Fix Firestore failing to return empty results from the local cache

[dconeybe]

Fix a bug where Firestore fails to return results from the local cache if the result set was empty.

This bug is due to the following logic in event_manager.ts:

firebase-js-sdk/packages/firestore/src/core/event_manager.ts

Lines 374 to 375 in 4ddf556

	// Raise data from cache if we have any documents or we are offline
	return !snap.docs.isEmpty() || onlineState === OnlineState.Offline;

where it

which assumes that if the result set from the local cache is empty that there is no cached result; however, if the result set of the query is indeed empty then it should be returning that empty result set from the cache.

This fix improves the logic to use the presence of a resume token for the query to indicate that the empty result set is cached data and should be raised to the client.

Fixed #5873

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Latest commit: dfb45ad

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[google-oss-bot]

Size Analysis Report ¹

Affected Products

• @firebase/firestore

  • enableMultiTabIndexedDbPersistence

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	206 kB	207 kB	+349 B (+0.2%)
    size-with-ext-deps	266 kB	267 kB	+349 B (+0.1%)

  • getDoc

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	132 kB	133 kB	+362 B (+0.3%)
    size-with-ext-deps	192 kB	192 kB	+362 B (+0.2%)

  • getDocFromServer

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	132 kB	133 kB	+362 B (+0.3%)
    size-with-ext-deps	192 kB	192 kB	+362 B (+0.2%)

  • getDocs

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	134 kB	134 kB	+362 B (+0.3%)
    size-with-ext-deps	193 kB	194 kB	+362 B (+0.2%)

  • getDocsFromCache

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	96.3 kB	96.6 kB	+309 B (+0.3%)
    size-with-ext-deps	155 kB	156 kB	+309 B (+0.2%)

  • getDocsFromServer

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	134 kB	134 kB	+362 B (+0.3%)
    size-with-ext-deps	193 kB	194 kB	+362 B (+0.2%)

  • onSnapshot

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	134 kB	135 kB	+362 B (+0.3%)
    size-with-ext-deps	194 kB	194 kB	+362 B (+0.2%)

  • onSnapshotsInSync

    Size

    Type	Base (e35db6f)	Merge (3ef2847)	Diff
    size	124 kB	124 kB	+314 B (+0.3%)
    size-with-ext-deps	183 kB	184 kB	+314 B (+0.2%)

Test Logs

• Base (e35db6f): https://github.com/firebase/firebase-js-sdk/actions/runs/3070363706
• Merge (3ef2847): https://github.com/firebase/firebase-js-sdk/actions/runs/3085279855

1. https://storage.googleapis.com/firebase-sdk-metric-reports/wqHd6oBDMp.html

[dconeybe]

Closing since this PR was obsoleted by #6624