Make testsuite work with LC_ALL=C

pytest.ini

@@ -26,6 +26,7 @@ markers =
     no_invalid_lines: Don't fail on unparseable lines in end2end tests
     issue2478: Tests which are broken on Windows with QtWebEngine, https://github.com/qutebrowser/qutebrowser/issues/2478
     fake_os: Fake utils.is_* to a fake operating system
+    unicode_locale: Tests which need an unicode locale to work
 qt_log_level_fail = WARNING
 qt_log_ignore =
     ^SpellCheck: .*

tests/conftest.py

@@ -63,6 +63,8 @@ def _apply_platform_markers(config, item):
         ('no_ci', 'CI' in os.environ, "Skipped on CI."),
         ('issue2478', utils.is_windows and config.webengine,
          "Broken with QtWebEngine on Windows"),
+        ('unicode_locale', sys.getfilesystemencoding() == 'ascii',
+         "Skipped because of ASCII locale"),
     ]
 
     for searched_marker, condition, default_reason in markers:

tests/end2end/features/history.feature

@@ -32,6 +32,7 @@ Feature: Page history
         Then the history should contain:
             http://localhost:(port)/data/title%20with%20spaces.html Test title
 
+    @unicode_locale
     Scenario: History item with umlauts
         When I open data/äöü.html
         Then the history should contain:

tests/unit/commands/test_userscripts.py

@@ -241,9 +241,8 @@ def test_unicode_error(caplog, qtbot, py_proc, runner):
             runner.store_html('')
 
     assert len(caplog.records) == 1
-    expected = ("Invalid unicode in userscript output: 'utf-8' codec can't "
-                "decode byte 0x80 in position 0: invalid start byte")
-    assert caplog.records[0].message == expected
+    expected = "Invalid unicode in userscript output: "
+    assert caplog.records[0].message.startswith(expected)
 
 
 @pytest.mark.fake_os('unknown')