diff --git a/internal/photoprism/label_test.go b/internal/photoprism/label_test.go
index b6d7d774f..6ddd6b3de 100644
--- a/internal/photoprism/label_test.go
+++ b/internal/photoprism/label_test.go
@@ -79,4 +79,84 @@ func TestLabels_Title(t *testing.T) {
 
 		assert.Equal(t, "fallback", labels.Title("fallback"))
 	})
+
+	t.Run("empty fallback", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 80, Priority: 5}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 80, Priority: 4}
+		labels := Labels{cat, dog}
+
+		assert.Equal(t, "", labels.Title(""))
+	})
+
+	t.Run("empty labels", func(t *testing.T) {
+		labels := Labels{}
+
+		assert.Equal(t, "fallback", labels.Title("fallback"))
+	})
+
+	t.Run("priority < 0", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 61, Priority: -5}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 10, Priority: -4}
+		labels := Labels{cat, dog}
+
+		assert.Equal(t, "fallback", labels.Title("fallback"))
+	})
+
+	t.Run("priority == 0", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 60, Priority: 0}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 51, Priority: 0}
+		labels := Labels{cat, dog}
+
+		assert.Equal(t, "fallback", labels.Title("fallback"))
+	})
+}
+
+func TestLabels_Len(t *testing.T) {
+	t.Run("len = 2", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 59, Priority: 5}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 10, Priority: 4}
+		labels := Labels{cat, dog}
+		assert.Equal(t, 2, labels.Len())
+	})
+}
+
+func TestLabels_Swap(t *testing.T) {
+	t.Run("swap cat with dog", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 59, Priority: 5}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 10, Priority: 4}
+		labels := Labels{cat, dog}
+		assert.Equal(t, "dog", labels[1].Name)
+		labels.Swap(0, 1)
+		assert.Equal(t, "cat", labels[1].Name)
+	})
+}
+
+func TestLabels_Less(t *testing.T) {
+	t.Run("different priorities", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 59, Priority: 5}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 10, Priority: 4}
+		labels := Labels{cat, dog}
+		assert.Equal(t, "dog", labels[1].Name)
+		assert.True(t, labels.Less(0, 1))
+		assert.False(t, labels.Less(1, 0))
+	})
+
+	t.Run("equal priorities", func(t *testing.T) {
+		cat := Label{Name: "cat", Source: "location", Uncertainty: 59, Priority: 5}
+		dog := Label{Name: "dog", Source: "location", Uncertainty: 10, Priority: 5}
+		labels := Labels{cat, dog}
+		assert.Equal(t, "dog", labels[1].Name)
+		assert.False(t, labels.Less(0, 1))
+		assert.True(t, labels.Less(1, 0))
+	})
+}
+
+func TestLabels_Keywords(t *testing.T) {
+	cat := Label{Name: "cat", Source: "location", Uncertainty: 59, Priority: 5}
+	dog := Label{Name: "dog", Source: "location", Uncertainty: 10, Priority: 5}
+	labels := Labels{cat, dog}
+	result := labels.Keywords()
+	assert.Equal(t, "cat", result[0])
+	assert.Equal(t, "dog", result[1])
+
 }