Release v19.51.0

Added

• ChronicleFixture.UsesPerContextMongoDBHost in Cratis.Chronicle.XUnit.Integration: an in-process MongoDB fixture that opts in starts a fresh host for every test context and gives its databases a unique prefix, so writes a previous context's kernel flushes after shutdown cannot change the next context's results. It defaults to false; a fixture that overrides GetStorageConfigurator passes DatabaseNamePrefix to WithMongoDB. See the integration tests guide.

Fixed

• In-process MongoDB integration runs no longer intermittently overcount keyed events or let observers from an earlier test context consume the next context's events. (#4787)