Speed up SpecTest (#2969)

Author: schmidt-sebastian

firebase-firestore/src/main/java/com/google/firebase/firestore/remote/Datastore.java

@@ -92,10 +92,19 @@ public Datastore(
     this.databaseInfo = databaseInfo;
     this.workerQueue = workerQueue;
     this.serializer = new RemoteSerializer(databaseInfo.getDatabaseId());
+    this.channel =
+        initializeChannel(
+            databaseInfo, workerQueue, credentialsProvider, context, metadataProvider);
+  }
 
-    channel =
-        new FirestoreChannel(
-            workerQueue, context, credentialsProvider, databaseInfo, metadataProvider);
+  FirestoreChannel initializeChannel(
+      DatabaseInfo databaseInfo,
+      AsyncQueue workerQueue,
+      CredentialsProvider credentialsProvider,
+      Context context,
+      @Nullable GrpcMetadataProvider metadataProvider) {
+    return new FirestoreChannel(
+        workerQueue, context, credentialsProvider, databaseInfo, metadataProvider);
   }
 
   void shutdown() {

firebase-firestore/src/test/java/com/google/firebase/firestore/remote/MockDatastore.java

@@ -17,6 +17,8 @@
 import static com.google.firebase.firestore.util.Assert.hardAssert;
 
 import android.content.Context;
+import androidx.annotation.Nullable;
+import com.google.firebase.firestore.auth.CredentialsProvider;
 import com.google.firebase.firestore.core.DatabaseInfo;
 import com.google.firebase.firestore.local.TargetData;
 import com.google.firebase.firestore.model.SnapshotVersion;
@@ -218,6 +220,19 @@ public MockDatastore(DatabaseInfo databaseInfo, AsyncQueue workerQueue, Context
     this.serializer = new RemoteSerializer(getDatabaseInfo().getDatabaseId());
   }
 
+  @Override
+  FirestoreChannel initializeChannel(
+      DatabaseInfo databaseInfo,
+      AsyncQueue workerQueue,
+      CredentialsProvider credentialsProvider,
+      Context context,
+      @Nullable GrpcMetadataProvider metadataProvider) {
+    return null;
+  }
+
+  @Override
+  void shutdown() {}
+
   @Override
   WatchStream createWatchStream(WatchStream.Callback listener) {
     watchStream = new MockWatchStream(getWorkerQueue(), listener);