1 files changed, 79 insertions, 0 deletions
diff --git a/player-server/internal/thumb/path_test.go b/player-server/internal/thumb/path_test.go
new file mode 100644
index 0000000..c7f45f0
--- /dev/null
+++ b/player-server/internal/thumb/path_test.go
@@ -0,0 +1,79 @@
+package thumb
+
+import "testing"
+
+func TestThumbnailDir(t *testing.T) {
+	tests := []struct {
+		name   string
+		parent string
+		want   string
+	}{
+		{"simple", "/media/set1", "/media/set1/.thumbnails"},
+		{"trailing slash", "/media/set1/", "/media/set1/.thumbnails"},
+		{"double trailing slash", "/media/set1//", "/media/set1/.thumbnails"},
+		{"relative", "set1", "set1/.thumbnails"},
+		{"empty parent", "", ".thumbnails"},
+		{"root", "/", "/.thumbnails"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := ThumbnailDir(tt.parent); got != tt.want {
+				t.Errorf("ThumbnailDir(%q) = %q, want %q", tt.parent, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestThumbnailNameFor(t *testing.T) {
+	tests := []struct {
+		name    string
+		srcPath string
+		want    string
+	}{
+		{"video mp4", "/media/set1/clip.mp4", "clip.jpg"},
+		{"image jpg", "/media/set1/photo.JPG", "photo.jpg"},
+		{"audio with cover", "/media/set1/song.mp3", "song.jpg"},
+		{"no extension", "/media/set1/README", "README.jpg"},
+		{"multi-dot filename", "/media/set1/my.movie.final.mkv", "my.movie.final.jpg"},
+		{"dotfile", "/media/set1/.bashrc", ".jpg"},
+		{"just basename", "clip.mp4", "clip.jpg"},
+		{"path with trailing slash", "/media/set1/clip.mp4/", "clip.jpg"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := ThumbnailNameFor(tt.srcPath); got != tt.want {
+				t.Errorf("ThumbnailNameFor(%q) = %q, want %q", tt.srcPath, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestThumbnailPathFor(t *testing.T) {
+	tests := []struct {
+		name    string
+		srcPath string
+		parent  string
+		want    string
+	}{
+		{"video", "/media/set1/clip.mp4", "/media/set1", "/media/set1/.thumbnails/clip.jpg"},
+		{"image trailing slash parent", "/media/set1/photo.jpg", "/media/set1/", "/media/set1/.thumbnails/photo.jpg"},
+		{"src elsewhere", "/uploads/raw/photo.png", "/media/set1", "/media/set1/.thumbnails/photo.jpg"},
+		{"relative", "clip.mp4", "set1", "set1/.thumbnails/clip.jpg"},
+		{"no extension", "/media/set1/RAW", "/media/set1", "/media/set1/.thumbnails/RAW.jpg"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := ThumbnailPathFor(tt.srcPath, tt.parent); got != tt.want {
+				t.Errorf("ThumbnailPathFor(%q, %q) = %q, want %q", tt.srcPath, tt.parent, got, tt.want)
+			}
+		})
+	}
+}
+
+// TestDirNameConstant guards the on-disk convention; many tests in
+// internal/service compare against the literal ".thumbnails" name.
+func TestDirNameConstant(t *testing.T) {
+	if DirName != ".thumbnails" {
+		t.Errorf("DirName = %q, want %q (changing this breaks on-disk layout)", DirName, ".thumbnails")
+	}
+}