sidebar: Create a ChildModel list model

This will be used to display the children of some of our playlists.

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

sidebar/model.py

@@ -0,0 +1,16 @@
+# Copyright 2021 (c) Anna Schumaker.
+from gi.repository import GObject
+from gi.repository import Gio
+
+class ChildModel(GObject.GObject, Gio.ListModel):
+    def __init__(self, parent):
+        GObject.GObject.__init__(self)
+        self.parent = parent
+        self.parent.connect("children-changed", self.children_changed)
+
+    def do_get_item_type(self): return GObject.TYPE_PYOBJECT
+    def do_get_n_items(self):   return self.parent.get_n_children()
+    def do_get_item(self, n):   return self.parent.get_child(n)
+
+    def children_changed(self, item, pos, rm, add):
+        self.emit("items-changed", pos, rm, add)

sidebar/test_model.py

@@ -0,0 +1,35 @@
+# Copyright 2021 (c) Anna Schumaker.
+import datetime
+import db
+import unittest
+from gi.repository import GObject
+from gi.repository import Gio
+from . import model
+
+class TestChildModel(unittest.TestCase):
+    def items_changed(self, table, pos, rm, add):
+        self.changed = (pos, rm, add)
+
+    def setUp(self):
+        db.reset()
+
+    def test_init(self):
+        artist = db.artist.Table.find("Test Artist", "Test Sort")
+        child = model.ChildModel(artist)
+
+        self.assertIsInstance(child, GObject.GObject)
+        self.assertIsInstance(child, Gio.ListModel)
+
+        self.assertEqual(child.parent, artist)
+        self.assertEqual(child.get_item_type(), GObject.TYPE_PYOBJECT)
+        self.assertEqual(child.get_n_items(), 0)
+
+    def test_children(self):
+        artist = db.artist.Table.find("Test Artist", "Test Sort")
+        child = model.ChildModel(artist)
+        child.connect("items-changed", self.items_changed)
+
+        album = artist.find_album("Test Album", datetime.date.today())
+        self.assertEqual(child.get_n_items(), 1)
+        self.assertEqual(child.get_item(0), album)
+        self.assertEqual(self.changed, (0, 0, 1))