSame(item.executable.filename, executable));
     }
 
     suiteSetup(() => venvs.cleanUp());
 
+    setup(() => {
+        inExperimentStub = sinon.stub(externalDeps, 'inExperiment');
+        inExperimentStub.withArgs(DiscoveryVariants.discoverWithFileWatching).resolves(true);
+    });
+
     async function setupLocator(onChanged: (e: PythonEnvsChangedEvent) => Promise<void>) {
         locator = options?.arg ? await createLocatorFactoryFunc(options.arg) : await createLocatorFactoryFunc();
         await getEnvs(locator.iterEnvs()); // Force the FS watcher to start.
@@ -149,6 +157,7 @@ export function testLocatorWatcher(
     teardown(async () => {
         await venvs.cleanUp();
         locator.dispose();
+        inExperimentStub.restore();
     });
 
     test('Detect a new environment', async () => {

src/test/pythonEnvironments/discovery/locators/windowsStoreLocator.test.ts

@@ -4,13 +4,15 @@
 import { assert } from 'chai';
 import * as fs from 'fs-extra';
 import * as path from 'path';
+import * as sinon from 'sinon';
+import { DiscoveryVariants } from '../../../../client/common/experiments/groups';
 import { traceWarning } from '../../../../client/common/logger';
 import { FileChangeType } from '../../../../client/common/platform/fileSystemWatcher';
 import { createDeferred, Deferred, sleep } from '../../../../client/common/utils/async';
 import { PythonEnvKind } from '../../../../client/pythonEnvironments/base/info';
 import { getEnvs } from '../../../../client/pythonEnvironments/base/locatorUtils';
 import { PythonEnvsChangedEvent } from '../../../../client/pythonEnvironments/base/watcher';
-import { arePathsSame } from '../../../../client/pythonEnvironments/common/externalDependencies';
+import * as externalDeps from '../../../../client/pythonEnvironments/common/externalDependencies';
 import { WindowsStoreLocator } from '../../../../client/pythonEnvironments/discovery/locators/services/windowsStoreLocator';
 import { TEST_TIMEOUT } from '../../../constants';
 import { TEST_LAYOUT_ROOT } from '../../common/commonTestConstants';
@@ -54,6 +56,7 @@ class WindowsStoreEnvs {
 }
 
 suite('Windows Store Locator', async () => {
+    let inExperimentStub: sinon.SinonStub;
     const testLocalAppData = path.join(TEST_LAYOUT_ROOT, 'storeApps');
     const testStoreAppRoot = path.join(testLocalAppData, 'Microsoft', 'WindowsApps');
     const windowsStoreEnvs = new WindowsStoreEnvs(testStoreAppRoot);
@@ -74,14 +77,19 @@ suite('Windows Store Locator', async () => {
 
     async function isLocated(executable: string): Promise<boolean> {
         const items = await getEnvs(locator.iterEnvs());
-        return items.some((item) => arePathsSame(item.executable.filename, executable));
+        return items.some((item) => externalDeps.arePathsSame(item.executable.filename, executable));
     }
 
     suiteSetup(async () => {
         process.env.LOCALAPPDATA = testLocalAppData;
         await windowsStoreEnvs.cleanUp();
     });
 
+    setup(() => {
+        inExperimentStub = sinon.stub(externalDeps, 'inExperiment');
+        inExperimentStub.withArgs(DiscoveryVariants.discoverWithFileWatching).resolves(true);
+    });
+
     async function setupLocator(onChanged: (e: PythonEnvsChangedEvent) => Promise<void>) {
         locator = new WindowsStoreLocator();
         await getEnvs(locator.iterEnvs()); // Force the watchers to start.
@@ -91,6 +99,7 @@ suite('Windows Store Locator', async () => {
     }
 
     teardown(async () => {
+        inExperimentStub.restore();
         await windowsStoreEnvs.cleanUp();
         await locator.dispose();
     });