Fix for TestMainWindowLoad::test_save.

- Add suffix to filename for file created by tempfile to be compatible with
enforcing 'ows' extension.

- Mocked `exec` method for QFileDialog now return True, because it was
never reach out branch `if dialog.exec():`.

Author: krystofair

orangecanvas/application/tests/test_mainwindow.py

@@ -1,7 +1,7 @@
 import io
 import os
 import tempfile
-from unittest.mock import patch
+from unittest.mock import patch, Mock
 
 from AnyQt.QtGui import QWhatsThisClickedEvent
 from AnyQt.QtWidgets import (
@@ -149,7 +149,7 @@ class TestMainWindowLoad(TestMainWindowBase):
 
     def setUp(self):
         super().setUp()
-        fd, filename = tempfile.mkstemp()
+        fd, filename = tempfile.mkstemp(suffix=".ows")
         self.file = os.fdopen(fd, "w+b")
         self.filename = filename
 
@@ -178,12 +178,16 @@ def test_save(self):
         w.current_document().setPath("")
 
         def exec(myself):
+            myself.setAcceptMode(QFileDialog.AcceptSave)
             myself.setOption(QFileDialog.DontUseNativeDialog)
             myself.setOption(QFileDialog.DontConfirmOverwrite)
             myself.selectFile(self.filename)
             myself.accept()
+            return True
 
-        with patch("AnyQt.QtWidgets.QFileDialog.exec", exec):
+        with (patch("AnyQt.QtWidgets.QFileDialog.exec", exec),
+              patch("AnyQt.QtWidgets.QMessageBox.question",
+                    new=Mock(return_value=QMessageBox.Yes))):
             w.save_scheme()
             self.assertTrue(os.path.samefile(w.current_document().path(), self.filename))