CBG-5829: have better isgr test assertions

[gregns1]

CBG-5829

Helper function to assert on documnet details rather than just waiting for a specific version to arrive at a given peer.

Pre-review checklist

• Logging sensitive data? Make sure it's tagged (e.g. base.UD(docID), base.MD(dbName))
• Updated relevant information in the API specifications (such as endpoint descriptions, schemas, ...) in docs/api

Dependencies (if applicable)

• Link upstream PRs
• Update Go module dependencies when merged

Integration Tests

• https://jenkins.sgwdev.com/job/SyncGatewayIntegration-Pipeline/50/ (flake)

[factory-droid]

Droid finished @gregns1's task —— View job

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Review summary (validator pass): Most of the new ISGR test helpers look solid and should reduce flakiness. One edge case remains: the snapshot API currently can’t represent or validate legacy documents that truly have no HLV, which can make “peer unchanged” assertions misleading or fail unexpectedly.

[Copilot]

Copilot review overview

🟡 Changes recommended

The new HLV comparator lacks negative coverage for current and merge-version mismatches.

Review effort: Balanced
Findings: 1 · 1

Open (2)

• Add negative cases for SourceID, Version, and MergeVersions · New
• Correct reversed destination in replication comment · New

What changed in this PR

Adds stronger ISGR test assertions by comparing replicated document state across peers.

Changes:

• Adds reusable document replication assertion helpers.
• Validates HLVs, revision ancestry, channels, bodies, tombstones, and attachments.
• Migrates replication tests to the stronger assertions.

File	Description
rest/​utilities_testing_isgr.go	Implements ISGR document comparison helpers.
rest/​utilities_testing_isgr_test.go	Tests encoded-revision HLV comparisons.
rest/​revocation_test.go	Strengthens revocation replication checks.
rest/​replicatortest/​replicator_test.go	Migrates general replication assertions.
rest/​replicatortest/​replicator_test_legacy_rev_test.go	Migrates legacy-revision assertions.
rest/​replicatortest/​replicator_conflict_test.go	Strengthens conflict-resolution checks.
rest/​blip_api_crud_test.go	Strengthens process-revision replication validation.

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[torcolvin]

Drop the duplicate wait. WaitForDocReplicated already waits on source, tombstones included.

Suggested change

	source.WaitForTombstoneRevIDOnly(doc2ID, deleteVersion)
	sgrRunner.RequireDocReplicated(doc2ID, source, dest, deleteVersion)
	sgrRunner.WaitForDocReplicated(doc2ID, source, dest, deleteVersion)

[torcolvin]

Race in the v4 local-wins case: expVersion.CV is read from activeRT at lines 6554-6562, right after the replication starts and often before the conflict is resolved. Local wins mints a new CV, so the wait can time out on a stale CV. Pass only the rev tree ID and check the CV source after the wait. The remote-wins branch also gets a barrier through RequireDocUnchanged.

Lines 6550-6563 are outside the diff: once this is applied, you can delete that block and use *remoteWinsVersion in the remote-wins branch.

Suggested change

	sgrRunner.RequireDoc(docID, activeRT, rest.ExpectedISGRDoc{Version: expVersion})
	sgrRunner.RequireDoc(docID, passiveRT, passiveDocBeforeReplication)
	} else {
	sgrRunner.RequireDocReplicated(docID, activeRT, passiveRT, expVersion)
	sgrRunner.RequireDoc(docID, activeRT, rest.ExpectedISGRDoc{Version: expVersion})
	sgrRunner.RequireDocUnchanged(docID, activeRT, passiveRT, passiveDocBeforeReplication)
	} else {
	doc := sgrRunner.WaitForDocReplicated(docID, activeRT, passiveRT, test.expectedFinalVersion)
	if sgrRunner.IsV4Protocol() {
	// local wins mints a new CV on activeRT during resolution, so only its source is known up front
	assert.Equal(t, activeRT.GetDatabase().EncodedSourceID, doc.HLV.SourceID)
	}

[gregns1]

I'm made changes to make the code better on this test but we don't mint a new CV on local wins for HLV. only the rev tree ID changes.