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test(localdb): convergence polish — provable LWW race arbitration, collection serialization, dead-letter diagnostics

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Claude-Session: https://claude.ai/code/session_01BL2Vu1ESDQ9SCN4gVKkdts
This commit is contained in:
Joseph Doherty
2026-07-18 01:06:00 -04:00
parent c5352f3ed8
commit b2345c32d4
3 changed files with 69 additions and 8 deletions
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ZB.MOM.WW.LocalDb/tests/ZB.MOM.WW.LocalDb.Tests/Convergence/BidirectionalConvergenceTests.cs
+43 -8
View File
@@ -5,6 +5,7 @@ namespace ZB.MOM.WW.LocalDb.Tests.Convergence;
/// concurrent writes, an update/delete race, offline accumulation, restart-mid-stream, and a pruned-horizon
/// snapshot resync — each driven through the normal <c>ILocalDb</c> API while both sync sessions run.
/// </summary>
[Collection("Convergence")]
public sealed class BidirectionalConvergenceTests
{
[Fact]
@@ -38,26 +39,52 @@ public sealed class BidirectionalConvergenceTests
Assert.Equal(51, await ConvergenceFixture.CountOrdersAsync(fx.B));
}
// Update/delete race, serialized so the winner is PROVABLY HLC-arbitrated (same technique as
// ConcurrentWrites' shared key): each contender writes only after observing the other's
// replicated stamp, so its HLC is strictly higher and the expected LWW winner is deterministic —
// not just "both sides agree" (which would also pass if both agreed for a wrong reason).
[Fact]
public async Task UpdateDeleteRace_Converges()
public async Task UpdateDeleteRace_DeleteHasHigherHlc_DeleteWinsBothSides()
{
await using var fx = new ConvergenceFixture();
// Seed the contested key on both nodes and let it converge first.
await ConvergenceFixture.UpsertAsync(fx.A, 7, "SEED", 1);
await fx.StartAsync();
await fx.AssertConvergedAsync();
// Race: A updates the same pk while B deletes it, inside one window. Whichever HLC wins, both
// nodes must end identical (either the updated row on both, or absent on both).
// A updates; converge (B's clock has observed A's stamp); then B deletes -> provably higher HLC.
await ConvergenceFixture.UpsertAsync(fx.A, 7, "A_UPDATED", 99);
await fx.AssertConvergedAsync();
await ConvergenceFixture.DeleteAsync(fx.B, 7);
await fx.AssertConvergedAsync();
var a = await ConvergenceFixture.CountOrdersAsync(fx.A);
var b = await ConvergenceFixture.CountOrdersAsync(fx.B);
Assert.Equal(a, b); // identical outcome; AssertConverged already proved row-level identity
// The DELETE won on BOTH sides: row absent, row_version tombstoned.
Assert.Equal(0, await ConvergenceFixture.CountOrdersAsync(fx.A));
Assert.Equal(0, await ConvergenceFixture.CountOrdersAsync(fx.B));
Assert.True(await IsTombstoned(fx.A, 7), "A row_version for id=7 should be a tombstone");
Assert.True(await IsTombstoned(fx.B, 7), "B row_version for id=7 should be a tombstone");
}
[Fact]
public async Task UpdateDeleteRace_UpdateHasHigherHlc_UpdateWinsBothSides()
{
await using var fx = new ConvergenceFixture();
await ConvergenceFixture.UpsertAsync(fx.A, 7, "SEED", 1);
await fx.StartAsync();
await fx.AssertConvergedAsync();
// Mirrored: B deletes; converge (A's clock has observed the tombstone's stamp); then A
// re-writes the pk -> provably higher HLC -> the update resurrects the row on BOTH sides.
await ConvergenceFixture.DeleteAsync(fx.B, 7);
await fx.AssertConvergedAsync();
await ConvergenceFixture.UpsertAsync(fx.A, 7, "A_RESURRECTED", 99);
await fx.AssertConvergedAsync();
Assert.Equal((7L, "A_RESURRECTED", (long?)99), await ReadRow(fx.A, 7));
Assert.Equal((7L, "A_RESURRECTED", (long?)99), await ReadRow(fx.B, 7));
Assert.False(await IsTombstoned(fx.A, 7), "A row_version for id=7 should be live again");
Assert.False(await IsTombstoned(fx.B, 7), "B row_version for id=7 should be live again");
}
[Fact]
@@ -181,6 +208,14 @@ public sealed class BidirectionalConvergenceTests
Assert.Equal((7L, "SECOND", (long?)2), await ReadRow(fx.B, 7));
}
private static async Task<bool> IsTombstoned(ILocalDb db, long id)
{
var rows = await db.QueryAsync(
"SELECT is_tombstone FROM __localdb_row_version WHERE table_name = 'orders' AND pk_json = @pk",
static r => r.GetInt64(0), new { pk = $"{{\"id\":{id}}}" });
return Assert.Single(rows) != 0;
}
private static async Task<(long Id, string? Sku, long? Qty)> ReadRow(ILocalDb db, long id)
{
var rows = await db.QueryAsync(