Fallback extracting tags using ffmpeg

tests/mock_ffmpeg.go

@@ -0,0 +1,52 @@
+package tests
+
+import (
+	"context"
+	"io"
+	"strings"
+	"sync"
+
+	"github.com/navidrome/navidrome/consts"
+	"github.com/navidrome/navidrome/resources"
+	"github.com/navidrome/navidrome/utils"
+)
+
+func NewMockFFmpeg(data string) *MockFFmpeg {
+	return &MockFFmpeg{Reader: strings.NewReader(data)}
+}
+
+type MockFFmpeg struct {
+	io.Reader
+	lock   sync.Mutex
+	closed utils.AtomicBool
+	Error  error
+}
+
+func (ff *MockFFmpeg) Transcode(ctx context.Context, cmd, path string, maxBitRate int) (f io.ReadCloser, err error) {
+	if ff.Error != nil {
+		return nil, ff.Error
+	}
+	return ff, nil
+}
+
+func (ff *MockFFmpeg) ExtractImage(ctx context.Context, path string) (io.ReadCloser, error) {
+	if ff.Error != nil {
+		return nil, ff.Error
+	}
+	return resources.FS().Open(consts.PlaceholderAlbumArt)
+}
+
+func (ff *MockFFmpeg) Read(p []byte) (n int, err error) {
+	ff.lock.Lock()
+	defer ff.lock.Unlock()
+	return ff.Reader.Read(p)
+}
+
+func (ff *MockFFmpeg) Close() error {
+	ff.closed.Set(true)
+	return nil
+}
+
+func (ff *MockFFmpeg) IsClosed() bool {
+	return ff.closed.Get()
+}