Add error handling test cases for dispatcher

Introduce error-producing handlers to test command, query, and event dispatch processes. Ensure proper error propagation when handlers encounter failures. Validate that expected errors are correctly returned in all scenarios.

dispatcher_test.go

@@ -2,6 +2,7 @@ package stonecqrs
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"testing"
 )
@@ -49,6 +50,30 @@ func (handler *testEventHandler) Handle(
 	return nil
 }
 
+type testErrorHandler struct{}
+
+func (handler *testErrorHandler) Handle(
+	ctx context.Context, cmd Command,
+) ([]Event, error) {
+	return nil, errors.New("test error")
+}
+
+type testErrorQueryHandler struct{}
+
+func (handler *testErrorQueryHandler) Handle(
+	ctx context.Context, query Query,
+) (interface{}, error) {
+	return nil, errors.New("test error")
+}
+
+type testErrorEventHandler struct{}
+
+func (handler *testErrorEventHandler) Handle(
+	ctx context.Context, event Event,
+) error {
+	return errors.New("test error")
+}
+
 func Test_NewDispatcher(t *testing.T) {
 	d := NewDispatcher()
 	if d == nil {
@@ -98,7 +123,7 @@ func Test_UnknownEvent(t *testing.T) {
 		t.Fatal("expected error")
 	}
 
-	err = d.DispatchEvent(context.Background(), unknownEvent{})
+	_, err = d.DispatchQuery(context.Background(), unknownEvent{})
 
 	if err == nil {
 		t.Fatal("expected error")
@@ -110,3 +135,25 @@ func Test_UnknownEvent(t *testing.T) {
 		t.Fatal("expected error")
 	}
 }
+
+func Test_Error(t *testing.T) {
+	d := NewDispatcher()
+	d.RegisterCommandHandler(testCommand{}, &testErrorHandler{})
+	d.RegisterQueryHandler(testQuery{}, &testErrorQueryHandler{})
+	d.RegisterEventHandler(testEvent{}, &testErrorEventHandler{})
+
+	_, err := d.DispatchCommand(context.Background(), testCommand{})
+	if err == nil {
+		t.Fatal("expected error")
+	}
+
+	_, err = d.DispatchQuery(context.Background(), testQuery{})
+	if err == nil {
+		t.Fatal("expected error")
+	}
+
+	err = d.DispatchEvent(context.Background(), testEvent{})
+	if err == nil {
+		t.Fatal("expected error")
+	}
+}