Add unit test for gauges with multiple session IDs

Author: tejasd

firebase-perf/src/main/java/com/google/firebase/perf/session/gauges/GaugeManager.java

@@ -138,6 +138,7 @@ public void startCollectingGauges(PerfSession session) {
       stopCollectingGauges();
     }
 
+    // TODO(b/394127311): Explore always setting the app state as FOREGROUND.
     ApplicationProcessState gaugeCollectionApplicationProcessState = applicationProcessState;
     if (gaugeCollectionApplicationProcessState
         == ApplicationProcessState.APPLICATION_PROCESS_STATE_UNKNOWN) {

firebase-perf/src/test/java/com/google/firebase/perf/session/gauges/GaugeManagerTest.java

@@ -366,20 +366,17 @@ public void testGaugeCounterStartsAJobToConsumeTheGeneratedMetrics() {
   }
 
   @Test
-  public void testUpdateAppStateFlushesMetricsInTheCurrentAppState() {
+  public void testUpdateAppStateHandlesMultipleAppStates() {
     PerfSession fakeSession = createTestSession(1);
     fakeSession.setGaugeAndEventCollectionEnabled(true);
     testGaugeManager.setApplicationProcessState(ApplicationProcessState.FOREGROUND);
     testGaugeManager.startCollectingGauges(fakeSession);
     GaugeCounter.INSTANCE.setGaugeManager(testGaugeManager);
 
-    // There's no job to log the gauges.
-    assertThat(fakeScheduledExecutorService.isEmpty()).isTrue();
-
     // Generate metrics that don't exceed the GaugeCounter.MAX_COUNT.
     generateMetricsAndIncrementCounter(10);
 
-    // There's still no job to log the gauges.
+    // There's no job to log the gauges.
     assertThat(fakeScheduledExecutorService.isEmpty()).isTrue();
 
     testGaugeManager.onUpdateAppState(ApplicationProcessState.BACKGROUND);
@@ -389,9 +386,10 @@ public void testUpdateAppStateFlushesMetricsInTheCurrentAppState() {
         .isEqualTo(TIME_TO_WAIT_BEFORE_FLUSHING_GAUGES_QUEUE_MS);
 
     fakeScheduledExecutorService.simulateSleepExecutingAtMostOneTask();
+    shadowOf(Looper.getMainLooper()).idle();
 
-    // Generate additional metrics that shouldn't be included in the flush.
-    generateMetricsAndIncrementCounter(5);
+    // Generate additional metrics in the new app state.
+    generateMetricsAndIncrementCounter(26);
 
     GaugeMetric recordedGaugeMetric =
         getLastRecordedGaugeMetric(ApplicationProcessState.FOREGROUND);
@@ -403,6 +401,73 @@ public void testUpdateAppStateFlushesMetricsInTheCurrentAppState() {
     assertThat(recordedGaugeMetricsCount).isEqualTo(10);
 
     assertThat(recordedGaugeMetric.getSessionId()).isEqualTo(testSessionId(1));
+
+    // Simulate gauges collected in the new app state.
+    fakeScheduledExecutorService.simulateSleepExecutingAtMostOneTask();
+    shadowOf(Looper.getMainLooper()).idle();
+
+    recordedGaugeMetric = getLastRecordedGaugeMetric(ApplicationProcessState.BACKGROUND);
+
+    // Verify the metrics in the new app state.
+    recordedGaugeMetricsCount =
+        recordedGaugeMetric.getAndroidMemoryReadingsCount()
+            + recordedGaugeMetric.getCpuMetricReadingsCount();
+    assertThat(recordedGaugeMetricsCount).isEqualTo(26);
+
+    assertThat(recordedGaugeMetric.getSessionId()).isEqualTo(testSessionId(1));
+  }
+
+  @Test
+  public void testGaugeManagerHandlesMultipleSessionIds() {
+    PerfSession fakeSession = createTestSession(1);
+    fakeSession.setGaugeAndEventCollectionEnabled(true);
+    testGaugeManager.setApplicationProcessState(ApplicationProcessState.BACKGROUND);
+    testGaugeManager.startCollectingGauges(fakeSession);
+    GaugeCounter.INSTANCE.setGaugeManager(testGaugeManager);
+
+    // Generate metrics that don't exceed the GaugeCounter.MAX_COUNT.
+    generateMetricsAndIncrementCounter(10);
+
+    PerfSession updatedPerfSession = createTestSession(2);
+    updatedPerfSession.setGaugeAndEventCollectionEnabled(true);
+
+    // A new session and updated app state.
+    testGaugeManager.startCollectingGauges(updatedPerfSession);
+
+    assertThat(fakeScheduledExecutorService.isEmpty()).isFalse();
+    assertThat(fakeScheduledExecutorService.getDelayToNextTask(TimeUnit.MILLISECONDS))
+        .isEqualTo(TIME_TO_WAIT_BEFORE_FLUSHING_GAUGES_QUEUE_MS);
+
+    fakeScheduledExecutorService.simulateSleepExecutingAtMostOneTask();
+    shadowOf(Looper.getMainLooper()).idle();
+
+    // Generate metrics for the new session.
+    generateMetricsAndIncrementCounter(26);
+
+    GaugeMetric recordedGaugeMetric =
+        getLastRecordedGaugeMetric(ApplicationProcessState.BACKGROUND);
+
+    // It flushes all metrics in the ConcurrentLinkedQueues.
+    int recordedGaugeMetricsCount =
+        recordedGaugeMetric.getAndroidMemoryReadingsCount()
+            + recordedGaugeMetric.getCpuMetricReadingsCount();
+    assertThat(recordedGaugeMetricsCount).isEqualTo(10);
+
+    assertThat(recordedGaugeMetric.getSessionId()).isEqualTo(testSessionId(1));
+
+    // Simulate gauges collected in the new app state.
+    fakeScheduledExecutorService.simulateSleepExecutingAtMostOneTask();
+    shadowOf(Looper.getMainLooper()).idle();
+
+    recordedGaugeMetric = getLastRecordedGaugeMetric(ApplicationProcessState.BACKGROUND);
+
+    // Verify the metrics in the new app state.
+    recordedGaugeMetricsCount =
+        recordedGaugeMetric.getAndroidMemoryReadingsCount()
+            + recordedGaugeMetric.getCpuMetricReadingsCount();
+    assertThat(recordedGaugeMetricsCount).isEqualTo(26);
+
+    assertThat(recordedGaugeMetric.getSessionId()).isEqualTo(testSessionId(2));
   }
 
   @Test