storage: emit AfterMessageDeleted events (#334)

* Ignore test lua script

Signed-off-by: James Hillyerd <james@hillyerd.com>

* Wire ExtHost into storage system
imports

Signed-off-by: James Hillyerd <james@hillyerd.com>

* storage/file: emit deleted events

Signed-off-by: James Hillyerd <james@hillyerd.com>

* storage/mem: emit deleted events

Signed-off-by: James Hillyerd <james@hillyerd.com>

---------

Signed-off-by: James Hillyerd <james@hillyerd.com>

pkg/extension/broker.go

@@ -1,6 +1,10 @@
 package extension
 
-import "sync"
+import (
+	"errors"
+	"sync"
+	"time"
+)
 
 // EventBroker maintains a list of listeners interested in a specific type
 // of event.
@@ -55,3 +59,38 @@ func (eb *EventBroker[E, R]) lockedRemoveListener(name string) {
 		}
 	}
 }
+
+// AsyncTestListener returns a func that will wait for an event and return it, or timeout
+// with an error.
+func (eb *EventBroker[E, R]) AsyncTestListener(capacity int) func() (*E, error) {
+	const name = "asyncTestListener"
+
+	// Send event down channel.
+	events := make(chan E, capacity)
+	eb.AddListener(name,
+		func(msg E) *R {
+			events <- msg
+			return nil
+		})
+
+	count := 0
+
+	return func() (*E, error) {
+		count++
+
+		defer func() {
+			if count >= capacity {
+				eb.RemoveListener(name)
+				close(events)
+			}
+		}()
+
+		select {
+		case event := <-events:
+			return &event, nil
+
+		case <-time.After(time.Second * 2):
+			return nil, errors.New("Timeout waiting for event")
+		}
+	}
+}

pkg/extension/host.go

@@ -20,8 +20,9 @@ type Host struct {
 // processed asynchronously with respect to the rest of Inbuckets operation.  However, an event
 // listener will not be called until the one before it complets.
 type Events struct {
-	AfterMessageStored EventBroker[event.MessageMetadata, Void]
-	BeforeMailAccepted EventBroker[event.AddressParts, bool]
+	AfterMessageDeleted EventBroker[event.MessageMetadata, Void]
+	AfterMessageStored  EventBroker[event.MessageMetadata, Void]
+	BeforeMailAccepted  EventBroker[event.AddressParts, bool]
 }
 
 // Void indicates the event emitter will ignore any value returned by listeners.