OptionalconnectionEventStoreDB connection string, e.g.
'esdb://localhost:2113?tls=false'. Used to build the client via
EventStoreDBClient.connectionString(...).
OptionalclientA pre-built EventStoreDBClient (or a mock exposing the methods above).
When provided, connect() uses it directly and does NOT require the driver
— this is how tests inject a mock client.
Connection options for
EventStoreStore.