Add tests for greasemonkey worldid in webenginetab.

Adds a new file for tests relating to WebEngineTab, it looks a little
sparse right now but I'm sure there will be more soon.

Tests that scripts with invalid world IDs are rejected appropriately and
the ones with valid world IDs aren't rejected.

The `FakeWidget` thing is so `sip.isdeleted` didn't complain about being
passed the wrong type.

tests/unit/browser/webengine/test_webenginetab.py

@@ -0,0 +1,107 @@
+# vim: ft=python fileencoding=utf-8 sts=4 sw=4 et:
+
+# Copyright 2018 Florian Bruhin (The Compiler) <mail@qutebrowser.org>
+#
+# This file is part of qutebrowser.
+#
+# qutebrowser is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# qutebrowser is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with qutebrowser.  If not, see <http://www.gnu.org/licenses/>.
+
+"""Test webenginetab."""
+
+from unittest import mock
+import logging
+
+from PyQt5.QtCore import QObject
+from PyQt5.QtWebEngineWidgets import QWebEnginePage, QWebEngineScriptCollection
+import pytest
+
+from qutebrowser.browser.webengine.webenginetab import _WebEngineScripts
+from qutebrowser.browser.greasemonkey import GreasemonkeyScript
+
+pytestmark = pytest.mark.usefixtures('greasemonkey_manager')
+
+
+class TestWebengineScripts:
+    """Test the _WebEngineScripts utility class."""
+
+    class FakeWidget(QObject):
+        """Fake widget for _WebengineScripts to use."""
+
+        def __init__(self, *args, **kwargs):
+            super().__init__(*args, **kwargs)
+            self.scripts = []
+            self.page = mock.create_autospec(QWebEnginePage)
+            self.scripts_mock = mock.create_autospec(
+                QWebEngineScriptCollection
+            )
+            self.scripts_mock.toList.return_value = self.scripts
+            self.page.return_value.scripts.return_value = self.scripts_mock
+
+    def test_greasemonkey_undefined_world(self, fake_web_tab, caplog):
+        """Make sure scripts with non-existent worlds are rejected."""
+        uut = _WebEngineScripts(fake_web_tab)
+        uut._widget = self.FakeWidget()
+        scripts = [
+            GreasemonkeyScript([('qute-js-world', 'Mars')], None)
+        ]
+
+        with caplog.at_level(logging.ERROR, 'greasemonkey'):
+            uut._inject_greasemonkey_scripts(scripts)
+
+        assert len(caplog.records) == 1
+        msg = caplog.records[0].message
+        assert "has invalid value for '@qute-js-world': Mars" in msg
+        uut._widget.scripts_mock.insert.assert_not_called()
+
+    @pytest.mark.parametrize("worldid", [
+        -1, 257
+    ])
+    def test_greasemonkey_out_of_range_world(self, worldid,
+                                             fake_web_tab, caplog):
+        """Make sure scripts with out-of-range worlds are rejected."""
+        uut = _WebEngineScripts(fake_web_tab)
+        uut._widget = self.FakeWidget()
+        scripts = [
+            GreasemonkeyScript([('qute-js-world', worldid)], None)
+        ]
+
+        with caplog.at_level(logging.ERROR, 'greasemonkey'):
+            uut._inject_greasemonkey_scripts(scripts)
+
+        assert len(caplog.records) == 1
+        msg = caplog.records[0].message
+        assert "has invalid value for '@qute-js-world': " in msg
+        assert "should be between 0 and" in msg
+        uut._widget.scripts_mock.insert.assert_not_called()
+
+    @pytest.mark.parametrize("worldid", [
+        0, 10
+    ])
+    def test_greasemonkey_good_worlds_are_passed(self, worldid,
+                                                 fake_web_tab, caplog):
+        """Make sure scripts with valid worlds have it set."""
+        uut = _WebEngineScripts(fake_web_tab)
+        uut._widget = self.FakeWidget()
+        scripts = [
+            GreasemonkeyScript(
+                [('name', 'foo'), ('qute-js-world', worldid)], None
+            )
+        ]
+
+        with caplog.at_level(logging.ERROR, 'greasemonkey'):
+            uut._inject_greasemonkey_scripts(scripts)
+
+        calls = uut._widget.scripts_mock.insert.call_args_list
+        assert len(calls) == 1
+        assert calls[0][0][0].worldId() == worldid