Google Services for Library Gradle Plugin

This plugin creates a function fun googleServicesOptionsBuilder():FirebaseOptions.Builder which provides a FirebaseOptions.Builder object pre-populated with the values from the google-services.json file.

This plugin is non-drop-in replacement for the official Google Services Gradle Plugin. It is intended to be used in androidTest within libraries modules where the original plugin is not applicable.

Usage plugin

Plugins DSL

Add the following to your project's settings.gradle:

pluginManagement {
    repositories {
        gradlePluginPortal()
        google()
    }
}

Apply the plugin in your app's build.gradle.kts:

plugins {
    id("solutions.s4y.google-services") version "1.0.0-alpha01"
}

Or in build.gradle:

plugins {
    id 'solutions.s4y.google-services' version '1.0.0-alpha01'
}

Plugin configuration

Configure the plugin's behavior through the googleServiceLibrary block in build.gradle.kts:

googleServiceLibrary {
    // Application ID from Firebase console (required)
    // it will be used to find the app data in google-services.json 
    googleCloudAppId = "you.domain.app"
    
    // package name for the `fun googleServicesOptionsBuilder():FirebaseOptions.Builder` function
    // if not set, it will be the same as the `googleCloudAppId`
    
    classPackage = "com.example"
}

Usage generated code

In the build/generated directory will be created a file googleServicesOptionsBuilder.kt with the content like this:

package your.application.id
import com.google.firebase.FirebaseOptions

fun googleServicesOptionsBuilder():FirebaseOptions.Builder =
   FirebaseOptions.Builder()
     .setApiKey("sOMeR4nD0mK3y")
     .setProjectId("app-b838e")
     .setApplicationId("1:481001888013:android:1828764839b7af18da58be")
     .setDatabaseUrl("null")
     .setStorageBucket("app-b838e.appspot.com")

This function can be used in your tests to initialize the FirebaseApp:

private var initialized = false
fun firebaseInit() {
    if (!initialized) {
        val builder: FirebaseOptions.Builder = googleServicesOptionsBuilder()
        val options = builder.build()
        val app = ApplicationProvider.getApplicationContext<Application>()
        FirebaseApp.initializeApp(app, options, "[DEFAULT]")
        initialized = true
    }
}

Pay attention: unlike the original plugin, this plugin does not init the FirebaseApp automatically. You need to call firebaseInit() before the usage Firebase manually.

The convinent way to use the generated function is Junit rule:

Define rule in FirebaseRule.kt

package com.example.rules

private var initialized = false
class FirebaseRule: MethodRule {
    override fun apply(base: Statement, method: FrameworkMethod?, target: Any?): Statement {
        if (!initialized) {
            val builder: FirebaseOptions.Builder = googleServicesOptionsBuilder()
            val options = builder.build()
            val app = ApplicationProvider.getApplicationContext<Application>()
            FirebaseApp.initializeApp(app, options, "[DEFAULT]")
            initialized = true
        }
        return object : Statement() {
            override fun evaluate() {
                base.evaluate()
            }
        }
    }
}

... and use it in the test classes

import com.example.rules.FirebaseRule

class FirebaseSomeTest {

    @get:Rule
    val firebaseRule = FirebaseRule()

    @Test
    fun something_shouldDo(): Unit {
        // Firebase already initialized here
        val appContext = InstrumentationRegistry.getInstrumentation().targetContext

        FirebaseStorage.getInstance().reference.child("...").getFile(...)
        ...