scanner: Set initial ProgressBar visibility based on queue length

ProgressBars might be created after tasks have been pushed onto the
queue. Instead of setting initial visibility to False unconditionally,
we can check if queue length is greater than 1

Fixes: Issue #9 (Fix ProgressBar initial visibility)
Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

scanner/test_widgets.py

@@ -29,6 +29,7 @@ class TestScannerProgressBar(unittest.TestCase):
 
         for i in range(3): q.push(FakeTask())
         self.assertTrue(pb.get_visible())
+        self.assertTrue(widgets.ProgressBar(q).get_visible())
 
         for i in [ 1, 2, 0 ]:
             q.run()

scanner/widgets.py

@@ -16,7 +16,7 @@ class ProgressBar(Gtk.ProgressBar):
 
         self.set_valign(Gtk.Align.CENTER)
         self.set_hexpand(True)
-        self.set_visible(False)
+        self.set_visible(len(queue.tasks) > 0)
 
     def on_task_pushed(self, queue, task):
         self.set_visible(True)