lib: Give Tags functions for saving and restoring state

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

lib/tag.py

@@ -6,12 +6,21 @@ class Tag:
         self.tracks = [ ]
         self.widgets = None
 
+    def __getstate__(self):
+        return { "name"   : self.name,
+                 "tracks" : self.tracks }
+
     def __len__(self):
         return len(self.tracks)
 
     def __lt__(self, rhs):
         return self.name < rhs.name
 
+    def __setstate__(self, state):
+        self.name    = state["name"]
+        self.tracks  = state["tracks"]
+        self.widgets = None
+
     def add_track(self, track):
         self.tracks.append(track)
 

lib/test_tag.py

@@ -23,6 +23,21 @@ class TestTag(unittest.TestCase):
         self.assertFalse(b < a)
         self.assertFalse(a < a)
 
+    def test_tag_state(self):
+        t = tag.Tag("test")
+        t.tracks = [ 1, 2, 3, 4, 5 ]
+
+        state = t.__getstate__()
+        self.assertEqual(set(state.keys()), set([ "name", "tracks" ]))
+        self.assertEqual(state["name"], "test")
+        self.assertEqual(state["tracks"], [ 1, 2, 3, 4, 5 ])
+
+        t.__dict__.clear()
+        t.__setstate__(state)
+        self.assertEqual(t.name, "test")
+        self.assertEqual(t.tracks, [ 1, 2, 3, 4, 5 ])
+        self.assertEqual(t.widgets, None)
+
     def test_tag_add_track(self):
         t = tag.Tag("test")
         t.add_track(1)