Trigger editor signal on exit if content changed.

With the previous code, the editor could miss the final signal on a
save-and-exit. This is avoided by always running the file changed
handler on a successful exit, but only firing the signal if the content
actually changed (to avoid double-signalling).

qutebrowser/misc/editor.py

@@ -51,6 +51,7 @@ class ExternalEditor(QObject):
         self._proc = None
         self._remove_file = None
         self._watcher = QFileSystemWatcher(parent=self)
+        self._content = None
 
     def _cleanup(self):
         """Clean up temporary files after the editor closed."""
@@ -79,6 +80,8 @@ class ExternalEditor(QObject):
             # No error/cleanup here, since we already handle this in
             # on_proc_error.
             return
+        # do a final read to make sure we don't miss the last signal
+        self._on_file_changed(self._filename)
         self._cleanup()
 
     @pyqtSlot(QProcess.ProcessError)
@@ -128,8 +131,11 @@ class ExternalEditor(QObject):
             message.error("Failed to read back edited file: {}".format(e))
             return
         log.procs.debug("Read back: {}".format(text))
+        if self._content != text:
+            self._content = text
             self.file_updated.emit(text)
 
+
     def edit_file(self, filename):
         """Edit the file with the given filename."""
         self._filename = filename

tests/unit/misc/test_editor.py

@@ -129,9 +129,6 @@ class TestFileHandling:
             pytest.skip("File was still readable")
 
         with caplog.at_level(logging.ERROR):
-            with qtbot.wait_signal(editor._watcher.fileChanged):
-                with open(filename, 'w', encoding='utf-8') as f:
-                    f.write('unreadable')
             editor._proc.finished.emit(0, QProcess.NormalExit)
         assert not os.path.exists(filename)
         msg = message_mock.getmsg(usertypes.MessageLevel.error)
@@ -177,11 +174,30 @@ def test_modify(qtbot, editor, initial_text, edited_text):
         with open(editor._filename, 'w', encoding='utf-8') as f:
             f.write(edited_text)
 
+    with qtbot.assert_not_emitted(editor.file_updated):
         editor._proc.finished.emit(0, QProcess.NormalExit)
 
     assert blocker.args == [edited_text]
 
 
+def test_modify_multiple(qtbot, editor):
+    """Test that multiple saves all trigger file_updated."""
+    editor.edit('foo')
+
+    with qtbot.wait_signal(editor.file_updated) as blocker:
+        with open(editor._filename, 'w', encoding='utf-8') as f:
+            f.write('bar')
+    assert blocker.args == ['bar']
+
+    with qtbot.wait_signal(editor.file_updated) as blocker:
+        with open(editor._filename, 'w', encoding='utf-8') as f:
+            f.write('baz')
+    assert blocker.args == ['baz']
+
+    with qtbot.assert_not_emitted(editor.file_updated):
+        editor._proc.finished.emit(0, QProcess.NormalExit)
+
+
 @pytest.mark.parametrize('text, caret_position, result', [
     ('', 0, (1, 1)),
     ('a', 0, (1, 1)),