Task mentions (#926)

Co-authored-by: kolaente <k@knt.li>
Reviewed-on: https://kolaente.dev/vikunja/api/pulls/926
Co-authored-by: konrad <konrad@kola-entertainments.de>
Co-committed-by: konrad <konrad@kola-entertainments.de>

pkg/events/testing.go

@@ -17,8 +17,12 @@
 package events
 
 import (
+	"encoding/json"
 	"testing"
 
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill/message"
+
 	"github.com/stretchr/testify/assert"
 )
 
@@ -47,3 +51,13 @@ func AssertDispatched(t *testing.T, event Event) {
 
 	assert.True(t, found, "Failed to assert "+event.Name()+" has been dispatched.")
 }
+
+// TestListener takes an event and a listener and calls the listener's Handle method.
+func TestListener(t *testing.T, event Event, listener Listener) {
+	content, err := json.Marshal(event)
+	assert.NoError(t, err)
+
+	msg := message.NewMessage(watermill.NewUUID(), content)
+	err = listener.Handle(msg)
+	assert.NoError(t, err)
+}