Move download_stub to helpers/fixtures

I am adding support for downloading dependant assets in
browser/greasemonkey and want to mock the download manager for testing.

tests/helpers/fixtures.py

@@ -523,3 +523,12 @@ class ModelValidator:
 @pytest.fixture
 def model_validator(qtmodeltester):
     return ModelValidator(qtmodeltester)
+
+
+@pytest.fixture
+def download_stub(win_registry, tmpdir, stubs):
+    """Register a FakeDownloadManager."""
+    stub = stubs.FakeDownloadManager(tmpdir)
+    objreg.register('qtnetwork-download-manager', stub)
+    yield
+    objreg.delete('qtnetwork-download-manager')

tests/helpers/stubs.py

@@ -22,6 +22,8 @@
 """Fake objects/stubs."""
 
 from unittest import mock
+import contextlib
+import shutil
 
 import attr
 from PyQt5.QtCore import pyqtSignal, QPoint, QProcess, QObject, QUrl
@@ -29,7 +31,7 @@ from PyQt5.QtNetwork import (QNetworkRequest, QAbstractNetworkCache,
                              QNetworkCacheMetaData)
 from PyQt5.QtWidgets import QCommonStyle, QLineEdit, QWidget, QTabBar
 
-from qutebrowser.browser import browsertab
+from qutebrowser.browser import browsertab, downloads
 from qutebrowser.utils import usertypes
 from qutebrowser.mainwindow import mainwindow
 
@@ -558,3 +560,47 @@ class HTTPPostStub(QObject):
     def post(self, url, data=None):
         self.url = url
         self.data = data
+
+
+class FakeDownloadItem(QObject):
+
+    """Mock browser.downloads.DownloadItem."""
+
+    finished = pyqtSignal()
+
+    def __init__(self, fileobj, name, parent=None):
+        super().__init__(parent)
+        self.fileobj = fileobj
+        self.name = name
+        self.successful = True
+
+
+class FakeDownloadManager:
+
+    """Mock browser.downloads.DownloadManager."""
+
+    def __init__(self, tmpdir):
+        self._tmpdir = tmpdir
+
+    @contextlib.contextmanager
+    def _open_fileobj(self, target):
+        """Ensure a DownloadTarget's fileobj attribute is available."""
+        if isinstance(target, downloads.FileDownloadTarget):
+            target.fileobj = open(target.filename, 'wb')
+            try:
+                yield target.fileobj
+            finally:
+                target.fileobj.close()
+        else:
+            yield target.fileobj
+
+    def get(self, url, target, **kwargs):
+        """Return a FakeDownloadItem instance with a fileobj.
+
+        The content is copied from the file the given url links to.
+        """
+        with self._open_fileobj(target):
+            download_item = FakeDownloadItem(target.fileobj, name=url.path())
+            with (self._tmpdir / url.path()).open('rb') as fake_url_file:
+                shutil.copyfileobj(fake_url_file, download_item.fileobj)
+        return download_item

tests/unit/browser/test_adblock.py

@@ -21,16 +21,13 @@
 import os
 import os.path
 import zipfile
-import shutil
 import logging
-import contextlib
 
 import pytest
 
-from PyQt5.QtCore import pyqtSignal, QUrl, QObject
+from PyQt5.QtCore import QUrl
 
-from qutebrowser.browser import adblock, downloads
-from qutebrowser.utils import objreg
+from qutebrowser.browser import adblock
 
 pytestmark = pytest.mark.usefixtures('qapp', 'config_tmpdir')
 
@@ -70,59 +67,6 @@ def basedir(fake_args):
     fake_args.basedir = None
 
 
-class FakeDownloadItem(QObject):
-
-    """Mock browser.downloads.DownloadItem."""
-
-    finished = pyqtSignal()
-
-    def __init__(self, fileobj, name, parent=None):
-        super().__init__(parent)
-        self.fileobj = fileobj
-        self.name = name
-        self.successful = True
-
-
-class FakeDownloadManager:
-
-    """Mock browser.downloads.DownloadManager."""
-
-    def __init__(self, tmpdir):
-        self._tmpdir = tmpdir
-
-    @contextlib.contextmanager
-    def _open_fileobj(self, target):
-        """Ensure a DownloadTarget's fileobj attribute is available."""
-        if isinstance(target, downloads.FileDownloadTarget):
-            target.fileobj = open(target.filename, 'wb')
-            try:
-                yield target.fileobj
-            finally:
-                target.fileobj.close()
-        else:
-            yield target.fileobj
-
-    def get(self, url, target, **kwargs):
-        """Return a FakeDownloadItem instance with a fileobj.
-
-        The content is copied from the file the given url links to.
-        """
-        with self._open_fileobj(target):
-            download_item = FakeDownloadItem(target.fileobj, name=url.path())
-            with (self._tmpdir / url.path()).open('rb') as fake_url_file:
-                shutil.copyfileobj(fake_url_file, download_item.fileobj)
-        return download_item
-
-
-@pytest.fixture
-def download_stub(win_registry, tmpdir):
-    """Register a FakeDownloadManager."""
-    stub = FakeDownloadManager(tmpdir)
-    objreg.register('qtnetwork-download-manager', stub)
-    yield
-    objreg.delete('qtnetwork-download-manager')
-
-
 def create_zipfile(directory, files, zipname='test'):
     """Return a path to a newly created zip file.