From db8565812159c28a16bb4fc025154a7d68c4eeba Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Tue, 2 Aug 2022 15:08:54 -0400
Subject: [PATCH 01/16] Multi DB Work In Progress

---
 packages/firestore/lite/register.ts    |  4 ++--
 packages/firestore/src/api/database.ts | 18 ++++++++++++++++--
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/packages/firestore/lite/register.ts b/packages/firestore/lite/register.ts
index 8409aad6aaf..5d7a8e6efaa 100644
--- a/packages/firestore/lite/register.ts
+++ b/packages/firestore/lite/register.ts
@@ -42,7 +42,7 @@ export function registerFirestore(): void {
   _registerComponent(
     new Component(
       'firestore/lite',
-      (container, { options: settings }: { options?: FirestoreSettings }) => {
+      (container, { instanceIdentifier: databaseId, options: settings }: { options?: FirestoreSettings }) => {
         const app = container.getProvider('app').getImmediate()!;
         const firestoreInstance = new Firestore(
           app,
@@ -59,7 +59,7 @@ export function registerFirestore(): void {
         return firestoreInstance;
       },
       'PUBLIC' as ComponentType.PUBLIC
-    )
+    ).setMultipleInstances(true)
   );
   // RUNTIME_ENV and BUILD_TARGET are replaced by real values during the compilation
   registerVersion('firestore-lite', version, '__RUNTIME_ENV__');
diff --git a/packages/firestore/src/api/database.ts b/packages/firestore/src/api/database.ts
index 7a71071b54b..9c9ed88ccc2 100644
--- a/packages/firestore/src/api/database.ts
+++ b/packages/firestore/src/api/database.ts
@@ -182,8 +182,22 @@ export function initializeFirestore(
  * instance is associated with.
  * @returns The {@link Firestore} instance of the provided app.
  */
-export function getFirestore(app: FirebaseApp = getApp()): Firestore {
-  return _getProvider(app, 'firestore').getImmediate() as Firestore;
+export function getFirestore(
+  app: FirebaseApp,
+  databaseId?: string
+): Firestore;
+export function getFirestore(
+  databaseId?: string
+): Firestore;
+export function getFirestore(
+  appOrDatabaseId?: FirebaseApp | string,
+  optionalDatabaseId?: string
+): Firestore {
+  const app: FirebaseApp = typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
+  const databaseId = typeof appOrDatabaseId === 'string' ? appOrDatabaseId : optionalDatabaseId || '(default)';
+  return _getProvider(app || getApp(), 'firestore').getImmediate({
+    identifier: databaseId
+  }) as Firestore;
 }
 
 /**

From b13378b46b3ef6600933db0682dacc7789842ce0 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Thu, 4 Aug 2022 17:30:59 -0400
Subject: [PATCH 02/16] Work in progress

---
 packages/firestore/lite/register.ts | 4 ++--
 packages/firestore/src/register.ts  | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/firestore/lite/register.ts b/packages/firestore/lite/register.ts
index 5d7a8e6efaa..2ec5f9a3b0e 100644
--- a/packages/firestore/lite/register.ts
+++ b/packages/firestore/lite/register.ts
@@ -20,7 +20,7 @@ import {
   registerVersion,
   SDK_VERSION
 } from '@firebase/app';
-import { Component, ComponentType } from '@firebase/component';
+import { Component, ComponentType, InstanceFactoryOptions } from '@firebase/component';
 
 import { version } from '../package.json';
 import {
@@ -42,7 +42,7 @@ export function registerFirestore(): void {
   _registerComponent(
     new Component(
       'firestore/lite',
-      (container, { instanceIdentifier: databaseId, options: settings }: { options?: FirestoreSettings }) => {
+      (container, { instanceIdentifier: databaseId, options: settings }) => {
         const app = container.getProvider('app').getImmediate()!;
         const firestoreInstance = new Firestore(
           app,
diff --git a/packages/firestore/src/register.ts b/packages/firestore/src/register.ts
index cf4cb83632a..1bcda165648 100644
--- a/packages/firestore/src/register.ts
+++ b/packages/firestore/src/register.ts
@@ -40,7 +40,7 @@ export function registerFirestore(
   _registerComponent(
     new Component(
       'firestore',
-      (container, { options: settings }: { options?: PrivateSettings }) => {
+      (container, { instanceIdentifier: databaseId, options: settings }) => {
         const app = container.getProvider('app').getImmediate()!;
         const firestoreInstance = new Firestore(
           app,

From ce6cf1d684124149661190ecd78a77b6723f636c Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Mon, 8 Aug 2022 15:49:44 -0400
Subject: [PATCH 03/16] MultiDb with Tests.

---
 common/api-review/firestore-lite.api.md       | 11 ++-
 common/api-review/firestore.api.md            | 11 ++-
 .../firestore-compat/src/index.console.ts     |  4 +-
 packages/firestore/lite/register.ts           |  6 +-
 packages/firestore/package.json               |  1 +
 packages/firestore/src/api/database.ts        | 48 +++++++++---
 packages/firestore/src/core/database_info.ts  | 14 ++++
 packages/firestore/src/lite-api/database.ts   | 77 ++++++++++++-------
 packages/firestore/src/register.ts            |  6 +-
 .../firestore/test/lite/integration.test.ts   | 49 +++++++++++-
 packages/firestore/test/util/api_helpers.ts   |  4 +-
 11 files changed, 178 insertions(+), 53 deletions(-)

diff --git a/common/api-review/firestore-lite.api.md b/common/api-review/firestore-lite.api.md
index a96f3ada5cb..c69f9d2da25 100644
--- a/common/api-review/firestore-lite.api.md
+++ b/common/api-review/firestore-lite.api.md
@@ -176,7 +176,16 @@ export function getDoc<T>(reference: DocumentReference<T>): Promise<DocumentSnap
 export function getDocs<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
 
 // @public
-export function getFirestore(app?: FirebaseApp): Firestore;
+export function getFirestore(): Firestore;
+
+// @public
+export function getFirestore(app: FirebaseApp): Firestore;
+
+// @public
+export function getFirestore(databaseId: string): Firestore;
+
+// @public
+export function getFirestore(app: FirebaseApp, databaseId: string): Firestore;
 
 // @public
 export function increment(n: number): FieldValue;
diff --git a/common/api-review/firestore.api.md b/common/api-review/firestore.api.md
index db36b60482c..f34e846eb7d 100644
--- a/common/api-review/firestore.api.md
+++ b/common/api-review/firestore.api.md
@@ -228,7 +228,16 @@ export function getDocsFromCache<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
 export function getDocsFromServer<T>(query: Query<T>): Promise<QuerySnapshot<T>>;
 
 // @public
-export function getFirestore(app?: FirebaseApp): Firestore;
+export function getFirestore(): Firestore;
+
+// @public
+export function getFirestore(app: FirebaseApp): Firestore;
+
+// @public
+export function getFirestore(databaseId: string): Firestore;
+
+// @public
+export function getFirestore(app: FirebaseApp, databaseId: string): Firestore;
 
 // @public
 export function increment(n: number): FieldValue;
diff --git a/packages/firestore-compat/src/index.console.ts b/packages/firestore-compat/src/index.console.ts
index 7c9a7fc63a2..9adfdefdfd2 100644
--- a/packages/firestore-compat/src/index.console.ts
+++ b/packages/firestore-compat/src/index.console.ts
@@ -91,9 +91,9 @@ export class Firestore extends FirestoreCompat {
     super(
       databaseIdFromFirestoreDatabase(firestoreDatabase),
       new FirestoreExp(
-        databaseIdFromFirestoreDatabase(firestoreDatabase),
         new _EmptyAuthCredentialsProvider(),
-        new _EmptyAppCheckTokenProvider()
+        new _EmptyAppCheckTokenProvider(),
+        databaseIdFromFirestoreDatabase(firestoreDatabase)
       ),
       new MemoryPersistenceProvider()
     );
diff --git a/packages/firestore/lite/register.ts b/packages/firestore/lite/register.ts
index 2ec5f9a3b0e..2afb9bf0f29 100644
--- a/packages/firestore/lite/register.ts
+++ b/packages/firestore/lite/register.ts
@@ -30,6 +30,7 @@ import {
 import { setSDKVersion } from '../src/core/version';
 import { Firestore } from '../src/lite-api/database';
 import { FirestoreSettings } from '../src/lite-api/settings';
+import {databaseIdFromApp} from "../src/core/database_info";
 
 declare module '@firebase/component' {
   interface NameServiceMapping {
@@ -45,13 +46,14 @@ export function registerFirestore(): void {
       (container, { instanceIdentifier: databaseId, options: settings }) => {
         const app = container.getProvider('app').getImmediate()!;
         const firestoreInstance = new Firestore(
-          app,
           new LiteAuthCredentialsProvider(
             container.getProvider('auth-internal')
           ),
           new LiteAppCheckTokenProvider(
             container.getProvider('app-check-internal')
-          )
+          ),
+          databaseIdFromApp(app, databaseId),
+          app,
         );
         if (settings) {
           firestoreInstance._setSettings(settings);
diff --git a/packages/firestore/package.json b/packages/firestore/package.json
index 4f6614d808b..057c6f86f98 100644
--- a/packages/firestore/package.json
+++ b/packages/firestore/package.json
@@ -86,6 +86,7 @@
     "@grpc/grpc-js": "^1.3.2",
     "@grpc/proto-loader": "^0.6.13",
     "node-fetch": "2.6.7",
+    "sqlite3": "^5.0.11",
     "tslib": "^2.1.0"
   },
   "peerDependencies": {
diff --git a/packages/firestore/src/api/database.ts b/packages/firestore/src/api/database.ts
index 9c9ed88ccc2..ba87ee17c9b 100644
--- a/packages/firestore/src/api/database.ts
+++ b/packages/firestore/src/api/database.ts
@@ -103,17 +103,18 @@ export class Firestore extends LiteFirestore {
 
   /** @hideconstructor */
   constructor(
-    databaseIdOrApp: DatabaseId | FirebaseApp,
     authCredentialsProvider: CredentialsProvider<User>,
-    appCheckCredentialsProvider: CredentialsProvider<string>
+    appCheckCredentialsProvider: CredentialsProvider<string>,
+    databaseId: DatabaseId,
+    app?: FirebaseApp
   ) {
     super(
-      databaseIdOrApp,
       authCredentialsProvider,
-      appCheckCredentialsProvider
+      appCheckCredentialsProvider,
+      databaseId,
+      app
     );
-    this._persistenceKey =
-      'name' in databaseIdOrApp ? databaseIdOrApp.name : '[DEFAULT]';
+    this._persistenceKey = app?.name || '[DEFAULT]';
   }
 
   _terminate(): Promise<void> {
@@ -173,6 +174,14 @@ export function initializeFirestore(
   return provider.initialize({ options: settings });
 }
 
+/**
+ * Returns the existing {@link Firestore} instance that is associated with the
+ * default {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
+ * instance with default settings.
+ *
+ * @returns The {@link Firestore} instance of the provided app.
+ */
+export function getFirestore(): Firestore;
 /**
  * Returns the existing {@link Firestore} instance that is associated with the
  * provided {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
@@ -182,12 +191,29 @@ export function initializeFirestore(
  * instance is associated with.
  * @returns The {@link Firestore} instance of the provided app.
  */
+export function getFirestore(app: FirebaseApp): Firestore;
+/**
+ * Returns the existing {@link Firestore} instance that is associated with the
+ * default {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
+ * instance with default settings.
+ *
+ * @param databaseId - The name of database.
+ * @returns The {@link Firestore} instance of the provided app.
+ */
+export function getFirestore(databaseId: string): Firestore;
+/**
+ * Returns the existing {@link Firestore} instance that is associated with the
+ * provided {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
+ * instance with default settings.
+ *
+ * @param app - The {@link @firebase/app#FirebaseApp} instance that the returned {@link Firestore}
+ * instance is associated with.
+ * @param databaseId - The name of database.
+ * @returns The {@link Firestore} instance of the provided app.
+ */
 export function getFirestore(
   app: FirebaseApp,
-  databaseId?: string
-): Firestore;
-export function getFirestore(
-  databaseId?: string
+  databaseId: string
 ): Firestore;
 export function getFirestore(
   appOrDatabaseId?: FirebaseApp | string,
@@ -195,7 +221,7 @@ export function getFirestore(
 ): Firestore {
   const app: FirebaseApp = typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
   const databaseId = typeof appOrDatabaseId === 'string' ? appOrDatabaseId : optionalDatabaseId || '(default)';
-  return _getProvider(app || getApp(), 'firestore').getImmediate({
+  return _getProvider(app, 'firestore').getImmediate({
     identifier: databaseId
   }) as Firestore;
 }
diff --git a/packages/firestore/src/core/database_info.ts b/packages/firestore/src/core/database_info.ts
index c03afb84ac6..4b0e334c5e6 100644
--- a/packages/firestore/src/core/database_info.ts
+++ b/packages/firestore/src/core/database_info.ts
@@ -1,3 +1,6 @@
+import { FirebaseApp } from "@firebase/app";
+import {Code, FirestoreError} from "../util/error";
+
 /**
  * @license
  * Copyright 2017 Google LLC
@@ -74,3 +77,14 @@ export class DatabaseId {
     );
   }
 }
+
+export function databaseIdFromApp(app: FirebaseApp, database?: string): DatabaseId {
+  if (!Object.prototype.hasOwnProperty.apply(app.options, ['projectId'])) {
+    throw new FirestoreError(
+      Code.INVALID_ARGUMENT,
+      '"projectId" not provided in firebase.initializeApp.'
+    );
+  }
+
+  return new DatabaseId(app.options.projectId!, database);
+}
diff --git a/packages/firestore/src/lite-api/database.ts b/packages/firestore/src/lite-api/database.ts
index 07db0a3c868..8d19cfa5fc2 100644
--- a/packages/firestore/src/lite-api/database.ts
+++ b/packages/firestore/src/lite-api/database.ts
@@ -61,7 +61,6 @@ export class Firestore implements FirestoreService {
    */
   type: 'firestore-lite' | 'firestore' = 'firestore-lite';
 
-  readonly _databaseId: DatabaseId;
   readonly _persistenceKey: string = '(lite)';
 
   private _settings = new FirestoreSettingsImpl({});
@@ -71,21 +70,13 @@ export class Firestore implements FirestoreService {
   // all components have shut down.
   private _terminateTask?: Promise<void>;
 
-  _app?: FirebaseApp;
-
   /** @hideconstructor */
   constructor(
-    databaseIdOrApp: DatabaseId | FirebaseApp,
     public _authCredentials: CredentialsProvider<User>,
-    public _appCheckCredentials: CredentialsProvider<string>
-  ) {
-    if (databaseIdOrApp instanceof DatabaseId) {
-      this._databaseId = databaseIdOrApp;
-    } else {
-      this._app = databaseIdOrApp as FirebaseApp;
-      this._databaseId = databaseIdFromApp(databaseIdOrApp as FirebaseApp);
-    }
-  }
+    public _appCheckCredentials: CredentialsProvider<string>,
+    readonly _databaseId: DatabaseId,
+    readonly _app?: FirebaseApp
+  ) {}
 
   /**
    * The {@link @firebase/app#FirebaseApp} associated with this `Firestore` service
@@ -163,17 +154,6 @@ export class Firestore implements FirestoreService {
   }
 }
 
-function databaseIdFromApp(app: FirebaseApp): DatabaseId {
-  if (!Object.prototype.hasOwnProperty.apply(app.options, ['projectId'])) {
-    throw new FirestoreError(
-      Code.INVALID_ARGUMENT,
-      '"projectId" not provided in firebase.initializeApp.'
-    );
-  }
-
-  return new DatabaseId(app.options.projectId!);
-}
-
 /**
  * Initializes a new instance of Cloud Firestore with the provided settings.
  * Can only be called before any other functions, including
@@ -202,16 +182,55 @@ export function initializeFirestore(
 }
 
 /**
- * Returns the existing `Firestore` instance that is associated with the
+ * Returns the existing {@link Firestore} instance that is associated with the
+ * default {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
+ * instance with default settings.
+ *
+ * @returns The {@link Firestore} instance of the provided app.
+ */
+export function getFirestore(): Firestore;
+/**
+ * Returns the existing {@link Firestore} instance that is associated with the
  * provided {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
  * instance with default settings.
  *
- * @param app - The {@link @firebase/app#FirebaseApp} instance that the returned `Firestore`
+ * @param app - The {@link @firebase/app#FirebaseApp} instance that the returned {@link Firestore}
  * instance is associated with.
- * @returns The `Firestore` instance of the provided app.
+ * @returns The {@link Firestore} instance of the provided app.
  */
-export function getFirestore(app: FirebaseApp = getApp()): Firestore {
-  return _getProvider(app, 'firestore/lite').getImmediate() as Firestore;
+export function getFirestore(app: FirebaseApp): Firestore;
+/**
+ * Returns the existing {@link Firestore} instance that is associated with the
+ * default {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
+ * instance with default settings.
+ *
+ * @param databaseId - The name of database.
+ * @returns The {@link Firestore} instance of the provided app.
+ */
+export function getFirestore(databaseId: string): Firestore;
+/**
+ * Returns the existing {@link Firestore} instance that is associated with the
+ * provided {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
+ * instance with default settings.
+ *
+ * @param app - The {@link @firebase/app#FirebaseApp} instance that the returned {@link Firestore}
+ * instance is associated with.
+ * @param databaseId - The name of database.
+ * @returns The {@link Firestore} instance of the provided app.
+ */
+export function getFirestore(
+  app: FirebaseApp,
+  databaseId: string
+): Firestore;
+export function getFirestore(
+  appOrDatabaseId?: FirebaseApp | string,
+  optionalDatabaseId?: string
+): Firestore {
+  const app: FirebaseApp = typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
+  const databaseId = typeof appOrDatabaseId === 'string' ? appOrDatabaseId : optionalDatabaseId || '(default)';
+  return _getProvider(app, 'firestore/lite').getImmediate({
+    identifier: databaseId
+  }) as Firestore;
 }
 
 export { EmulatorMockTokenOptions } from '@firebase/util';
diff --git a/packages/firestore/src/register.ts b/packages/firestore/src/register.ts
index 1bcda165648..01c95477fb1 100644
--- a/packages/firestore/src/register.ts
+++ b/packages/firestore/src/register.ts
@@ -31,6 +31,7 @@ import { setSDKVersion } from '../src/core/version';
 
 import { Firestore } from './api/database';
 import { PrivateSettings } from './lite-api/settings';
+import {databaseIdFromApp} from "./core/database_info";
 
 export function registerFirestore(
   variant?: string,
@@ -43,13 +44,14 @@ export function registerFirestore(
       (container, { instanceIdentifier: databaseId, options: settings }) => {
         const app = container.getProvider('app').getImmediate()!;
         const firestoreInstance = new Firestore(
-          app,
           new FirebaseAuthCredentialsProvider(
             container.getProvider('auth-internal')
           ),
           new FirebaseAppCheckTokenProvider(
             container.getProvider('app-check-internal')
-          )
+          ),
+          databaseIdFromApp(app, databaseId),
+          app,
         );
         settings = { useFetchStreams, ...settings };
         firestoreInstance._setSettings(settings);
diff --git a/packages/firestore/test/lite/integration.test.ts b/packages/firestore/test/lite/integration.test.ts
index deaa9a0236f..ae1f21ff9e7 100644
--- a/packages/firestore/test/lite/integration.test.ts
+++ b/packages/firestore/test/lite/integration.test.ts
@@ -96,7 +96,7 @@ import {
 
 use(chaiAsPromised);
 
-describe('Firestore', () => {
+describe.only('Firestore', () => {
   it('can provide setting', () => {
     const app = initializeApp(
       { apiKey: 'fake-api-key', projectId: 'test-project' },
@@ -106,14 +106,57 @@ describe('Firestore', () => {
     expect(fs1).to.be.an.instanceOf(Firestore);
   });
 
-  it('returns same instance', () => {
+  it('returns same default instance from named app', () => {
     const app = initializeApp(
       { apiKey: 'fake-api-key', projectId: 'test-project' },
       'test-app-getFirestore'
     );
     const fs1 = getFirestore(app);
     const fs2 = getFirestore(app);
-    expect(fs1 === fs2).to.be.true;
+    const fs3 = getFirestore(app, '(default)');
+    expect(fs1).to.be.equal(fs2).and.equal(fs3);
+  });
+
+  it('returns different instance from named app', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore'
+    );
+    const fs1 = getFirestore(app);
+    const fs2 = getFirestore(app, 'name1');
+    const fs3 = getFirestore(app, 'name2');
+    expect(fs1).to.not.be.equal(fs2).and.equal(fs3);
+    expect(fs2).to.not.be.equal(fs3);
+  });
+
+  it('returns same default instance from default app', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' }
+    );
+    const fs1 = getFirestore();
+    const fs2 = getFirestore(app);
+    const fs3 = getFirestore( '(default)');
+    const fs4 = getFirestore(app, '(default)');
+    expect(fs1).to.be.equal(fs2).and.equal(fs3).and.equal(fs4);
+  });
+
+  it('returns different instance from different named app', () => {
+    initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+    );
+    const app1 = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore-1'
+    );
+    const app2 = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore-2'
+    );
+    const fs1 = getFirestore();
+    const fs2 = getFirestore(app1);
+    const fs3 = getFirestore(app2);
+    expect(fs1).to.not.be.equal(fs2).and.equal(fs3);
+    expect(fs2).to.not.be.equal(fs3);
   });
 
   it('cannot call initializeFirestore() twice', () => {
diff --git a/packages/firestore/test/util/api_helpers.ts b/packages/firestore/test/util/api_helpers.ts
index 81d01132087..2dd8a6199e0 100644
--- a/packages/firestore/test/util/api_helpers.ts
+++ b/packages/firestore/test/util/api_helpers.ts
@@ -58,9 +58,9 @@ export function firestore(): Firestore {
 
 export function newTestFirestore(projectId = 'new-project'): Firestore {
   return new Firestore(
-    new DatabaseId(projectId),
     new EmptyAuthCredentialsProvider(),
-    new EmptyAppCheckTokenProvider()
+    new EmptyAppCheckTokenProvider(),
+    new DatabaseId(projectId)
   );
 }
 

From 1546ce6b70bcc9fe9619c9f6e8585ac4b1cdcf26 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Mon, 8 Aug 2022 15:57:17 -0400
Subject: [PATCH 04/16] Fix linting

---
 packages/firestore/lite/register.ts              | 10 ++++++----
 packages/firestore/src/api/database.ts           | 13 +++++++------
 packages/firestore/src/core/database_info.ts     | 10 +++++++---
 packages/firestore/src/lite-api/database.ts      | 13 +++++++------
 packages/firestore/src/register.ts               |  5 ++---
 packages/firestore/test/lite/integration.test.ts | 15 +++++++--------
 6 files changed, 36 insertions(+), 30 deletions(-)

diff --git a/packages/firestore/lite/register.ts b/packages/firestore/lite/register.ts
index 2afb9bf0f29..a32bf761901 100644
--- a/packages/firestore/lite/register.ts
+++ b/packages/firestore/lite/register.ts
@@ -20,17 +20,19 @@ import {
   registerVersion,
   SDK_VERSION
 } from '@firebase/app';
-import { Component, ComponentType, InstanceFactoryOptions } from '@firebase/component';
+import {
+  Component,
+  ComponentType
+} from '@firebase/component';
 
 import { version } from '../package.json';
 import {
   LiteAppCheckTokenProvider,
   LiteAuthCredentialsProvider
 } from '../src/api/credentials';
+import { databaseIdFromApp } from '../src/core/database_info';
 import { setSDKVersion } from '../src/core/version';
 import { Firestore } from '../src/lite-api/database';
-import { FirestoreSettings } from '../src/lite-api/settings';
-import {databaseIdFromApp} from "../src/core/database_info";
 
 declare module '@firebase/component' {
   interface NameServiceMapping {
@@ -53,7 +55,7 @@ export function registerFirestore(): void {
             container.getProvider('app-check-internal')
           ),
           databaseIdFromApp(app, databaseId),
-          app,
+          app
         );
         if (settings) {
           firestoreInstance._setSettings(settings);
diff --git a/packages/firestore/src/api/database.ts b/packages/firestore/src/api/database.ts
index ba87ee17c9b..5ad4b2ae465 100644
--- a/packages/firestore/src/api/database.ts
+++ b/packages/firestore/src/api/database.ts
@@ -211,16 +211,17 @@ export function getFirestore(databaseId: string): Firestore;
  * @param databaseId - The name of database.
  * @returns The {@link Firestore} instance of the provided app.
  */
-export function getFirestore(
-  app: FirebaseApp,
-  databaseId: string
-): Firestore;
+export function getFirestore(app: FirebaseApp, databaseId: string): Firestore;
 export function getFirestore(
   appOrDatabaseId?: FirebaseApp | string,
   optionalDatabaseId?: string
 ): Firestore {
-  const app: FirebaseApp = typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
-  const databaseId = typeof appOrDatabaseId === 'string' ? appOrDatabaseId : optionalDatabaseId || '(default)';
+  const app: FirebaseApp =
+    typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
+  const databaseId =
+    typeof appOrDatabaseId === 'string'
+      ? appOrDatabaseId
+      : optionalDatabaseId || '(default)';
   return _getProvider(app, 'firestore').getImmediate({
     identifier: databaseId
   }) as Firestore;
diff --git a/packages/firestore/src/core/database_info.ts b/packages/firestore/src/core/database_info.ts
index 4b0e334c5e6..1bee1c0c1c8 100644
--- a/packages/firestore/src/core/database_info.ts
+++ b/packages/firestore/src/core/database_info.ts
@@ -1,5 +1,6 @@
-import { FirebaseApp } from "@firebase/app";
-import {Code, FirestoreError} from "../util/error";
+import { FirebaseApp } from '@firebase/app';
+
+import { Code, FirestoreError } from '../util/error';
 
 /**
  * @license
@@ -78,7 +79,10 @@ export class DatabaseId {
   }
 }
 
-export function databaseIdFromApp(app: FirebaseApp, database?: string): DatabaseId {
+export function databaseIdFromApp(
+  app: FirebaseApp,
+  database?: string
+): DatabaseId {
   if (!Object.prototype.hasOwnProperty.apply(app.options, ['projectId'])) {
     throw new FirestoreError(
       Code.INVALID_ARGUMENT,
diff --git a/packages/firestore/src/lite-api/database.ts b/packages/firestore/src/lite-api/database.ts
index 8d19cfa5fc2..3d2b4fb0026 100644
--- a/packages/firestore/src/lite-api/database.ts
+++ b/packages/firestore/src/lite-api/database.ts
@@ -218,16 +218,17 @@ export function getFirestore(databaseId: string): Firestore;
  * @param databaseId - The name of database.
  * @returns The {@link Firestore} instance of the provided app.
  */
-export function getFirestore(
-  app: FirebaseApp,
-  databaseId: string
-): Firestore;
+export function getFirestore(app: FirebaseApp, databaseId: string): Firestore;
 export function getFirestore(
   appOrDatabaseId?: FirebaseApp | string,
   optionalDatabaseId?: string
 ): Firestore {
-  const app: FirebaseApp = typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
-  const databaseId = typeof appOrDatabaseId === 'string' ? appOrDatabaseId : optionalDatabaseId || '(default)';
+  const app: FirebaseApp =
+    typeof appOrDatabaseId === 'object' ? appOrDatabaseId : getApp();
+  const databaseId =
+    typeof appOrDatabaseId === 'string'
+      ? appOrDatabaseId
+      : optionalDatabaseId || '(default)';
   return _getProvider(app, 'firestore/lite').getImmediate({
     identifier: databaseId
   }) as Firestore;
diff --git a/packages/firestore/src/register.ts b/packages/firestore/src/register.ts
index 01c95477fb1..84ecc3d9746 100644
--- a/packages/firestore/src/register.ts
+++ b/packages/firestore/src/register.ts
@@ -30,8 +30,7 @@ import {
 import { setSDKVersion } from '../src/core/version';
 
 import { Firestore } from './api/database';
-import { PrivateSettings } from './lite-api/settings';
-import {databaseIdFromApp} from "./core/database_info";
+import { databaseIdFromApp } from './core/database_info';
 
 export function registerFirestore(
   variant?: string,
@@ -51,7 +50,7 @@ export function registerFirestore(
             container.getProvider('app-check-internal')
           ),
           databaseIdFromApp(app, databaseId),
-          app,
+          app
         );
         settings = { useFetchStreams, ...settings };
         firestoreInstance._setSettings(settings);
diff --git a/packages/firestore/test/lite/integration.test.ts b/packages/firestore/test/lite/integration.test.ts
index ae1f21ff9e7..e82458071a7 100644
--- a/packages/firestore/test/lite/integration.test.ts
+++ b/packages/firestore/test/lite/integration.test.ts
@@ -96,7 +96,7 @@ import {
 
 use(chaiAsPromised);
 
-describe.only('Firestore', () => {
+describe('Firestore', () => {
   it('can provide setting', () => {
     const app = initializeApp(
       { apiKey: 'fake-api-key', projectId: 'test-project' },
@@ -130,20 +130,19 @@ describe.only('Firestore', () => {
   });
 
   it('returns same default instance from default app', () => {
-    const app = initializeApp(
-      { apiKey: 'fake-api-key', projectId: 'test-project' }
-    );
+    const app = initializeApp({
+      apiKey: 'fake-api-key',
+      projectId: 'test-project'
+    });
     const fs1 = getFirestore();
     const fs2 = getFirestore(app);
-    const fs3 = getFirestore( '(default)');
+    const fs3 = getFirestore('(default)');
     const fs4 = getFirestore(app, '(default)');
     expect(fs1).to.be.equal(fs2).and.equal(fs3).and.equal(fs4);
   });
 
   it('returns different instance from different named app', () => {
-    initializeApp(
-      { apiKey: 'fake-api-key', projectId: 'test-project' },
-    );
+    initializeApp({ apiKey: 'fake-api-key', projectId: 'test-project' });
     const app1 = initializeApp(
       { apiKey: 'fake-api-key', projectId: 'test-project' },
       'test-app-getFirestore-1'

From 36b774ff5ea1bd919972f7f1856b5d5ae216cfa0 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Mon, 8 Aug 2022 16:05:53 -0400
Subject: [PATCH 05/16] Fix linting

---
 packages/firestore/lite/register.ts | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/packages/firestore/lite/register.ts b/packages/firestore/lite/register.ts
index a32bf761901..9bd7b014fa2 100644
--- a/packages/firestore/lite/register.ts
+++ b/packages/firestore/lite/register.ts
@@ -20,10 +20,7 @@ import {
   registerVersion,
   SDK_VERSION
 } from '@firebase/app';
-import {
-  Component,
-  ComponentType
-} from '@firebase/component';
+import { Component, ComponentType } from '@firebase/component';
 
 import { version } from '../package.json';
 import {

From 21be3483558630ee8abc4fd22723c6a015635545 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Mon, 8 Aug 2022 16:18:32 -0400
Subject: [PATCH 06/16] Undo package.json change.

---
 packages/firestore/package.json | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/firestore/package.json b/packages/firestore/package.json
index 057c6f86f98..4f6614d808b 100644
--- a/packages/firestore/package.json
+++ b/packages/firestore/package.json
@@ -86,7 +86,6 @@
     "@grpc/grpc-js": "^1.3.2",
     "@grpc/proto-loader": "^0.6.13",
     "node-fetch": "2.6.7",
-    "sqlite3": "^5.0.11",
     "tslib": "^2.1.0"
   },
   "peerDependencies": {

From 3aaa0ea5f7a6ab25380d6ec9d42f8dd6868b8ed4 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Tue, 9 Aug 2022 10:23:19 -0400
Subject: [PATCH 07/16] Changset for Multi-DB support

---
 .changeset/heavy-spiders-fry.md | 6 ++++++
 1 file changed, 6 insertions(+)
 create mode 100644 .changeset/heavy-spiders-fry.md

diff --git a/.changeset/heavy-spiders-fry.md b/.changeset/heavy-spiders-fry.md
new file mode 100644
index 00000000000..f10664373c2
--- /dev/null
+++ b/.changeset/heavy-spiders-fry.md
@@ -0,0 +1,6 @@
+---
+'@firebase/firestore': minor
+'@firebase/firestore-compat': patch
+---
+
+Add named DB support

From 79e31d02b868eef18b1f1819e2e5aa46ba89063e Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Wed, 10 Aug 2022 21:17:21 -0400
Subject: [PATCH 08/16] Add more multi-db tests, and fix a few bugs related to
 multi-db.

---
 packages/firestore/src/api/database.ts        |  36 ++--
 packages/firestore/src/core/database_info.ts  |   2 +-
 packages/firestore/src/lite-api/database.ts   |  20 ++-
 packages/firestore/src/register.ts            |   2 +-
 .../test/integration/api/database.test.ts     |  64 ++++++-
 .../test/integration/api/provider.test.ts     | 161 ++++++++++++++++++
 .../test/integration/api/validation.test.ts   |  13 +-
 .../test/integration/util/firebase_export.ts  |  36 ++--
 .../test/integration/util/helpers.ts          |  32 +++-
 .../firestore/test/lite/integration.test.ts   |  35 ++--
 10 files changed, 339 insertions(+), 62 deletions(-)
 create mode 100644 packages/firestore/test/integration/api/provider.test.ts

diff --git a/packages/firestore/src/api/database.ts b/packages/firestore/src/api/database.ts
index 5ad4b2ae465..5194cfcd462 100644
--- a/packages/firestore/src/api/database.ts
+++ b/packages/firestore/src/api/database.ts
@@ -31,7 +31,7 @@ import {
   OfflineComponentProvider,
   OnlineComponentProvider
 } from '../core/component_provider';
-import { DatabaseId } from '../core/database_info';
+import { DatabaseId, DEFAULT_DATABASE_NAME } from '../core/database_info';
 import {
   FirestoreClient,
   firestoreClientDisableNetwork,
@@ -136,17 +136,26 @@ export class Firestore extends LiteFirestore {
  * @param app - The {@link @firebase/app#FirebaseApp} with which the {@link Firestore} instance will
  * be associated.
  * @param settings - A settings object to configure the {@link Firestore} instance.
+ * @param databaseId - The name of database.
  * @returns A newly initialized {@link Firestore} instance.
  */
 export function initializeFirestore(
   app: FirebaseApp,
-  settings: FirestoreSettings
+  settings: FirestoreSettings,
+  databaseId?: string
 ): Firestore {
+  if (!databaseId) {
+    databaseId = DEFAULT_DATABASE_NAME;
+  }
   const provider = _getProvider(app, 'firestore');
 
-  if (provider.isInitialized()) {
-    const existingInstance = provider.getImmediate();
-    const initialSettings = provider.getOptions() as FirestoreSettings;
+  if (provider.isInitialized(databaseId)) {
+    const existingInstance = provider.getImmediate({
+      identifier: databaseId
+    });
+    const initialSettings = provider.getOptions(
+      databaseId
+    ) as FirestoreSettings;
     if (deepEqual(initialSettings, settings)) {
       return existingInstance;
     } else {
@@ -171,11 +180,14 @@ export function initializeFirestore(
     );
   }
 
-  return provider.initialize({ options: settings });
+  return provider.initialize({
+    options: settings,
+    instanceIdentifier: databaseId
+  });
 }
 
 /**
- * Returns the existing {@link Firestore} instance that is associated with the
+ * Returns the existing default {@link Firestore} instance that is associated with the
  * default {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
  * instance with default settings.
  *
@@ -183,7 +195,7 @@ export function initializeFirestore(
  */
 export function getFirestore(): Firestore;
 /**
- * Returns the existing {@link Firestore} instance that is associated with the
+ * Returns the existing default {@link Firestore} instance that is associated with the
  * provided {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
  * instance with default settings.
  *
@@ -221,7 +233,7 @@ export function getFirestore(
   const databaseId =
     typeof appOrDatabaseId === 'string'
       ? appOrDatabaseId
-      : optionalDatabaseId || '(default)';
+      : optionalDatabaseId || DEFAULT_DATABASE_NAME;
   return _getProvider(app, 'firestore').getImmediate({
     identifier: databaseId
   }) as Firestore;
@@ -539,7 +551,11 @@ export function disableNetwork(firestore: Firestore): Promise<void> {
  * terminated.
  */
 export function terminate(firestore: Firestore): Promise<void> {
-  _removeServiceInstance(firestore.app, 'firestore');
+  _removeServiceInstance(
+    firestore.app,
+    'firestore',
+    firestore._databaseId.database
+  );
   return firestore._delete();
 }
 
diff --git a/packages/firestore/src/core/database_info.ts b/packages/firestore/src/core/database_info.ts
index 1bee1c0c1c8..306a9920ea9 100644
--- a/packages/firestore/src/core/database_info.ts
+++ b/packages/firestore/src/core/database_info.ts
@@ -50,7 +50,7 @@ export class DatabaseInfo {
 }
 
 /** The default database name for a project. */
-const DEFAULT_DATABASE_NAME = '(default)';
+export const DEFAULT_DATABASE_NAME = '(default)';
 
 /**
  * Represents the database ID a Firestore client is associated with.
diff --git a/packages/firestore/src/lite-api/database.ts b/packages/firestore/src/lite-api/database.ts
index 3d2b4fb0026..8cfd6577943 100644
--- a/packages/firestore/src/lite-api/database.ts
+++ b/packages/firestore/src/lite-api/database.ts
@@ -31,7 +31,7 @@ import {
   OAuthToken
 } from '../api/credentials';
 import { User } from '../auth/user';
-import { DatabaseId } from '../core/database_info';
+import { DatabaseId, DEFAULT_DATABASE_NAME } from '../core/database_info';
 import { Code, FirestoreError } from '../util/error';
 import { cast } from '../util/input_validation';
 import { logWarn } from '../util/log';
@@ -163,26 +163,34 @@ export class Firestore implements FirestoreService {
  * @param app - The {@link @firebase/app#FirebaseApp} with which the `Firestore` instance will
  * be associated.
  * @param settings - A settings object to configure the `Firestore` instance.
+ * @param databaseId - The name of database.
  * @returns A newly initialized `Firestore` instance.
  */
 export function initializeFirestore(
   app: FirebaseApp,
-  settings: FirestoreSettings
+  settings: FirestoreSettings,
+  databaseId?: string
 ): Firestore {
+  if (!databaseId) {
+    databaseId = DEFAULT_DATABASE_NAME;
+  }
   const provider = _getProvider(app, 'firestore/lite');
 
-  if (provider.isInitialized()) {
+  if (provider.isInitialized(databaseId)) {
     throw new FirestoreError(
       Code.FAILED_PRECONDITION,
       'Firestore can only be initialized once per app.'
     );
   }
 
-  return provider.initialize({ options: settings });
+  return provider.initialize({
+    options: settings,
+    instanceIdentifier: databaseId
+  });
 }
 
 /**
- * Returns the existing {@link Firestore} instance that is associated with the
+ * Returns the existing default {@link Firestore} instance that is associated with the
  * default {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
  * instance with default settings.
  *
@@ -190,7 +198,7 @@ export function initializeFirestore(
  */
 export function getFirestore(): Firestore;
 /**
- * Returns the existing {@link Firestore} instance that is associated with the
+ * Returns the existing default {@link Firestore} instance that is associated with the
  * provided {@link @firebase/app#FirebaseApp}. If no instance exists, initializes a new
  * instance with default settings.
  *
diff --git a/packages/firestore/src/register.ts b/packages/firestore/src/register.ts
index 84ecc3d9746..3abb38c9d86 100644
--- a/packages/firestore/src/register.ts
+++ b/packages/firestore/src/register.ts
@@ -57,7 +57,7 @@ export function registerFirestore(
         return firestoreInstance;
       },
       'PUBLIC' as ComponentType.PUBLIC
-    )
+    ).setMultipleInstances(true)
   );
   registerVersion(name, version, variant);
   // BUILD_TARGET will be replaced by values like esm5, esm2017, cjs5, etc during the compilation
diff --git a/packages/firestore/test/integration/api/database.test.ts b/packages/firestore/test/integration/api/database.test.ts
index 5609d86a8b4..c39162ba858 100644
--- a/packages/firestore/test/integration/api/database.test.ts
+++ b/packages/firestore/test/integration/api/database.test.ts
@@ -62,7 +62,8 @@ import {
   Timestamp,
   FieldPath,
   newTestFirestore,
-  SnapshotOptions
+  SnapshotOptions,
+  newTestApp
 } from '../util/firebase_export';
 import {
   apiDescribe,
@@ -71,7 +72,8 @@ import {
   withTestDb,
   withTestDbs,
   withTestDoc,
-  withTestDocAndInitialData
+  withTestDocAndInitialData,
+  withNamedTestDbs
 } from '../util/helpers';
 import { DEFAULT_SETTINGS, DEFAULT_PROJECT_ID } from '../util/settings';
 
@@ -1106,8 +1108,7 @@ apiDescribe('Database', (persistence: boolean) => {
       await deleteApp(app);
 
       const firestore2 = newTestFirestore(
-        options.projectId!,
-        name,
+        newTestApp(options.projectId!, name),
         DEFAULT_SETTINGS
       );
       await enableIndexedDbPersistence(firestore2);
@@ -1149,7 +1150,9 @@ apiDescribe('Database', (persistence: boolean) => {
 
         await deleteApp(app);
 
-        const firestore2 = newTestFirestore(options.projectId!, name);
+        const firestore2 = newTestFirestore(
+          newTestApp(options.projectId!, name)
+        );
         await enableIndexedDbPersistence(firestore2);
         const docRef2 = doc(firestore2, docRef.path);
         const docSnap2 = await getDocFromCache(docRef2);
@@ -1170,7 +1173,9 @@ apiDescribe('Database', (persistence: boolean) => {
 
         await deleteApp(app);
         await clearIndexedDbPersistence(firestore);
-        const firestore2 = newTestFirestore(options.projectId!, name);
+        const firestore2 = newTestFirestore(
+          newTestApp(options.projectId!, name)
+        );
         await enableIndexedDbPersistence(firestore2);
         const docRef2 = doc(firestore2, docRef.path);
         await expect(getDocFromCache(docRef2)).to.eventually.be.rejectedWith(
@@ -1191,7 +1196,9 @@ apiDescribe('Database', (persistence: boolean) => {
         const options = app.options;
 
         await deleteApp(app);
-        const firestore2 = newTestFirestore(options.projectId!, name);
+        const firestore2 = newTestFirestore(
+          newTestApp(options.projectId!, name)
+        );
         await clearIndexedDbPersistence(firestore2);
         await enableIndexedDbPersistence(firestore2);
         const docRef2 = doc(firestore2, docRef.path);
@@ -1701,4 +1708,47 @@ apiDescribe('Database', (persistence: boolean) => {
       }
     );
   });
+
+  it('can keep docs separate with multi-db when online', () => {
+    return withNamedTestDbs(
+      persistence,
+      ['db1', 'db2', 'db1'],
+      async ([db1, db2]) => {
+        const data = { name: 'Rafi', email: 'abc@xyz.com' };
+
+        const ref1 = await doc(collection(db1, 'users'));
+        await setDoc(ref1, data);
+        const snapshot1 = await getDoc(ref1);
+        expect(snapshot1.exists()).to.be.ok;
+        expect(snapshot1.data()).to.be.deep.equals(data);
+
+        const ref2 = await doc(collection(db2, 'users'));
+        const snapshot2 = await getDoc(ref2);
+        expect(snapshot2.exists()).to.not.be.ok;
+      }
+    );
+  });
+
+  it('can keep docs separate with multi-db when offline', () => {
+    return withNamedTestDbs(
+      persistence,
+      ['db1', 'db2', 'db1'],
+      async ([db1, db2]) => {
+        await disableNetwork(db1);
+        await disableNetwork(db2);
+        const data = { name: 'Rafi', email: 'abc@xyz.com' };
+
+        const ref1 = await doc(collection(db1, 'users'));
+        void setDoc(ref1, data);
+        const snapshot = await getDocFromCache(ref1);
+        expect(snapshot.exists()).to.be.ok;
+        expect(snapshot.data()).to.be.deep.equals(data);
+
+        const ref2 = await doc(collection(db2, 'users'));
+        await expect(getDocFromCache(ref2)).to.eventually.rejectedWith(
+          'Failed to get document from cache.'
+        );
+      }
+    );
+  });
 });
diff --git a/packages/firestore/test/integration/api/provider.test.ts b/packages/firestore/test/integration/api/provider.test.ts
new file mode 100644
index 00000000000..abcf2bc22b0
--- /dev/null
+++ b/packages/firestore/test/integration/api/provider.test.ts
@@ -0,0 +1,161 @@
+/**
+ * @license
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { initializeApp } from '@firebase/app';
+import { expect, use } from 'chai';
+import chaiAsPromised from 'chai-as-promised';
+
+import {
+  doc,
+  getFirestore,
+  initializeFirestore,
+  Firestore,
+  terminate,
+  getDoc
+} from '../../../src';
+import { DEFAULT_SETTINGS } from '../util/settings';
+
+use(chaiAsPromised);
+
+describe('Firestore Provider', () => {
+  it('can provide setting', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-initializeFirestore'
+    );
+    const fs1 = initializeFirestore(app, { host: 'localhost', ssl: false });
+    expect(fs1).to.be.an.instanceOf(Firestore);
+  });
+
+  it('returns same default instance from named app', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore'
+    );
+    const fs1 = getFirestore(app);
+    const fs2 = getFirestore(app);
+    const fs3 = getFirestore(app, '(default)');
+    expect(fs1).to.be.equal(fs2).and.equal(fs3);
+  });
+
+  it('returns different instance from named app', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore'
+    );
+    const fs1 = initializeFirestore(app, DEFAULT_SETTINGS, 'init1');
+    const fs2 = initializeFirestore(app, DEFAULT_SETTINGS, 'init2');
+    const fs3 = getFirestore(app);
+    const fs4 = getFirestore(app, 'name1');
+    const fs5 = getFirestore(app, 'name2');
+    expect(fs1).to.not.be.equal(fs2);
+    expect(fs1).to.not.be.equal(fs3);
+    expect(fs1).to.not.be.equal(fs4);
+    expect(fs1).to.not.be.equal(fs5);
+    expect(fs2).to.not.be.equal(fs3);
+    expect(fs2).to.not.be.equal(fs4);
+    expect(fs2).to.not.be.equal(fs5);
+    expect(fs3).to.not.be.equal(fs4);
+    expect(fs3).to.not.be.equal(fs5);
+    expect(fs4).to.not.be.equal(fs5);
+  });
+
+  it('returns same default instance from default app', () => {
+    const app = initializeApp({
+      apiKey: 'fake-api-key',
+      projectId: 'test-project'
+    });
+    const fs1 = initializeFirestore(app, DEFAULT_SETTINGS);
+    const fs2 = initializeFirestore(app, DEFAULT_SETTINGS);
+    const fs3 = getFirestore();
+    const fs4 = getFirestore(app);
+    const fs5 = getFirestore('(default)');
+    const fs6 = getFirestore(app, '(default)');
+    expect(fs1).to.be.equal(fs2);
+    expect(fs1).to.be.equal(fs3);
+    expect(fs1).to.be.equal(fs4);
+    expect(fs1).to.be.equal(fs5);
+    expect(fs1).to.be.equal(fs6);
+  });
+
+  it('returns different instance from different named app', () => {
+    initializeApp({ apiKey: 'fake-api-key', projectId: 'test-project' });
+    const app1 = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore-1'
+    );
+    const app2 = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-getFirestore-2'
+    );
+    const fs1 = getFirestore();
+    const fs2 = getFirestore(app1);
+    const fs3 = getFirestore(app2);
+    expect(fs1).to.not.be.equal(fs2);
+    expect(fs1).to.not.be.equal(fs3);
+    expect(fs2).to.not.be.equal(fs3);
+  });
+
+  it('can call initializeFirestore() twice if settings are same', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-initializeFirestore-twice'
+    );
+    const fs1 = initializeFirestore(app, DEFAULT_SETTINGS);
+    const fs2 = initializeFirestore(app, DEFAULT_SETTINGS);
+    expect(fs1).to.be.equal(fs2);
+  });
+
+  it('cannot use once terminated', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-terminated'
+    );
+    const firestore = initializeFirestore(app, {
+      host: 'localhost',
+      ssl: false
+    });
+
+    // We don't await the Promise. Any operation enqueued after should be
+    // rejected.
+    // eslint-disable-next-line @typescript-eslint/no-floating-promises
+    terminate(firestore);
+
+    try {
+      // eslint-disable-next-line @typescript-eslint/no-floating-promises
+      getDoc(doc(firestore, 'coll/doc'));
+      expect.fail();
+    } catch (e) {
+      expect((e as Error)?.message).to.equal(
+        'The client has already been terminated.'
+      );
+    }
+  });
+
+  it('can call terminate() multiple times', () => {
+    const app = initializeApp(
+      { apiKey: 'fake-api-key', projectId: 'test-project' },
+      'test-app-multi-terminate'
+    );
+    const firestore = initializeFirestore(app, {
+      host: 'localhost',
+      ssl: false
+    });
+
+    return terminate(firestore).then(() => terminate(firestore));
+  });
+});
diff --git a/packages/firestore/test/integration/api/validation.test.ts b/packages/firestore/test/integration/api/validation.test.ts
index a61b5595ec0..2943a8b0c06 100644
--- a/packages/firestore/test/integration/api/validation.test.ts
+++ b/packages/firestore/test/integration/api/validation.test.ts
@@ -49,7 +49,8 @@ import {
   serverTimestamp,
   setDoc,
   updateDoc,
-  where
+  where,
+  newTestApp
 } from '../util/firebase_export';
 import {
   apiDescribe,
@@ -156,19 +157,19 @@ apiDescribe('Validation:', (persistence: boolean) => {
 
     validationIt(persistence, 'enforces minimum cache size', () => {
       expect(() =>
-        newTestFirestore('test-project', undefined, { cacheSizeBytes: 1 })
+        newTestFirestore(newTestApp('test-project'), { cacheSizeBytes: 1 })
       ).to.throw('cacheSizeBytes must be at least 1048576');
     });
 
     validationIt(persistence, 'garbage collection can be disabled', () => {
       // Verify that this doesn't throw.
-      newTestFirestore('test-project', undefined, {
+      newTestFirestore(newTestApp('test-project'), {
         cacheSizeBytes: /* CACHE_SIZE_UNLIMITED= */ -1
       });
     });
 
     validationIt(persistence, 'useEmulator can set host and port', () => {
-      const db = newTestFirestore('test-project');
+      const db = newTestFirestore(newTestApp('test-project'));
       // Verify that this doesn't throw.
       connectFirestoreEmulator(db, 'localhost', 9000);
     });
@@ -191,7 +192,7 @@ apiDescribe('Validation:', (persistence: boolean) => {
       persistence,
       'useEmulator can set mockUserToken object',
       () => {
-        const db = newTestFirestore('test-project');
+        const db = newTestFirestore(newTestApp('test-project'));
         // Verify that this doesn't throw.
         connectFirestoreEmulator(db, 'localhost', 9000, {
           mockUserToken: { sub: 'foo' }
@@ -203,7 +204,7 @@ apiDescribe('Validation:', (persistence: boolean) => {
       persistence,
       'useEmulator can set mockUserToken string',
       () => {
-        const db = newTestFirestore('test-project');
+        const db = newTestFirestore(newTestApp('test-project'));
         // Verify that this doesn't throw.
         connectFirestoreEmulator(db, 'localhost', 9000, {
           mockUserToken: 'my-mock-user-token'
diff --git a/packages/firestore/test/integration/util/firebase_export.ts b/packages/firestore/test/integration/util/firebase_export.ts
index ab52cb2e1db..f58b3ce045b 100644
--- a/packages/firestore/test/integration/util/firebase_export.ts
+++ b/packages/firestore/test/integration/util/firebase_export.ts
@@ -29,27 +29,25 @@ import { PrivateSettings } from '../../../src/lite-api/settings';
 // every test and never clean them up. We may need to revisit.
 let appCount = 0;
 
-export function newTestFirestore(
-  projectId: string,
-  nameOrApp?: string | FirebaseApp,
-  settings?: PrivateSettings
-): Firestore {
-  if (nameOrApp === undefined) {
-    nameOrApp = 'test-app-' + appCount++;
+export function newTestApp(projectId: string, appName?: string): FirebaseApp {
+  if (appName === undefined) {
+    appName = 'test-app-' + appCount++;
   }
+  return initializeApp(
+    {
+      apiKey: 'fake-api-key',
+      projectId
+    },
+    appName
+  );
+}
 
-  const app =
-    typeof nameOrApp === 'string'
-      ? initializeApp(
-          {
-            apiKey: 'fake-api-key',
-            projectId
-          },
-          nameOrApp
-        )
-      : nameOrApp;
-
-  return initializeFirestore(app, settings || {});
+export function newTestFirestore(
+  app: FirebaseApp,
+  settings?: PrivateSettings,
+  dbName?: string
+): Firestore {
+  return initializeFirestore(app, settings || {}, dbName);
 }
 
 export * from '../../../src';
diff --git a/packages/firestore/test/integration/util/helpers.ts b/packages/firestore/test/integration/util/helpers.ts
index 0a8dd3a5108..9f778e00ebd 100644
--- a/packages/firestore/test/integration/util/helpers.ts
+++ b/packages/firestore/test/integration/util/helpers.ts
@@ -31,7 +31,8 @@ import {
   setDoc,
   PrivateSettings,
   SnapshotListenOptions,
-  newTestFirestore
+  newTestFirestore,
+  newTestApp
 } from './firebase_export';
 import {
   ALT_PROJECT_ID,
@@ -182,7 +183,34 @@ export async function withTestDbsSettings(
   const dbs: Firestore[] = [];
 
   for (let i = 0; i < numDbs; i++) {
-    const db = newTestFirestore(projectId, /* name =*/ undefined, settings);
+    const db = newTestFirestore(newTestApp(projectId), settings);
+    if (persistence) {
+      await enableIndexedDbPersistence(db);
+    }
+    dbs.push(db);
+  }
+
+  try {
+    await fn(dbs);
+  } finally {
+    for (const db of dbs) {
+      await terminate(db);
+      if (persistence) {
+        await clearIndexedDbPersistence(db);
+      }
+    }
+  }
+}
+
+export async function withNamedTestDbs(
+  persistence: boolean,
+  dbNames: string[],
+  fn: (db: Firestore[]) => Promise<void>
+): Promise<void> {
+  const app = newTestApp(DEFAULT_PROJECT_ID);
+  const dbs: Firestore[] = [];
+  for (const dbName of dbNames) {
+    const db = newTestFirestore(app, DEFAULT_SETTINGS, dbName);
     if (persistence) {
       await enableIndexedDbPersistence(db);
     }
diff --git a/packages/firestore/test/lite/integration.test.ts b/packages/firestore/test/lite/integration.test.ts
index e82458071a7..262a0489b05 100644
--- a/packages/firestore/test/lite/integration.test.ts
+++ b/packages/firestore/test/lite/integration.test.ts
@@ -122,11 +122,21 @@ describe('Firestore', () => {
       { apiKey: 'fake-api-key', projectId: 'test-project' },
       'test-app-getFirestore'
     );
-    const fs1 = getFirestore(app);
-    const fs2 = getFirestore(app, 'name1');
-    const fs3 = getFirestore(app, 'name2');
-    expect(fs1).to.not.be.equal(fs2).and.equal(fs3);
+    const fs1 = initializeFirestore(app, DEFAULT_SETTINGS, 'init1');
+    const fs2 = initializeFirestore(app, DEFAULT_SETTINGS, 'init2');
+    const fs3 = getFirestore(app);
+    const fs4 = getFirestore(app, 'name1');
+    const fs5 = getFirestore(app, 'name2');
+    expect(fs1).to.not.be.equal(fs2);
+    expect(fs1).to.not.be.equal(fs3);
+    expect(fs1).to.not.be.equal(fs4);
+    expect(fs1).to.not.be.equal(fs5);
     expect(fs2).to.not.be.equal(fs3);
+    expect(fs2).to.not.be.equal(fs4);
+    expect(fs2).to.not.be.equal(fs5);
+    expect(fs3).to.not.be.equal(fs4);
+    expect(fs3).to.not.be.equal(fs5);
+    expect(fs4).to.not.be.equal(fs5);
   });
 
   it('returns same default instance from default app', () => {
@@ -134,11 +144,15 @@ describe('Firestore', () => {
       apiKey: 'fake-api-key',
       projectId: 'test-project'
     });
-    const fs1 = getFirestore();
-    const fs2 = getFirestore(app);
-    const fs3 = getFirestore('(default)');
-    const fs4 = getFirestore(app, '(default)');
-    expect(fs1).to.be.equal(fs2).and.equal(fs3).and.equal(fs4);
+    const fs1 = initializeFirestore(app, DEFAULT_SETTINGS);
+    const fs2 = getFirestore();
+    const fs3 = getFirestore(app);
+    const fs4 = getFirestore('(default)');
+    const fs5 = getFirestore(app, '(default)');
+    expect(fs1).to.be.equal(fs2);
+    expect(fs1).to.be.equal(fs3);
+    expect(fs1).to.be.equal(fs4);
+    expect(fs1).to.be.equal(fs5);
   });
 
   it('returns different instance from different named app', () => {
@@ -154,7 +168,8 @@ describe('Firestore', () => {
     const fs1 = getFirestore();
     const fs2 = getFirestore(app1);
     const fs3 = getFirestore(app2);
-    expect(fs1).to.not.be.equal(fs2).and.equal(fs3);
+    expect(fs1).to.not.be.equal(fs2);
+    expect(fs1).to.not.be.equal(fs3);
     expect(fs2).to.not.be.equal(fs3);
   });
 

From 6291938a2fe436f3df7179e7ad544aec8b8374b5 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Wed, 10 Aug 2022 21:33:30 -0400
Subject: [PATCH 09/16] Expose API

---
 common/api-review/firestore-lite.api.md | 2 +-
 common/api-review/firestore.api.md      | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/common/api-review/firestore-lite.api.md b/common/api-review/firestore-lite.api.md
index c69f9d2da25..c220ad0810f 100644
--- a/common/api-review/firestore-lite.api.md
+++ b/common/api-review/firestore-lite.api.md
@@ -191,7 +191,7 @@ export function getFirestore(app: FirebaseApp, databaseId: string): Firestore;
 export function increment(n: number): FieldValue;
 
 // @public
-export function initializeFirestore(app: FirebaseApp, settings: Settings): Firestore;
+export function initializeFirestore(app: FirebaseApp, settings: Settings, databaseId?: string): Firestore;
 
 // @public
 export function limit(limit: number): QueryConstraint;
diff --git a/common/api-review/firestore.api.md b/common/api-review/firestore.api.md
index f34e846eb7d..4e6e29b883b 100644
--- a/common/api-review/firestore.api.md
+++ b/common/api-review/firestore.api.md
@@ -243,7 +243,7 @@ export function getFirestore(app: FirebaseApp, databaseId: string): Firestore;
 export function increment(n: number): FieldValue;
 
 // @public
-export function initializeFirestore(app: FirebaseApp, settings: FirestoreSettings): Firestore;
+export function initializeFirestore(app: FirebaseApp, settings: FirestoreSettings, databaseId?: string): Firestore;
 
 // @public
 export function limit(limit: number): QueryConstraint;

From a8b28d204410e8b43f80041eaff653248675d2ba Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Wed, 10 Aug 2022 22:03:27 -0400
Subject: [PATCH 10/16] Fix integration test

---
 integration/firestore/firebase_export.ts | 28 ++++++++++++++----------
 1 file changed, 17 insertions(+), 11 deletions(-)

diff --git a/integration/firestore/firebase_export.ts b/integration/firestore/firebase_export.ts
index 31371b34552..4646e11fe2c 100644
--- a/integration/firestore/firebase_export.ts
+++ b/integration/firestore/firebase_export.ts
@@ -27,19 +27,25 @@ import {
 
 let appCount = 0;
 
+export function newTestApp(projectId: string, appName?: string): FirebaseApp {
+  if (appName === undefined) {
+    appName = 'test-app-' + appCount++;
+  }
+  return initializeApp(
+    {
+      apiKey: 'fake-api-key',
+      projectId
+    },
+    appName
+  );
+}
+
 export function newTestFirestore(
-  projectId: string,
-  nameOrApp?: string | FirebaseApp,
-  settings?: FirestoreSettings
+  app: FirebaseApp,
+  settings?: FirestoreSettings,
+  dbName?: string
 ): Firestore {
-  if (nameOrApp === undefined) {
-    nameOrApp = 'test-app-' + appCount++;
-  }
-  const app =
-    typeof nameOrApp === 'string'
-      ? initializeApp({ apiKey: 'fake-api-key', projectId }, nameOrApp)
-      : nameOrApp;
-  return initializeFirestore(app, settings || {});
+  return initializeFirestore(app, settings || {}, dbName);
 }
 
 export * from '@firebase/firestore';

From 5f6159e55df9a0c4e0d8438a7bfcfd50c72c9bdf Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Wed, 10 Aug 2022 23:36:07 -0400
Subject: [PATCH 11/16] Fix import

---
 packages/firestore/test/integration/api/provider.test.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/firestore/test/integration/api/provider.test.ts b/packages/firestore/test/integration/api/provider.test.ts
index abcf2bc22b0..ffcd0e7f350 100644
--- a/packages/firestore/test/integration/api/provider.test.ts
+++ b/packages/firestore/test/integration/api/provider.test.ts
@@ -26,7 +26,7 @@ import {
   Firestore,
   terminate,
   getDoc
-} from '../../../src';
+} from '../util/firebase_export';
 import { DEFAULT_SETTINGS } from '../util/settings';
 
 use(chaiAsPromised);

From 2f955f8bd1b47632b1b22f895ae6bdcb2e76b49b Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Thu, 11 Aug 2022 09:33:20 -0400
Subject: [PATCH 12/16] Fix test

---
 packages/firestore/test/integration/api/database.test.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/firestore/test/integration/api/database.test.ts b/packages/firestore/test/integration/api/database.test.ts
index c39162ba858..244cd58bea0 100644
--- a/packages/firestore/test/integration/api/database.test.ts
+++ b/packages/firestore/test/integration/api/database.test.ts
@@ -1712,7 +1712,7 @@ apiDescribe('Database', (persistence: boolean) => {
   it('can keep docs separate with multi-db when online', () => {
     return withNamedTestDbs(
       persistence,
-      ['db1', 'db2', 'db1'],
+      ['db1', 'db2'],
       async ([db1, db2]) => {
         const data = { name: 'Rafi', email: 'abc@xyz.com' };
 
@@ -1732,7 +1732,7 @@ apiDescribe('Database', (persistence: boolean) => {
   it('can keep docs separate with multi-db when offline', () => {
     return withNamedTestDbs(
       persistence,
-      ['db1', 'db2', 'db1'],
+      ['db1', 'db2'],
       async ([db1, db2]) => {
         await disableNetwork(db1);
         await disableNetwork(db2);

From ff7ec249d98c66746000d2dd6105f3b5a653f011 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Thu, 11 Aug 2022 09:43:12 -0400
Subject: [PATCH 13/16] Whitespace

---
 .../test/integration/api/database.test.ts     | 62 ++++++++-----------
 1 file changed, 27 insertions(+), 35 deletions(-)

diff --git a/packages/firestore/test/integration/api/database.test.ts b/packages/firestore/test/integration/api/database.test.ts
index 244cd58bea0..5e2ac5cba11 100644
--- a/packages/firestore/test/integration/api/database.test.ts
+++ b/packages/firestore/test/integration/api/database.test.ts
@@ -1710,45 +1710,37 @@ apiDescribe('Database', (persistence: boolean) => {
   });
 
   it('can keep docs separate with multi-db when online', () => {
-    return withNamedTestDbs(
-      persistence,
-      ['db1', 'db2'],
-      async ([db1, db2]) => {
-        const data = { name: 'Rafi', email: 'abc@xyz.com' };
+    return withNamedTestDbs(persistence, ['db1', 'db2'], async ([db1, db2]) => {
+      const data = { name: 'Rafi', email: 'abc@xyz.com' };
 
-        const ref1 = await doc(collection(db1, 'users'));
-        await setDoc(ref1, data);
-        const snapshot1 = await getDoc(ref1);
-        expect(snapshot1.exists()).to.be.ok;
-        expect(snapshot1.data()).to.be.deep.equals(data);
+      const ref1 = await doc(collection(db1, 'users'));
+      await setDoc(ref1, data);
+      const snapshot1 = await getDoc(ref1);
+      expect(snapshot1.exists()).to.be.ok;
+      expect(snapshot1.data()).to.be.deep.equals(data);
 
-        const ref2 = await doc(collection(db2, 'users'));
-        const snapshot2 = await getDoc(ref2);
-        expect(snapshot2.exists()).to.not.be.ok;
-      }
-    );
+      const ref2 = await doc(collection(db2, 'users'));
+      const snapshot2 = await getDoc(ref2);
+      expect(snapshot2.exists()).to.not.be.ok;
+    });
   });
 
   it('can keep docs separate with multi-db when offline', () => {
-    return withNamedTestDbs(
-      persistence,
-      ['db1', 'db2'],
-      async ([db1, db2]) => {
-        await disableNetwork(db1);
-        await disableNetwork(db2);
-        const data = { name: 'Rafi', email: 'abc@xyz.com' };
-
-        const ref1 = await doc(collection(db1, 'users'));
-        void setDoc(ref1, data);
-        const snapshot = await getDocFromCache(ref1);
-        expect(snapshot.exists()).to.be.ok;
-        expect(snapshot.data()).to.be.deep.equals(data);
-
-        const ref2 = await doc(collection(db2, 'users'));
-        await expect(getDocFromCache(ref2)).to.eventually.rejectedWith(
-          'Failed to get document from cache.'
-        );
-      }
-    );
+    return withNamedTestDbs(persistence, ['db1', 'db2'], async ([db1, db2]) => {
+      await disableNetwork(db1);
+      await disableNetwork(db2);
+      const data = { name: 'Rafi', email: 'abc@xyz.com' };
+
+      const ref1 = await doc(collection(db1, 'users'));
+      void setDoc(ref1, data);
+      const snapshot = await getDocFromCache(ref1);
+      expect(snapshot.exists()).to.be.ok;
+      expect(snapshot.data()).to.be.deep.equals(data);
+
+      const ref2 = await doc(collection(db2, 'users'));
+      await expect(getDocFromCache(ref2)).to.eventually.rejectedWith(
+        'Failed to get document from cache.'
+      );
+    });
   });
 });

From 05e813f37ff51c0135af1a8da0f8068851ebd723 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Thu, 11 Aug 2022 12:03:29 -0400
Subject: [PATCH 14/16] Only use emulator for integration tests.

---
 packages/firestore/test/integration/api/database.test.ts | 6 +++---
 packages/firestore/test/integration/util/helpers.ts      | 9 ++++++++-
 2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/packages/firestore/test/integration/api/database.test.ts b/packages/firestore/test/integration/api/database.test.ts
index 5e2ac5cba11..18b290e936c 100644
--- a/packages/firestore/test/integration/api/database.test.ts
+++ b/packages/firestore/test/integration/api/database.test.ts
@@ -1713,14 +1713,14 @@ apiDescribe('Database', (persistence: boolean) => {
     return withNamedTestDbs(persistence, ['db1', 'db2'], async ([db1, db2]) => {
       const data = { name: 'Rafi', email: 'abc@xyz.com' };
 
-      const ref1 = await doc(collection(db1, 'users'));
+      const ref1 = await doc(collection(db1, 'users'), 'doc1');
       await setDoc(ref1, data);
       const snapshot1 = await getDoc(ref1);
       expect(snapshot1.exists()).to.be.ok;
       expect(snapshot1.data()).to.be.deep.equals(data);
 
-      const ref2 = await doc(collection(db2, 'users'));
-      const snapshot2 = await getDoc(ref2);
+      const ref2 = await doc(collection(db2, 'users'), 'doc1');
+      const snapshot2 = await getDocFromServer(ref2);
       expect(snapshot2.exists()).to.not.be.ok;
     });
   });
diff --git a/packages/firestore/test/integration/util/helpers.ts b/packages/firestore/test/integration/util/helpers.ts
index 9f778e00ebd..791c27efe80 100644
--- a/packages/firestore/test/integration/util/helpers.ts
+++ b/packages/firestore/test/integration/util/helpers.ts
@@ -37,7 +37,8 @@ import {
 import {
   ALT_PROJECT_ID,
   DEFAULT_PROJECT_ID,
-  DEFAULT_SETTINGS
+  DEFAULT_SETTINGS,
+  USE_EMULATOR
 } from './settings';
 
 /* eslint-disable no-restricted-globals */
@@ -207,6 +208,12 @@ export async function withNamedTestDbs(
   dbNames: string[],
   fn: (db: Firestore[]) => Promise<void>
 ): Promise<void> {
+  // Named DBs requires preparing project with DBs beforehand.
+  // Emulator does not DB to have been created beforehand.
+  // TODO: Improve integration testing to have more than just (default) available.
+  if (!USE_EMULATOR) {
+    return Promise.resolve();
+  }
   const app = newTestApp(DEFAULT_PROJECT_ID);
   const dbs: Firestore[] = [];
   for (const dbName of dbNames) {

From ab45518260e01c7c8e019ad294ddb5be891ba626 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Mon, 22 Aug 2022 11:07:18 -0400
Subject: [PATCH 15/16] Improve comments and function naming.

---
 packages/firestore/test/integration/api/database.test.ts | 6 +++---
 packages/firestore/test/integration/util/helpers.ts      | 9 +++++----
 2 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/packages/firestore/test/integration/api/database.test.ts b/packages/firestore/test/integration/api/database.test.ts
index 18b290e936c..75125f1fdef 100644
--- a/packages/firestore/test/integration/api/database.test.ts
+++ b/packages/firestore/test/integration/api/database.test.ts
@@ -73,7 +73,7 @@ import {
   withTestDbs,
   withTestDoc,
   withTestDocAndInitialData,
-  withNamedTestDbs
+  withNamedTestDbsOrSkipUnlessUsingEmulator
 } from '../util/helpers';
 import { DEFAULT_SETTINGS, DEFAULT_PROJECT_ID } from '../util/settings';
 
@@ -1710,7 +1710,7 @@ apiDescribe('Database', (persistence: boolean) => {
   });
 
   it('can keep docs separate with multi-db when online', () => {
-    return withNamedTestDbs(persistence, ['db1', 'db2'], async ([db1, db2]) => {
+    return withNamedTestDbsOrSkipUnlessUsingEmulator(persistence, ['db1', 'db2'], async ([db1, db2]) => {
       const data = { name: 'Rafi', email: 'abc@xyz.com' };
 
       const ref1 = await doc(collection(db1, 'users'), 'doc1');
@@ -1726,7 +1726,7 @@ apiDescribe('Database', (persistence: boolean) => {
   });
 
   it('can keep docs separate with multi-db when offline', () => {
-    return withNamedTestDbs(persistence, ['db1', 'db2'], async ([db1, db2]) => {
+    return withNamedTestDbsOrSkipUnlessUsingEmulator(persistence, ['db1', 'db2'], async ([db1, db2]) => {
       await disableNetwork(db1);
       await disableNetwork(db2);
       const data = { name: 'Rafi', email: 'abc@xyz.com' };
diff --git a/packages/firestore/test/integration/util/helpers.ts b/packages/firestore/test/integration/util/helpers.ts
index 791c27efe80..f2584916daf 100644
--- a/packages/firestore/test/integration/util/helpers.ts
+++ b/packages/firestore/test/integration/util/helpers.ts
@@ -203,14 +203,15 @@ export async function withTestDbsSettings(
   }
 }
 
-export async function withNamedTestDbs(
+export async function withNamedTestDbsOrSkipUnlessUsingEmulator(
   persistence: boolean,
   dbNames: string[],
   fn: (db: Firestore[]) => Promise<void>
 ): Promise<void> {
-  // Named DBs requires preparing project with DBs beforehand.
-  // Emulator does not DB to have been created beforehand.
-  // TODO: Improve integration testing to have more than just (default) available.
+  // Tests with named DBs can only run on emulator for now. This is because the
+  // emulator does not require DB to be created before use.
+  // TODO: Design ability to run named DB tests on backend. Maybe create DBs
+  // TODO: beforehand, or create DBs as part of test setup.
   if (!USE_EMULATOR) {
     return Promise.resolve();
   }

From 5c8a2fb4e0febb240852e74fbfac4aa5bca105b1 Mon Sep 17 00:00:00 2001
From: Tom Andersen <tomandersen@google.com>
Date: Mon, 22 Aug 2022 11:15:06 -0400
Subject: [PATCH 16/16] Make pretty

---
 .../test/integration/api/database.test.ts     | 62 +++++++++++--------
 1 file changed, 35 insertions(+), 27 deletions(-)

diff --git a/packages/firestore/test/integration/api/database.test.ts b/packages/firestore/test/integration/api/database.test.ts
index 75125f1fdef..5f3e2dc6c61 100644
--- a/packages/firestore/test/integration/api/database.test.ts
+++ b/packages/firestore/test/integration/api/database.test.ts
@@ -1710,37 +1710,45 @@ apiDescribe('Database', (persistence: boolean) => {
   });
 
   it('can keep docs separate with multi-db when online', () => {
-    return withNamedTestDbsOrSkipUnlessUsingEmulator(persistence, ['db1', 'db2'], async ([db1, db2]) => {
-      const data = { name: 'Rafi', email: 'abc@xyz.com' };
+    return withNamedTestDbsOrSkipUnlessUsingEmulator(
+      persistence,
+      ['db1', 'db2'],
+      async ([db1, db2]) => {
+        const data = { name: 'Rafi', email: 'abc@xyz.com' };
 
-      const ref1 = await doc(collection(db1, 'users'), 'doc1');
-      await setDoc(ref1, data);
-      const snapshot1 = await getDoc(ref1);
-      expect(snapshot1.exists()).to.be.ok;
-      expect(snapshot1.data()).to.be.deep.equals(data);
+        const ref1 = await doc(collection(db1, 'users'), 'doc1');
+        await setDoc(ref1, data);
+        const snapshot1 = await getDoc(ref1);
+        expect(snapshot1.exists()).to.be.ok;
+        expect(snapshot1.data()).to.be.deep.equals(data);
 
-      const ref2 = await doc(collection(db2, 'users'), 'doc1');
-      const snapshot2 = await getDocFromServer(ref2);
-      expect(snapshot2.exists()).to.not.be.ok;
-    });
+        const ref2 = await doc(collection(db2, 'users'), 'doc1');
+        const snapshot2 = await getDocFromServer(ref2);
+        expect(snapshot2.exists()).to.not.be.ok;
+      }
+    );
   });
 
   it('can keep docs separate with multi-db when offline', () => {
-    return withNamedTestDbsOrSkipUnlessUsingEmulator(persistence, ['db1', 'db2'], async ([db1, db2]) => {
-      await disableNetwork(db1);
-      await disableNetwork(db2);
-      const data = { name: 'Rafi', email: 'abc@xyz.com' };
-
-      const ref1 = await doc(collection(db1, 'users'));
-      void setDoc(ref1, data);
-      const snapshot = await getDocFromCache(ref1);
-      expect(snapshot.exists()).to.be.ok;
-      expect(snapshot.data()).to.be.deep.equals(data);
-
-      const ref2 = await doc(collection(db2, 'users'));
-      await expect(getDocFromCache(ref2)).to.eventually.rejectedWith(
-        'Failed to get document from cache.'
-      );
-    });
+    return withNamedTestDbsOrSkipUnlessUsingEmulator(
+      persistence,
+      ['db1', 'db2'],
+      async ([db1, db2]) => {
+        await disableNetwork(db1);
+        await disableNetwork(db2);
+        const data = { name: 'Rafi', email: 'abc@xyz.com' };
+
+        const ref1 = await doc(collection(db1, 'users'));
+        void setDoc(ref1, data);
+        const snapshot = await getDocFromCache(ref1);
+        expect(snapshot.exists()).to.be.ok;
+        expect(snapshot.data()).to.be.deep.equals(data);
+
+        const ref2 = await doc(collection(db2, 'users'));
+        await expect(getDocFromCache(ref2)).to.eventually.rejectedWith(
+          'Failed to get document from cache.'
+        );
+      }
+    );
   });
 });