Prevent duplicate startup work scheduling

Author: MihaiCristianCondrea

app/src/main/java/com/d4rk/androidtutorials/java/startup/StartupInitializer.java

@@ -3,17 +3,21 @@
 import android.content.Context;
 
 import androidx.annotation.NonNull;
+import androidx.annotation.VisibleForTesting;
 import androidx.work.ExistingWorkPolicy;
 import androidx.work.OneTimeWorkRequest;
 import androidx.work.WorkManager;
 
+import java.util.concurrent.atomic.AtomicBoolean;
+
 /**
  * Helper used to enqueue a one-off background job for initializing ads and
  * cookies. The work is only scheduled once per app launch sequence.
  */
 public final class StartupInitializer {
 
     private static final String WORK_NAME = "startup_init";
+    private static final AtomicBoolean HAS_SCHEDULED = new AtomicBoolean(false);
 
     private StartupInitializer() {
         // no-op
@@ -24,10 +28,19 @@ private StartupInitializer() {
      * is already enqueued, this call is ignored.
      */
     public static void schedule(@NonNull Context context) {
+        if (!HAS_SCHEDULED.compareAndSet(false, true)) {
+            return;
+        }
+
         OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(
                 StartupWorker.class).build();
         WorkManager.getInstance(context).enqueueUniqueWork(
                 WORK_NAME, ExistingWorkPolicy.KEEP, workRequest);
     }
+
+    @VisibleForTesting
+    static void resetForTesting() {
+        HAS_SCHEDULED.set(false);
+    }
 }
 

app/src/test/java/com/d4rk/androidtutorials/java/startup/StartupInitializerTest.java

@@ -6,6 +6,8 @@
 import androidx.work.OneTimeWorkRequest;
 import androidx.work.WorkManager;
 
+import org.junit.After;
+import org.junit.Before;
 import org.junit.Test;
 import org.mockito.MockedStatic;
 
@@ -14,9 +16,20 @@
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.mockStatic;
 import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
 
 public class StartupInitializerTest {
 
+    @Before
+    public void setUp() {
+        StartupInitializer.resetForTesting();
+    }
+
+    @After
+    public void tearDown() {
+        StartupInitializer.resetForTesting();
+    }
+
     @Test
     public void schedule_enqueuesWorkWithKeepPolicy() {
         Context context = mock(Context.class);
@@ -34,4 +47,24 @@ public void schedule_enqueuesWorkWithKeepPolicy() {
             );
         }
     }
+
+    @Test
+    public void schedule_multipleCalls_enqueuesWorkOnlyOnce() {
+        Context context = mock(Context.class);
+        WorkManager workManager = mock(WorkManager.class);
+
+        try (MockedStatic<WorkManager> mockedWorkManager = mockStatic(WorkManager.class)) {
+            mockedWorkManager.when(() -> WorkManager.getInstance(context)).thenReturn(workManager);
+
+            StartupInitializer.schedule(context);
+            StartupInitializer.schedule(context);
+
+            verify(workManager).enqueueUniqueWork(
+                    eq("startup_init"),
+                    eq(ExistingWorkPolicy.KEEP),
+                    any(OneTimeWorkRequest.class)
+            );
+            verifyNoMoreInteractions(workManager);
+        }
+    }
 }