Unit testing Firestore with Robolectric

What feature would you like to see?

Demo: https://gitlab.com/drizzd/firebaserobodemo

I would like to test my app, including the Firestore code paths, with Robolectric. Unfortunately, Firestore and Robolectric depend on different versions of protobuf. I don’t suppose it makes sense to just exclude one of the two?

debugUnitTestCompileClasspath - Compile classpath for compilation 'debugUnitTest' (target  (androidJvm)).                                                                                          
+--- com.google.firebase:firebase-firestore:21.4.1                                                                                                                                                 
    +--- io.grpc:grpc-protobuf-lite:1.21.0                                                                                                                                                        
    |    +--- io.grpc:grpc-api:1.21.0 (*)                                                                                                                                                         
    |    \--- com.google.protobuf:protobuf-lite:3.0.1                                                                                                                                             
[...]                                                                                                                                                                                              
+--- org.robolectric:robolectric:4.3.1                                                                                                                                                             
|    +--- org.robolectric:shadows-framework:4.3.1                                                                                                                                                  
|    |    +--- com.google.android.apps.common.testing.accessibility.framework:accessibility-test-framework:2.1                                                                                     
|    |    |    \--- com.google.protobuf:protobuf-java:2.6.1                                                                                                                                        
|    |    \--- com.android.support:support-annotations:28.0.0      

There is also another issue with the SharedPreferences filename on Windows, for which I have submitted to Robolectric: https://github.com/robolectric/robolectric/issues/5529.

How would you use it?

I would like to use AndroidX Test unit tests which are based on Robolectric in order to efficiently test Android apps which use Firestore. Combined with the Firebase emulator suite it would make a very powerful testing environment.

Dependency Error

For reference, this is the runtime error:

java.lang.NoSuchMethodError: com.google.firestore.v1.MapValue.makeImmutable()V

	at com.google.firestore.v1.MapValue.<clinit>(com.google.firebase:firebase-firestore@@21.4.1:490)
	at com.google.firebase.firestore.UserDataReader.parseMap(com.google.firebase:firebase-firestore@@21.4.1:290)
	at com.google.firebase.firestore.UserDataReader.parseData(com.google.firebase:firebase-firestore@@21.4.1:251)
	at com.google.firebase.firestore.UserDataReader.convertAndParseDocumentData(com.google.firebase:firebase-firestore@@21.4.1:232)
	at com.google.firebase.firestore.UserDataReader.parseSetData(com.google.firebase:firebase-firestore@@21.4.1:75)
	at com.google.firebase.firestore.DocumentReference.set(com.google.firebase:firebase-firestore@@21.4.1:166)
	at com.google.firebase.firestore.DocumentReference.set(com.google.firebase:firebase-firestore@@21.4.1:146)

[var-const]

I believe the issue is that future.get blocks the same thread that the callback is going to be invoked on; therefore, the callback never gets a chance to be invoked. Trying out your repro app (thanks for preparing it!) with logging enabled (FirebaseFirestore.setLoggingEnabled(true)), I see that Firestore receives the response from the server, but the callback is never invoked. I’m not very familiar with how waiting for asynchronous events works in Robolectric, sorry; I don’t think this is something specific to Firestore. It would appear that you would need to call either flushForegroundThreadScheduler or flushBackgroundThreadScheduler before you can poll the future.

[drizzd]

That fixes the version conflict. However, the callbacks are not invoked in the following test. It passes after the 10 second sleep:

import android.content.Context
import androidx.test.core.app.ApplicationProvider
import androidx.test.ext.junit.runners.AndroidJUnit4
import org.junit.Test
import org.junit.runner.RunWith

@RunWith(AndroidJUnit4::class)
class FirebaseTest {
    private val context = ApplicationProvider.getApplicationContext<Context>()

    @Test
    fun write() {
        val settings = FirebaseFirestoreSettings.Builder()
            .setHost("127.0.0.1:8080")
            .setSslEnabled(false)
            .setPersistenceEnabled(false)
            .build()

        FirebaseApp.initializeApp(context)
        val firestore = FirebaseFirestore.getInstance()
        firestore.firestoreSettings = settings
        firestore.collection("ponys").document("foo").set(mapOf("key" to "bar"))
            .addOnSuccessListener {
                throw Exception("success")
            }
            .addOnFailureListener {
                throw Exception("failure")
            }
            .addOnCanceledListener {
                throw Exception("canceled")
            }
        Thread.sleep(10000)
    }

Looking at the network traffic, it seems that no GRPC/Protobuf traffic happens:

As opposed to the Node.js version which works as expected:

const firebase = require('firebase/app');
require('firebase/firestore');

let firebaseApp;

async function main() {
  firebaseInit();

  try {
    await run();
  } finally {
    firebaseDelete();
  }
}

function firebaseInit() {
  firebaseApp = firebase.initializeApp({
    apiKey: "<...>",
    authDomain: "<...>.firebaseapp.com",
    databaseURL: "https://<...>.firebaseio.com",
    projectId: "<...>",
    storageBucket: "<...>.appspot.com",
    messagingSenderId: "<...>",
    appId: "<...>"
  });
  firebaseApp.firestore().settings({
    host: 'localhost:8080',
    ssl: false
  });
}

function firebaseDelete() {
  firebaseApp.delete();
}

async function run() {
  let firestore = firebaseApp.firestore();
  await firestore.collection('ponys').doc('foo').set({key: 'bar'});
}
main();