test: impl StoreStub.MarkSeen (#443)

* test: impl StoreStub.MarkSeen

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

* continue to Message interface in StoreStub

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

* test errors

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

---------

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

pkg/test/storage.go

@@ -9,8 +9,8 @@ import (
 // StoreStub stubs storage.Store for testing.
 type StoreStub struct {
 	storage.Store
-	mailboxes map[string][]storage.Message
-	deleted   map[storage.Message]struct{}
+	mailboxes map[string][]storage.Message // Stored messages, by mailbox.
+	deleted   map[storage.Message]struct{} // Deleted message references.
 }
 
 // NewStore creates a new StoreStub.
@@ -25,7 +25,7 @@ func NewStore() *StoreStub {
 func (s *StoreStub) AddMessage(m storage.Message) (id string, err error) {
 	mb := m.Mailbox()
 	msgs := s.mailboxes[mb]
-	s.mailboxes[mb] = append(msgs, m)
+	s.mailboxes[mb] = append(msgs, &MessageStub{Message: m})
 	return m.ID(), nil
 }
 
@@ -50,34 +50,57 @@ func (s *StoreStub) GetMessages(mailbox string) ([]storage.Message, error) {
 	return s.mailboxes[mailbox], nil
 }
 
+// MarkSeen marks the message as having been seen.
+func (s *StoreStub) MarkSeen(mailbox, id string) error {
+	if mailbox == "messageerr" {
+		return errors.New("internal error")
+	}
+	for _, m := range s.mailboxes[mailbox] {
+		if m.ID() == id {
+			if stub, ok := m.(*MessageStub); ok {
+				stub.seen = true
+				return nil
+			}
+			return errors.New("unexpected type in StoreStub.mailboxes")
+		}
+	}
+	return storage.ErrNotExist
+}
+
 // RemoveMessage deletes a message by ID from the specified mailbox.
 func (s *StoreStub) RemoveMessage(mailbox, id string) error {
-	mb, ok := s.mailboxes[mailbox]
-	if ok {
-		var msg storage.Message
+	if mb, ok := s.mailboxes[mailbox]; ok {
+		var removed storage.Message
 		for i, m := range mb {
 			if m.ID() == id {
-				msg = m
+				removed = m
 				s.mailboxes[mailbox] = append(mb[:i], mb[i+1:]...)
 				break
 			}
 		}
-		if msg != nil {
-			s.deleted[msg] = struct{}{}
-			return nil
+
+		if removed != nil {
+			// Clients will be checking for their original storage.Message, not our wrapper.
+			if stub, ok := removed.(*MessageStub); ok {
+				s.deleted[stub.Message] = struct{}{}
+				return nil
+			}
+			return errors.New("unexpected type in StoreStub.mailboxes")
 		}
 	}
+
 	return storage.ErrNotExist
 }
 
 // VisitMailboxes accepts a function that will be called with the messages in each mailbox while it
 // continues to return true.
 func (s *StoreStub) VisitMailboxes(f func([]storage.Message) (cont bool)) error {
-	for _, v := range s.mailboxes {
-		if !f(v) {
+	for _, msgs := range s.mailboxes {
+		if !f(msgs) {
 			return nil
 		}
 	}
+
 	return nil
 }
 
@@ -86,3 +109,14 @@ func (s *StoreStub) MessageDeleted(m storage.Message) bool {
 	_, ok := s.deleted[m]
 	return ok
 }
+
+// MessageStub wraps a storage.Message with "seen" functionality.
+type MessageStub struct {
+	storage.Message
+	seen bool
+}
+
+// Seen returns true if the message has been marked as seen previously.
+func (m *MessageStub) Seen() bool {
+	return m.seen
+}