-        bmp = images.getTest2Bitmap()
-        mask = wxMaskColour(bmp, wxBLUE)
-        bmp.SetMask(mask)
+        if 0:  # a test case for catching wxPyAssertionError
+
+            #wxGetApp().SetAssertMode(wxPYAPP_ASSERT_SUPPRESS)
+            #wxGetApp().SetAssertMode(wxPYAPP_ASSERT_EXCEPTION)
+            #wxGetApp().SetAssertMode(wxPYAPP_ASSERT_DIALOG)
+            #wxGetApp().SetAssertMode(wxPYAPP_ASSERT_EXCEPTION | wxPYAPP_ASSERT_DIALOG)
+
+            try:
+                bmp = wxBitmap("nosuchfile.bmp", wxBITMAP_TYPE_BMP)
+                mask = wxMaskColour(bmp, wxBLUE)
+            except wxPyAssertionError:
+                self.log.write("Caught wxPyAssertionError!  I will fix the problem.\n")
+                bmp = images.getTest2Bitmap()
+                mask = wxMaskColour(bmp, wxBLUE)
+        else:
+            bmp = images.getTest2Bitmap()
+            mask = wxMaskColour(bmp, wxBLUE)