feat(database): add database.useEmulator()

- detox needed another timer disable on android to succeed
- offline / online is flaky
- lots of the e2e databases tests themselves are flaky - did my best there
- database rules are injected dynamically using @firebase/rules-unit-testing which is nice

Author: mikehardy

.github/workflows/scripts/database.rules

@@ -0,0 +1,13 @@
+{
+  "rules": {
+    // Database in general is closed. Read/Write to anything but "tests/" will fail.
+    ".read": false,
+    ".write": false,
+
+    // ..."tests" node will succeed
+     "tests": {
+        ".read": true,
+        ".write": true,
+     }
+  }
+}

.github/workflows/scripts/firebase.json

@@ -3,10 +3,16 @@
     "rules": "firestore.rules",
     "indexes": "firestore.indexes.json"
   },
+  "database": {
+    "rules": "database.rules"
+  },
   "emulators": {
     "auth": {
       "port": "9099"
     },
+    "database": {
+      "port": "9000"
+    },
     "firestore": {
       "port": "8080"
     },

.github/workflows/scripts/start-firebase-emulator.sh

@@ -4,7 +4,7 @@ if ! [ -x "$(command -v firebase)" ]; then
   exit 1
 fi
 
-EMU_START_COMMAND="firebase emulators:start --only firestore,auth --project react-native-firebase-testing"
+EMU_START_COMMAND="firebase emulators:start --only auth,database,firestore --project react-native-firebase-testing"
 
 if [ "$1" == "--no-daemon" ]; then
   $EMU_START_COMMAND

docs/database/usage/index.md

@@ -307,34 +307,6 @@ database and the new [`DataSnapshot`](/reference/database/datasnapshot) containi
 It is important that you understand how to write rules in your Firebase console to ensure that your data is secure.
 Please follow the Firebase Realtime Database documentation on [security](https://firebase.google.com/docs/database/security)
 
-# Using Emulator
-
-The Realtime Database currently has no direct support to use Firebase emulator, meaning that there is no "useEmulator" function to be used.
-To use Firebase emulator with Realtime Database, please, refer to "Using a secondary database section" or use approach from the code snippet below:
-
-```
-// databaseWrapper.js
-import {firebase} from '@react-native-firebase/database';
-
-class DatabaseWrapper {
-  constructor(){
-    if(__DEV__){
-      // setup correct address and port of the firebase emulator
-      this.database = firebase.app().database("http://localhost:9000?ns=YOUR_EMULATOR_DATABASE_NAME");
-    } else {
-      this.database = firebase.app().database("http://yourProductionUrl?ns=YOUR_PRODUCTION_DATABASE_NAME");
-    }
-  }
-}
-export const RealtimeDatabase = new DatabaseWrapper();
-
-
-//fetchData.js
-import {RealtimeDatabase} from "./databaseWrapper.js"
-
-const myRealtimeRef = RealtimeDatabase.database.ref("1234")...
-```
-
 # Using a secondary database
 
 If the default installed Firebase instance needs to address a different database within the same project, call the database method on the default app with passing the database URL.

jest.setup.ts

@@ -41,6 +41,10 @@ jest.doMock('react-native', () => {
           useEmulator: jest.fn(),
         },
         RNFBCrashlyticsModule: {},
+        RNFBDatabaseModule: {
+          on: jest.fn(),
+          useEmulator: jest.fn(),
+        },
         RNFBPerfModule: {},
       },
     },

packages/database/__tests__/database.test.ts

@@ -0,0 +1,46 @@
+import database, { firebase } from '../lib';
+
+describe('Database', function () {
+  describe('namespace', function () {
+    it('accessible from firebase.app()', function () {
+      const app = firebase.app();
+      expect(app.database).toBeDefined();
+      expect(app.database().useEmulator).toBeDefined();
+    });
+  });
+
+  describe('useEmulator()', function () {
+    it('useEmulator requires a string host', function () {
+      // @ts-ignore because we pass an invalid argument...
+      expect(() => database().useEmulator()).toThrow(
+        'firebase.database().useEmulator() takes a non-empty host',
+      );
+      expect(() => database().useEmulator('', -1)).toThrow(
+        'firebase.database().useEmulator() takes a non-empty host',
+      );
+      // @ts-ignore because we pass an invalid argument...
+      expect(() => database().useEmulator(123)).toThrow(
+        'firebase.database().useEmulator() takes a non-empty host',
+      );
+    });
+
+    it('useEmulator requires a host and port', function () {
+      expect(() => database().useEmulator('', 9000)).toThrow(
+        'firebase.database().useEmulator() takes a non-empty host and port',
+      );
+      // No port
+      // @ts-ignore because we pass an invalid argument...
+      expect(() => database().useEmulator('localhost')).toThrow(
+        'firebase.database().useEmulator() takes a non-empty host and port',
+      );
+    });
+
+    it('useEmulator -> remaps Android loopback to host', function () {
+      const foo = database().useEmulator('localhost', 9000);
+      expect(foo).toEqual(['10.0.2.2', 9000]);
+
+      const bar = database().useEmulator('127.0.0.1', 9000);
+      expect(bar).toEqual(['10.0.2.2', 9000]);
+    });
+  });
+});

packages/database/android/src/main/java/io/invertase/firebase/database/UniversalFirebaseDatabaseCommon.java

@@ -27,6 +27,7 @@
 
 public class UniversalFirebaseDatabaseCommon {
   private static HashMap<String, Boolean> configSettingsLock = new HashMap<>();
+  private static HashMap<String, HashMap<String, Object>> emulatorConfigs = new HashMap<>();
 
   static FirebaseDatabase getDatabaseForApp(String appName, String dbURL) {
     FirebaseDatabase firebaseDatabase;
@@ -45,6 +46,11 @@ static FirebaseDatabase getDatabaseForApp(String appName, String dbURL) {
 
     setDatabaseConfig(firebaseDatabase, appName, dbURL);
 
+    HashMap emulatorConfig = getEmulatorConfig(appName, dbURL);
+    if (emulatorConfig != null) {
+      firebaseDatabase.useEmulator((String)emulatorConfig.get("host"), (Integer)emulatorConfig.get("port"));
+    }
+
     return firebaseDatabase;
   }
 
@@ -83,4 +89,17 @@ private static void setDatabaseConfig(FirebaseDatabase firebaseDatabase, String
 
     configSettingsLock.put(lockKey, true);
   }
+
+  static void addEmulatorConfig(String appName, String dbURL, String host, int port) {
+    System.err.println("adding emulator config");
+    String configKey = appName + dbURL;
+    HashMap<String, Object> emulatorConfig = new HashMap<>();
+    emulatorConfig.put("host", host);
+    emulatorConfig.put("port", new Integer(port));
+    emulatorConfigs.put(configKey, emulatorConfig);
+  }
+
+  private static HashMap<String, Object> getEmulatorConfig(String appName, String dbURL) {
+    return emulatorConfigs.get(appName + dbURL);
+  }
 }

packages/database/android/src/main/java/io/invertase/firebase/database/UniversalFirebaseDatabaseModule.java

@@ -30,7 +30,6 @@ public class UniversalFirebaseDatabaseModule extends UniversalFirebaseModule {
     super(context, serviceName);
   }
 
-
   Task<Void> goOnline(String appName, String dbURL) {
     return Tasks.call(() -> {
       getDatabaseForApp(appName, dbURL).goOnline();

packages/database/android/src/reactnative/java/io/invertase/firebase/database/ReactNativeFirebaseDatabaseModule.java

@@ -23,6 +23,8 @@
 import io.invertase.firebase.common.ReactNativeFirebaseModule;
 import io.invertase.firebase.common.UniversalFirebasePreferences;
 
+import static io.invertase.firebase.database.UniversalFirebaseDatabaseCommon.addEmulatorConfig;
+
 public class ReactNativeFirebaseDatabaseModule extends ReactNativeFirebaseModule {
   private static final String SERVICE_NAME = "Database";
   private final UniversalFirebaseDatabaseModule module;
@@ -77,4 +79,9 @@ public void setPersistenceCacheSizeBytes(String app, String dbURL, double cacheS
       (long) cacheSizeBytes
     );
   }
+
+  @ReactMethod
+  public void useEmulator(String app, String dbURL, String host, int port) {
+    addEmulatorConfig(app, dbURL, host, port);
+  }
 }

packages/database/e2e/helpers.js

@@ -1,7 +1,11 @@
+const testingUtils = require('@firebase/rules-unit-testing');
+
 // TODO make more unique?
 const ID = Date.now();
 
 const PATH = `tests/${ID}`;
+const DB_NAME = 'react-native-firebase-testing';
+const DB_RULES = `{ "rules": {".read": false, ".write": false, "tests": {".read": true, ".write": true } } }`;
 
 const CONTENT = {
   TYPES: {
@@ -34,6 +38,8 @@ exports.seed = function seed(path) {
   return Promise.all([
     firebase.database().ref(`${path}/types`).set(CONTENT.TYPES),
     firebase.database().ref(`${path}/query`).set(CONTENT.QUERY),
+    // The database emulator does not load rules correctly. We force them pre-test.
+    testingUtils.loadDatabaseRules({ databaseName: DB_NAME, rules: DB_RULES }),
   ]);
 };
 
@@ -43,3 +49,4 @@ exports.wipe = function wipe(path) {
 
 exports.PATH = PATH;
 exports.CONTENT = CONTENT;
+exports.DB_RULES = DB_RULES;