test(subsonic): cover stream helpers (#296)

findSidecarCover priority (cover.* wins over folder.*), imageContentType
mapping, and nowPlayingMap write/read round-trip.

internal/subsonic/stream_test.go

@@ -0,0 +1,78 @@
+package subsonic
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/jackc/pgx/v5/pgtype"
+)
+
+func TestFindSidecarCover(t *testing.T) {
+	dir := t.TempDir()
+	track := filepath.Join(dir, "01 - song.mp3")
+	if err := os.WriteFile(track, []byte("audio"), 0o644); err != nil {
+		t.Fatalf("write track: %v", err)
+	}
+
+	// Empty dir first: no cover.
+	if got := findSidecarCover(track); got != "" {
+		t.Errorf("no sidecar → %q, want empty", got)
+	}
+
+	// folder.jpg lower priority than cover.jpg: add folder first, expect hit;
+	// then add cover.jpg, expect cover to win.
+	folder := filepath.Join(dir, "folder.jpg")
+	if err := os.WriteFile(folder, []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if got := findSidecarCover(track); got != folder {
+		t.Errorf("folder.jpg fallback = %q, want %q", got, folder)
+	}
+	cover := filepath.Join(dir, "cover.jpg")
+	if err := os.WriteFile(cover, []byte("jpg"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if got := findSidecarCover(track); got != cover {
+		t.Errorf("cover.jpg priority = %q, want %q", got, cover)
+	}
+}
+
+func TestImageContentType(t *testing.T) {
+	cases := map[string]string{
+		"cover.jpg":    "image/jpeg",
+		"cover.JPEG":   "image/jpeg",
+		"art.png":      "image/png",
+		"thumb.gif":    "image/gif",
+		"square.webp":  "image/webp",
+		"unknown.tiff": "application/octet-stream",
+	}
+	for in, want := range cases {
+		if got := imageContentType(in); got != want {
+			t.Errorf("imageContentType(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+func TestNowPlayingMap(t *testing.T) {
+	m := newNowPlayingMap()
+	user := "user-1"
+	if _, ok := m.Get(user); ok {
+		t.Fatalf("unexpected entry on fresh map")
+	}
+
+	var trackID pgtype.UUID
+	_ = trackID.Scan("6ba7b810-9dad-11d1-80b4-00c04fd430c8")
+	m.Set(user, trackID)
+
+	entry, ok := m.Get(user)
+	if !ok {
+		t.Fatalf("Set did not persist")
+	}
+	if uuidToID(entry.TrackID) != "6ba7b810-9dad-11d1-80b4-00c04fd430c8" {
+		t.Errorf("trackID round-trip broke: %q", uuidToID(entry.TrackID))
+	}
+	if entry.At.IsZero() {
+		t.Errorf("At timestamp not set")
+	}
+}