Call the correct API to determine if a user is in treatment or control group (#20690)

Closes #20183

Author: Kartik Raj

.github/workflows/pr-check.yml

@@ -266,15 +266,6 @@ jobs:
           working-directory: ${{ env.special-working-directory }}
         if: matrix.test-suite == 'single-workspace'
 
-      - name: Run multi-workspace tests
-        env:
-          CI_PYTHON_VERSION: ${{ matrix.python }}
-        uses: GabrielBB/[email protected]
-        with:
-          run: npm run testMultiWorkspace
-          working-directory: ${{ env.special-working-directory }}
-        if: matrix.test-suite == 'multi-workspace'
-
       - name: Run debugger tests
         env:
           CI_PYTHON_VERSION: ${{ matrix.python }}

src/client/common/experiments/service.ts

@@ -142,7 +142,7 @@ export class ExperimentService implements IExperimentService {
         // it means that the value for this experiment was not found on the server.
         const treatmentVariable = this.experimentationService.getTreatmentVariable(EXP_CONFIG_ID, experiment);
 
-        return treatmentVariable !== undefined;
+        return treatmentVariable === true;
     }
 
     public async getExperimentValue<T extends boolean | number | string>(experiment: string): Promise<T | undefined> {

src/test/common/experiments/service.unit.test.ts

@@ -177,7 +177,7 @@ suite('Experimentation service', () => {
                     telemetryEvents.push(telemetry);
                 });
 
-            getTreatmentVariable = sinon.stub().returns(Promise.resolve(true));
+            getTreatmentVariable = sinon.stub().returns(true);
             sinon.stub(tasClient, 'getExperimentationService').returns(({
                 getTreatmentVariable,
             } as unknown) as tasClient.IExperimentationService);
@@ -205,6 +205,37 @@ suite('Experimentation service', () => {
             sinon.assert.calledOnce(getTreatmentVariable);
         });
 
+        test('If in control group, return false', async () => {
+            sinon.restore();
+            sendTelemetryEventStub = sinon
+                .stub(Telemetry, 'sendTelemetryEvent')
+                .callsFake((eventName: string, _, properties: unknown) => {
+                    const telemetry = { eventName, properties };
+                    telemetryEvents.push(telemetry);
+                });
+
+            // Control group returns false.
+            getTreatmentVariable = sinon.stub().returns(false);
+            sinon.stub(tasClient, 'getExperimentationService').returns(({
+                getTreatmentVariable,
+            } as unknown) as tasClient.IExperimentationService);
+
+            configureApplicationEnvironment('stable', extensionVersion);
+
+            configureSettings(true, [], []);
+
+            const experimentService = new ExperimentService(
+                instance(workspaceService),
+                instance(appEnvironment),
+                instance(stateFactory),
+            );
+            const result = experimentService.inExperimentSync(experiment);
+
+            assert.isFalse(result);
+            sinon.assert.notCalled(sendTelemetryEventStub);
+            sinon.assert.calledOnce(getTreatmentVariable);
+        });
+
         test('If the experiment setting is disabled, inExperiment should return false', async () => {
             configureSettings(false, [], []);