nowplaying: Create an ArtistLabel

This label has properties for both Artist and Album Artist, and chooses
which to display based on the prefer-artist property and which tags have
been set.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

emmental/nowplaying/label.py

@@ -34,3 +34,30 @@ class Label(Gtk.Label):
         attrlist = Pango.AttrList.new()
         attrlist.insert(Pango.attr_size_new_absolute(self.size * Pango.SCALE))
         self.set_attributes(attrlist)
+
+
+class ArtistLabel(Label):
+    """A label that shows either Artist or Album Artist information."""
+
+    artist = GObject.Property(type=str)
+    album_artist = GObject.Property(type=str)
+    prefer_artist = GObject.Property(type=bool, default=True)
+
+    def __init__(self, **kwargs):
+        """Initialize the Artist Label."""
+        super().__init__(**kwargs)
+        self.connect("notify::artist", self.__notify)
+        self.connect("notify::album-artist", self.__notify)
+        self.connect("notify::prefer-artist", self.__notify)
+
+    def __notify(self, label, param) -> None:
+        if self.prefer_artist:
+            if len(self.artist) > 0:
+                self.text = self.artist
+            else:
+                self.text = self.album_artist
+        else:
+            if len(self.album_artist) > 0:
+                self.text = self.album_artist
+            else:
+                self.text = self.artist

tests/nowplaying/test_label.py

@@ -60,3 +60,55 @@ class TestLabel(unittest.TestCase):
                 self.label.size = size
                 self.assertEqual(self.label.get_attributes().to_string(),
                                  f"{expected} {size * Pango.SCALE}")
+
+
+class TestArtistLabel(unittest.TestCase):
+    """Test case for our Artist label."""
+
+    def setUp(self):
+        """Set up common variables."""
+        self.label = emmental.nowplaying.label.ArtistLabel(prefix="by ")
+
+    def test_init(self):
+        """Test that the artist label is set up properly."""
+        self.assertIsInstance(self.label, emmental.nowplaying.label.Label)
+        self.assertEqual(self.label.prefix, "by ")
+        self.assertEqual(self.label.artist, "")
+        self.assertEqual(self.label.album_artist, "")
+        self.assertTrue(self.label.prefer_artist)
+
+    def test_prefer_artist(self):
+        """Test situations where we want to use the artist property."""
+        self.label.prefer_artist = True
+
+        self.label.artist = "Test Artist"
+        self.assertEqual(self.label.get_text(), "by Test Artist")
+
+        self.label.album_artist = "Test Album Artist"
+        self.assertEqual(self.label.get_text(), "by Test Artist")
+
+        self.label.prefer_artist = False
+        self.assertEqual(self.label.get_text(), "by Test Album Artist")
+        self.label.prefer_artist = True
+        self.assertEqual(self.label.get_text(), "by Test Artist")
+
+        self.label.artist = ""
+        self.assertEqual(self.label.get_text(), "by Test Album Artist")
+
+    def test_prefer_album_artist(self):
+        """Test situations where we want to use the album artist property."""
+        self.label.prefer_artist = False
+
+        self.label.album_artist = "Test Album Artist"
+        self.assertEqual(self.label.get_text(), "by Test Album Artist")
+
+        self.label.artist = "Test Artist"
+        self.assertEqual(self.label.get_text(), "by Test Album Artist")
+
+        self.label.prefer_artist = True
+        self.assertEqual(self.label.get_text(), "by Test Artist")
+        self.label.prefer_artist = False
+        self.assertEqual(self.label.get_text(), "by Test Album Artist")
+
+        self.label.album_artist = ""
+        self.assertEqual(self.label.get_text(), "by Test Artist")