Add test capturing expectation that sys.argv need not be initialized …

…as indicated by the Python docs and might in fact be empty or uninitialized or not a list. Ref #445.

tests/test_integration.py

@@ -0,0 +1,19 @@
+import sys
+import subprocess
+
+import pytest
+
+
+argv_manipulations = [
+    'del sys.argv',
+    'sys.argv = []',
+    'sys.argv = None',
+]
+
+
+@pytest.mark.xfail(reason="#445")
+@pytest.mark.parametrize('argv', argv_manipulations)
+def test_argv(argv):
+    code = f'import sys; {argv}; import keyring'
+    cmd = [sys.executable, '-c', code]
+    assert not subprocess.check_output(cmd, stderr=subprocess.STDOUT)