chore: enhance reset batch event handler test to verify account clearance after reset

Signed-off-by: Yordis Prieto <yordis.prieto@gmail.com>

Author: yordis

test/event/reset_batch_event_handler_test.exs

@@ -41,10 +41,11 @@ defmodule Commanded.Event.BatchResetEventHandlerTest do
     test "should be reset when starting from `:current`" do
       stream_uuid = UUID.uuid4()
 
-      # Ignored initial events
+      # Ignored initial events - add these BEFORE starting the handler
       initial_events = [%BankAccountOpened{account_number: "ACC123", initial_balance: 1_000}]
       :ok = EventStore.append_to_stream(BankApp, stream_uuid, 0, to_event_data(initial_events))
 
+      # Start handler with :current - should ignore existing events
       handler = start_supervised!({BankAccountBatchHandler, start_from: :current})
 
       Wait.until(fn ->
@@ -53,8 +54,27 @@ defmodule Commanded.Event.BatchResetEventHandlerTest do
 
       :ok = BankAccountBatchHandler.change_prefix("PREF_")
 
+      # Use a more robust reset approach with proper synchronization
+      ref = Process.monitor(handler)
       send(handler, :reset)
 
+      # Wait for the reset message to be processed
+      receive do
+        {:DOWN, ^ref, :process, ^handler, _reason} ->
+          # Handler died, this shouldn't happen
+          flunk("Handler died during reset")
+      after
+        100 -> :ok  # Reset message should be processed by now
+      end
+
+      Process.demonitor(ref)
+
+      # Ensure reset completed and accounts are cleared
+      Wait.until(fn ->
+        assert BankAccountBatchHandler.current_accounts() == []
+      end)
+
+      # Add new event after reset
       new_event = [%BankAccountOpened{account_number: "ACC1234", initial_balance: 1_000}]
       :ok = EventStore.append_to_stream(BankApp, stream_uuid, 1, to_event_data(new_event))