Add Firebase App Distribution to smoke tests (#3555)

Author: rachaprince

smoke-tests/build.gradle

@@ -71,6 +71,7 @@ dependencies {
   // Firebase
   implementation "com.google.firebase:firebase-analytics"
   implementation "com.google.firebase:firebase-annotations"
+  implementation "com.google.firebase:firebase-appdistribution"
   implementation "com.google.firebase:firebase-appindexing"
   implementation "com.google.firebase:firebase-auth"
   implementation "com.google.firebase:firebase-common"

smoke-tests/src/main/java/com/google/firebase/testing/BuildOnlyTest.java

@@ -21,6 +21,7 @@
 import com.google.firebase.messaging.FirebaseMessaging;
 import com.google.firebase.ml.modeldownloader.FirebaseModelDownloader;
 import com.google.firebase.perf.FirebasePerformance;
+import com.google.firebase.appdistribution.FirebaseAppDistribution;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.JUnit4;
@@ -55,4 +56,9 @@ public void modelDownloader_IsNotNull() {
   public void performance_IsNotNull() {
     assertThat(FirebasePerformance.getInstance()).isNotNull();
   }
+
+  @Test
+  public void appDistribution_IsNotNull(){
+    assertThat(FirebaseAppDistribution.getInstance()).isNotNull();
+  }
 }