[FIX] Mosaic: clear when data is disconnected

Orange/widgets/visualize/owmosaic.py

@@ -384,6 +384,7 @@ def init_combos(self, data):
         for combo in self.attr_combos:
             combo.clear()
         if data is None:
+            self.color_model.set_domain(None)
             return
         for combo in self.attr_combos[1:]:
             combo.addItem("(None)")
@@ -440,6 +441,8 @@ def set_data(self, data):
             and len(self.data.domain.attributes) >= 1)
 
         if self.data is None:
+            self.discrete_data = None
+            self.init_combos(None)
             return
 
         self.color_model.set_domain(self.data.domain)

Orange/widgets/visualize/tests/test_owmosaic.py

@@ -77,6 +77,25 @@ def test_keyerror(self):
         data = data[0:1]
         self.send_signal(self.widget.Inputs.data, data)
 
+    def test_combos_and_mosaic(self):
+        """
+        Text in combos is wiped away when there is no data and mosaic disappears as well.
+        GH-2459
+        GH-2462
+        """
+        def assertCount(cb_color, cb_attr, areas):
+            self.assertEqual(len(self.widget.areas), areas)
+            self.assertEqual(self.widget.cb_attr_color.count(), cb_color)
+            for i, combo in enumerate(self.widget.attr_combos):
+                self.assertEqual(combo.count(), cb_attr[i])
+
+        data = Table("iris")
+        assertCount(1, [0, 0, 0, 0], 0)
+        self.send_signal(self.widget.Inputs.data, data)
+        assertCount(6, [5, 6, 6, 6], 16)
+        self.send_signal(self.widget.Inputs.data, None)
+        assertCount(1, [0, 0, 0, 0], 0)
+
 # Derive from WidgetTest to simplify creation of the Mosaic widget, although
 # we are actually testing the MosaicVizRank dialog and not the widget