Fix Firestore failing to return empty results from the local cache

.changeset/cool-grapes-attend.md

@@ -1,5 +1,6 @@
 ---
 '@firebase/firestore': patch
+'firebase': patch
 ---
 
 Fix Firestore failing to raise initial snapshot from empty local cache result

packages/firestore/src/core/event_manager.ts

@@ -308,7 +308,7 @@ export class QueryListener {
         snap.fromCache,
         snap.syncStateChanged,
         /* excludesMetadataChanges= */ true,
-        snap.resumeToken
+        snap.hasCachedResults
       );
     }
     let raisedEvent = false;
@@ -372,11 +372,11 @@ export class QueryListener {
       return false;
     }
 
-    // Raise data from cache if we have any documents or resume token,
+    // Raise data from cache if we have any documents, have cached results before,
     // or we are offline.
     return (
       !snap.docs.isEmpty() ||
-      snap.resumeToken.approximateByteSize() > 0 ||
+      snap.hasCachedResults ||
       onlineState === OnlineState.Offline
     );
   }
@@ -412,7 +412,7 @@ export class QueryListener {
       snap.docs,
       snap.mutatedKeys,
       snap.fromCache,
-      snap.resumeToken
+      snap.hasCachedResults
     );
     this.raisedInitialEvent = true;
     this.queryObserver.next(snap);

packages/firestore/src/core/view.ts

@@ -26,7 +26,6 @@ import { DocumentKey } from '../model/document_key';
 import { DocumentSet } from '../model/document_set';
 import { TargetChange } from '../remote/remote_event';
 import { debugAssert, fail } from '../util/assert';
-import { ByteString } from '../util/byte_string';
 
 import { LimitType, newQueryComparator, Query, queryMatches } from './query';
 import { OnlineState } from './types';
@@ -73,7 +72,7 @@ export interface ViewChange {
  */
 export class View {
   private syncState: SyncState | null = null;
-  private resumeToken: ByteString | null = null;
+  private hasCachedResults: boolean = false;
   /**
    * A flag whether the view is current with the backend. A view is considered
    * current after it has seen the current flag from the backend and did not
@@ -322,7 +321,8 @@ export class View {
         newSyncState === SyncState.Local,
         syncStateChanged,
         /* excludesMetadataChanges= */ false,
-        targetChange?.resumeToken ?? ByteString.EMPTY_BYTE_STRING
+        targetChange !== undefined &&
+          targetChange.resumeToken.approximateByteSize() > 0
       );
       return {
         snapshot: snap,
@@ -472,7 +472,7 @@ export class View {
       this.documentSet,
       this.mutatedKeys,
       this.syncState === SyncState.Local,
-      this.resumeToken ?? ByteString.EMPTY_BYTE_STRING
+      this.hasCachedResults
     );
   }
 }

packages/firestore/src/core/view_snapshot.ts

@@ -20,7 +20,6 @@ import { Document } from '../model/document';
 import { DocumentKey } from '../model/document_key';
 import { DocumentSet } from '../model/document_set';
 import { fail } from '../util/assert';
-import { ByteString } from '../util/byte_string';
 import { SortedMap } from '../util/sorted_map';
 
 import { Query, queryEquals } from './query';
@@ -148,7 +147,7 @@ export class ViewSnapshot {
     readonly fromCache: boolean,
     readonly syncStateChanged: boolean,
     readonly excludesMetadataChanges: boolean,
-    readonly resumeToken: ByteString
+    readonly hasCachedResults: boolean
   ) {}
 
   /** Returns a view snapshot as if all documents in the snapshot were added. */
@@ -157,7 +156,7 @@ export class ViewSnapshot {
     documents: DocumentSet,
     mutatedKeys: DocumentKeySet,
     fromCache: boolean,
-    resumeToken: ByteString
+    hasCachedResults: boolean
   ): ViewSnapshot {
     const changes: DocumentViewChange[] = [];
     documents.forEach(doc => {
@@ -173,7 +172,7 @@ export class ViewSnapshot {
       fromCache,
       /* syncStateChanged= */ true,
       /* excludesMetadataChanges= */ false,
-      resumeToken
+      hasCachedResults
     );
   }
 
@@ -184,6 +183,7 @@ export class ViewSnapshot {
   isEqual(other: ViewSnapshot): boolean {
     if (
       this.fromCache !== other.fromCache ||
+      this.hasCachedResults !== other.hasCachedResults ||
       this.syncStateChanged !== other.syncStateChanged ||
       !this.mutatedKeys.isEqual(other.mutatedKeys) ||
       !queryEquals(this.query, other.query) ||

packages/firestore/test/unit/api/database.test.ts

@@ -25,8 +25,6 @@ import {
 } from '../../../src';
 import { EmulatorAuthCredentialsProvider } from '../../../src/api/credentials';
 import { User } from '../../../src/auth/user';
-import { encodeBase64 } from '../../../src/platform/base64';
-import { ByteString } from '../../../src/util/byte_string';
 import {
   collectionReference,
   documentReference,
@@ -179,48 +177,51 @@ describe('QuerySnapshot', () => {
         querySnapshot('foo', {}, { a: { a: 1 } }, keys('foo/a'), false, true)
       )
     ).to.be.false;
-  });
-
-  it('resume token should not effect querySnapshot equality', () => {
-    const resumeToken1 = ByteString.fromBase64String(
-      encodeBase64('ResumeToken1')
-    );
-    const resumeToken1Copy = ByteString.fromBase64String(
-      encodeBase64('ResumeToken1')
-    );
-    const resumeToken2 = ByteString.fromBase64String(
-      encodeBase64('ResumeToken2')
-    );
-
-    const snapshot1 = querySnapshot(
-      'foo',
-      {},
-      { a: { a: 1 } },
-      keys(),
-      false,
-      false,
-      resumeToken1
-    );
-    const snapshot1Copy = querySnapshot(
-      'foo',
-      {},
-      { a: { a: 1 } },
-      keys(),
-      false,
-      false,
-      resumeToken1Copy
-    );
-    const snapshot2 = querySnapshot(
-      'foo',
-      {},
-      { a: { a: 1 } },
-      keys(),
-      false,
-      false,
-      resumeToken2
-    );
-    expect(snapshotEqual(snapshot1, snapshot1Copy)).to.be.true;
-    expect(snapshotEqual(snapshot1, snapshot2)).to.be.true;
+    // hasCachedResults should effect querySnapshot equality
+    expect(
+      snapshotEqual(
+        querySnapshot(
+          'foo',
+          {},
+          { a: { a: 1 } },
+          keys('foo/a'),
+          false,
+          false,
+          true
+        ),
+        querySnapshot(
+          'foo',
+          {},
+          { a: { a: 1 } },
+          keys('foo/a'),
+          false,
+          false,
+          true
+        )
+      )
+    ).to.be.true;
+    expect(
+      snapshotEqual(
+        querySnapshot(
+          'foo',
+          {},
+          { a: { a: 1 } },
+          keys('foo/a'),
+          false,
+          false,
+          true
+        ),
+        querySnapshot(
+          'foo',
+          {},
+          { a: { a: 1 } },
+          keys('foo/a'),
+          false,
+          false,
+          false
+        )
+      )
+    ).to.be.false;
   });
 
   it('JSON.stringify() does not throw', () => {

packages/firestore/test/unit/core/event_manager.test.ts

@@ -225,7 +225,7 @@ describe('QueryListener', () => {
       fromCache: snap2.fromCache,
       syncStateChanged: true,
       mutatedKeys: keys(),
-      resumeToken: snap2.resumeToken
+      hasCachedResults: snap2.hasCachedResults
     };
     expect(otherEvents).to.deep.equal([expectedSnap2]);
   });
@@ -398,7 +398,7 @@ describe('QueryListener', () => {
         fromCache: snap2.fromCache,
         syncStateChanged: snap2.syncStateChanged,
         mutatedKeys: snap2.mutatedKeys,
-        resumeToken: snap2.resumeToken
+        hasCachedResults: snap2.hasCachedResults
       };
       expect(filteredEvents).to.deep.equal([snap1, expectedSnap2]);
     }
@@ -485,7 +485,7 @@ describe('QueryListener', () => {
       fromCache: false,
       syncStateChanged: true,
       mutatedKeys: keys(),
-      resumeToken: snap3.resumeToken
+      hasCachedResults: snap3.hasCachedResults
     };
     expect(events).to.deep.equal([expectedSnap]);
   });
@@ -521,7 +521,7 @@ describe('QueryListener', () => {
       fromCache: true,
       syncStateChanged: true,
       mutatedKeys: keys(),
-      resumeToken: snap1.resumeToken
+      hasCachedResults: snap1.hasCachedResults
     };
     const expectedSnap2 = {
       query: query1,
@@ -531,7 +531,7 @@ describe('QueryListener', () => {
       fromCache: true,
       syncStateChanged: false,
       mutatedKeys: keys(),
-      resumeToken: snap2.resumeToken
+      hasCachedResults: snap2.hasCachedResults
     };
     expect(events).to.deep.equal([expectedSnap1, expectedSnap2]);
   });
@@ -558,7 +558,7 @@ describe('QueryListener', () => {
       fromCache: true,
       syncStateChanged: true,
       mutatedKeys: keys(),
-      resumeToken: snap1.resumeToken
+      hasCachedResults: snap1.hasCachedResults
     };
     expect(events).to.deep.equal([expectedSnap]);
   });
@@ -584,7 +584,7 @@ describe('QueryListener', () => {
       fromCache: true,
       syncStateChanged: true,
       mutatedKeys: keys(),
-      resumeToken: snap1.resumeToken
+      hasCachedResults: snap1.hasCachedResults
     };
     expect(events).to.deep.equal([expectedSnap]);
   });

packages/firestore/test/unit/specs/listen_spec.test.ts

@@ -1764,7 +1764,7 @@ describeSpec('Listens:', [], () => {
           .client(1)
           // Re-listen to the query in second client and verify that the empty
           // snapshot is raised from cache.
-          .userListens(query1, { resumeToken: 'resume-token-1000' })
+          .userListens(query1)
           .expectEvents(query1, { fromCache: true })
           .client(0)
           .expectListen(query1, { resumeToken: 'resume-token-1000' })

packages/firestore/test/util/api_helpers.ts

@@ -43,7 +43,6 @@ import {
 import { DocumentKeySet } from '../../src/model/collections';
 import { DocumentSet } from '../../src/model/document_set';
 import { JsonObject } from '../../src/model/object_value';
-import { ByteString } from '../../src/util/byte_string';
 import { TEST_PROJECT } from '../unit/local/persistence_test_helpers';
 
 import { doc, key, path as pathFrom } from './helpers';
@@ -132,7 +131,7 @@ export function querySnapshot(
   mutatedKeys: DocumentKeySet,
   fromCache: boolean,
   syncStateChanged: boolean,
-  resumeToken?: ByteString
+  hasCachedResults?: boolean
 ): QuerySnapshot {
   const query: InternalQuery = newQueryForPath(pathFrom(path));
   let oldDocuments: DocumentSet = new DocumentSet();
@@ -155,7 +154,7 @@ export function querySnapshot(
     fromCache,
     syncStateChanged,
     false,
-    resumeToken ?? ByteString.EMPTY_BYTE_STRING
+    hasCachedResults ?? false
   );
   const db = firestore();
   return new QuerySnapshot(