Remove HoverMove and reference issue about test failures.

securedrop_client/gui/widgets.py

@@ -1991,15 +1991,9 @@ def eventFilter(self, obj, event):
         if t == QEvent.MouseButtonPress:
             if event.button() == Qt.LeftButton:
                 self._on_left_click()
-        # HERE BE DRAGONS.
-        # The checks for "not self.downloading" in the following lines of code
-        # probably look strange. The obvious thing to do is to wrap such a
-        # check as a conditional. However, for reasons that are not entirely
-        # clear, this regularly caused random crashes when running the test
-        # suite (on Ubuntu 18.04, Python3.7). The following code expresses the
-        # same logic but without causing the random the crash of the test
-        # suite.
-        if (t == QEvent.HoverEnter or t == QEvent.HoverMove) and not self.downloading:
+        # See https://github.com/freedomofpress/securedrop-client/issues/835
+        # for context on code below.
+        if t == QEvent.HoverEnter and not self.downloading:
             self.download_button.setIcon(load_icon('download_file_hover.svg'))
         elif t == QEvent.HoverLeave and not self.downloading:
             self.download_button.setIcon(load_icon('download_file.svg'))

tests/gui/test_widgets.py

@@ -1500,11 +1500,6 @@ def test_FileWidget_event_handler_hover(mocker, session, source):
     fw.eventFilter(fw, test_event)
     assert fw.download_button.setIcon.call_count == 1
     fw.download_button.setIcon.reset_mock()
-    # Hover move
-    test_event = QEvent(QEvent.HoverMove)
-    fw.eventFilter(fw, test_event)
-    assert fw.download_button.setIcon.call_count == 1
-    fw.download_button.setIcon.reset_mock()
     # Hover leave
     test_event = QEvent(QEvent.HoverLeave)
     fw.eventFilter(fw, test_event)