bdd: Make quteproc.set_setting work with quotes

This hopefully fixes editor BDD tests on Windows as the editor path is
now correctly quoted.

tests/integration/quteprocess.py

@@ -340,6 +340,8 @@ class QuteProc(testprocess.Process):
         return msg.message.split(' = ')[1]
 
     def set_setting(self, sect, opt, value):
+        # " in a value should be treated literally, so escape it
+        value = value.replace('"', '\\"')
         self.send_cmd(':set "{}" "{}" "{}"'.format(sect, opt, value))
         self.wait_for(category='config', message='Config option changed: *')
 

tests/integration/test_quteprocess.py

@@ -195,3 +195,13 @@ class TestClickElement:
 ])
 def test_xpath_escape(string, expected):
     assert quteprocess._xpath_escape(string) == expected
+
+
+@pytest.mark.parametrize('value', [
+    'foo',
+    'foo"bar',  # Make sure a " is preserved
+])
+def test_set(quteproc, value):
+    quteproc.set_setting('network', 'accept-language', value)
+    read_back = quteproc.get_setting('network', 'accept-language')
+    assert read_back == value