Add PACFetcher.fetch

Let's not try to download proxies during tests...

qutebrowser/browser/network/pac.py

@@ -247,8 +247,6 @@ class PACFetcher(QObject):
         self._pac_url = url
         self._manager = QNetworkAccessManager()
         self._manager.setProxy(QNetworkProxy(QNetworkProxy.NoProxy))
-        self._reply = self._manager.get(QNetworkRequest(url))
-        self._reply.finished.connect(self._finish)
         self._pac = None
         self._error_message = None
 
@@ -259,6 +257,11 @@ class PACFetcher(QObject):
     def __repr__(self):
         return utils.get_repr(self, url=self._pac_url, constructor=True)
 
+    def fetch(self):
+        """Fetch the proxy from the remote URL."""
+        self._reply = self._manager.get(QNetworkRequest(self._pac_url))
+        self._reply.finished.connect(self._finish)
+
     @pyqtSlot()
     def _finish(self):
         if self._reply.error() != QNetworkReply.NoError:

qutebrowser/utils/urlutils.py

@@ -637,7 +637,9 @@ def proxy_from_url(url):
 
     scheme = url.scheme()
     if scheme in ['pac+http', 'pac+https', 'pac+file']:
-        return pac.PACFetcher(url)
+        fetcher = pac.PACFetcher(url)
+        fetcher.fetch()
+        return fetcher
 
     types = {
         'http': QNetworkProxy.HttpProxy,

tests/unit/browser/webkit/network/test_pac.py

@@ -236,11 +236,12 @@ def fetcher_test(test_str):
     serve_thread.start()
     try:
         ready_event.wait()
-        res = pac.PACFetcher(QUrl("pac+http://127.0.0.1:8081"))
-        assert res.fetch_error() is None
+        fetcher = pac.PACFetcher(QUrl("pac+http://127.0.0.1:8081"))
+        fetcher.fetch()
+        assert fetcher.fetch_error() is None
     finally:
         serve_thread.join()
-    return res
+    return fetcher
 
 
 @pytest.mark.skipif(QT_VERSION_STR.startswith('5.7') and