Add simple test for Fake login

tests/test_mijnbibliotheek.py

@@ -0,0 +1,53 @@
+import io
+from typing import BinaryIO
+
+import pytest
+
+from mijnbib import MijnBibliotheek
+from mijnbib.plugin_errors import AuthenticationError
+
+
+class FakeMechanizeBrowser:
+    def __init__(self, form_response: str) -> None:
+        self._form_response = form_response.encode("utf8")
+
+    def __setitem__(self, key, value):
+        pass
+
+    def open(self, url) -> BinaryIO:
+        return io.BytesIO(b"some response html")
+
+    def select_form(self, *args, **kwargs):
+        pass
+
+    def submit(self, *args, **kwargs) -> BinaryIO:
+        return io.BytesIO(self._form_response)
+
+
+def test_login_ok():
+    mb = MijnBibliotheek("user", "pwd", "city")
+    mb._br = FakeMechanizeBrowser(form_response="Profiel")  # type: ignore
+    mb.login()
+
+    assert mb._logged_in
+
+
+def test_login_fails():
+    mb = MijnBibliotheek("user", "pwd", "city")
+    mb._br = FakeMechanizeBrowser(form_response="whatever")  # type: ignore
+
+    with pytest.raises(AuthenticationError, match=r".*Login not accepted.*"):
+        mb.login()
+    assert mb._logged_in is False
+
+
+def test_login_fails_because_of_privacy():
+    mb = MijnBibliotheek("user", "pwd", "city")
+    mb._br = FakeMechanizeBrowser(form_response="privacyverklaring is gewijzigd")  # type: ignore
+
+    with pytest.raises(
+        AuthenticationError,
+        match=r".*Login not accepted \(likely need to accept privacy statement again\).*",
+    ):
+        mb.login()
+    assert mb._logged_in is False