Also redirect $HOME for QtWebEngine tests

See https://github.com/The-Compiler/qutebrowser/pull/1637#issuecomment-243043811

tests/helpers/fixtures.py

@@ -464,14 +464,17 @@ def data_tmpdir(monkeypatch, tmpdir):
 
 
 @pytest.fixture
-def redirect_xdg_data(data_tmpdir, monkeypatch):
-    """Set XDG_DATA_HOME to a temp location.
+def redirect_webengine_data(data_tmpdir, monkeypatch):
+    """Set XDG_DATA_HOME and HOME to a temp location.
 
     While data_tmpdir covers most cases by redirecting standarddir.data(), this
-    is not enough for places Qt references the data dir internally. For these,
-    we need to set the environment variable to redirect data access.
+    is not enough for places QtWebEngine references the data dir internally. For
+    these, we need to set the environment variable to redirect data access.
+
+    We also set HOME as in some places, the home directory is used directly...
     """
     monkeypatch.setenv('XDG_DATA_HOME', str(data_tmpdir))
+    monkeypatch.setenv('HOME', str(data_tmpdir))
 
 
 @pytest.fixture()

tests/unit/browser/test_tab.py

@@ -25,7 +25,7 @@ from qutebrowser.browser import browsertab
 from qutebrowser.keyinput import modeman
 from qutebrowser.utils import objreg
 
-pytestmark = pytest.mark.usefixtures('redirect_xdg_data')
+pytestmark = pytest.mark.usefixtures('redirect_webengine_data')
 
 try:
     from PyQt5.QtWebKitWidgets import QWebView

tests/unit/browser/webkit/test_qt_javascript.py

@@ -46,7 +46,7 @@ def test_element_js_webkit(webview, js_enabled, expected):
     assert result == expected
 
 
-@pytest.mark.usefixtures('redirect_xdg_data')
+@pytest.mark.usefixtures('redirect_webengine_data')
 @pytest.mark.parametrize('js_enabled, expected', [(True, 2.0), (False, 2.0)])
 def test_simple_js_webengine(callback_checker, webengineview, js_enabled,
                              expected):