Introduced NowPlayingRepository. Don't do anything for now

engine/mock_nowplaying_repo.go

@@ -0,0 +1,28 @@
+package engine
+
+import (
+	"errors"
+	"time"
+)
+
+func CreateMockNowPlayingRepo() *MockNowPlaying {
+	return &MockNowPlaying{data: make(map[string]time.Time)}
+}
+
+type MockNowPlaying struct {
+	NowPlayingRepository
+	data map[string]time.Time
+	err  bool
+}
+
+func (m *MockNowPlaying) SetError(err bool) {
+	m.err = err
+}
+
+func (m *MockNowPlaying) Add(id string) error {
+	if m.err {
+		return errors.New("Error!")
+	}
+	m.data[id] = time.Now()
+	return nil
+}