Snapshot dropping.

debian/snapshot.go

@@ -224,3 +224,29 @@ func (collection *SnapshotCollection) ForEach(handler func(*Snapshot) error) err
 func (collection *SnapshotCollection) Len() int {
 	return len(collection.list)
 }
+
+// Drop removes snapshot from collection
+func (collection *SnapshotCollection) Drop(snapshot *Snapshot) error {
+	snapshotPosition := -1
+
+	for i, s := range collection.list {
+		if s == snapshot {
+			snapshotPosition = i
+			break
+		}
+	}
+
+	if snapshotPosition == -1 {
+		panic("snapshot not found!")
+	}
+
+	collection.list[len(collection.list)-1], collection.list[snapshotPosition], collection.list =
+		nil, collection.list[len(collection.list)-1], collection.list[:len(collection.list)-1]
+
+	err := collection.db.Delete(snapshot.Key())
+	if err != nil {
+		return err
+	}
+
+	return collection.db.Delete(snapshot.RefKey())
+}

debian/snapshot_test.go

@@ -170,3 +170,24 @@ func (s *SnapshotCollectionSuite) TestFindByRemoteRepoSource(c *C) {
 
 	c.Check(s.collection.ByRemoteRepoSource(repo3), DeepEquals, []*Snapshot{})
 }
+
+func (s *SnapshotCollectionSuite) TestDrop(c *C) {
+	s.collection.Add(s.snapshot1)
+	s.collection.Add(s.snapshot2)
+
+	snap, _ := s.collection.ByUUID(s.snapshot1.UUID)
+	c.Check(snap, Equals, s.snapshot1)
+
+	err := s.collection.Drop(s.snapshot1)
+	c.Check(err, IsNil)
+
+	_, err = s.collection.ByUUID(s.snapshot1.UUID)
+	c.Check(err, ErrorMatches, "snapshot .* not found")
+
+	collection := NewSnapshotCollection(s.db)
+
+	_, err = collection.ByUUID(s.snapshot1.UUID)
+	c.Check(err, ErrorMatches, "snapshot .* not found")
+
+	c.Check(func() { s.collection.Drop(s.snapshot1) }, Panics, "snapshot not found!")
+}