Add more tests for the users repo and fix bugs they uncovered

src/infra/users.py

@@ -73,5 +73,6 @@ class UserRepoImpl(CRUDRepo[UserModel, User, UserDTO], UserRepo):
 
         try:
             self._hasher.verify(full_user.password_hash.expose_secret(), user.raw_password.expose_secret())
+            return full_user
         except VerifyMismatchError:
             return None

src/infra/users_test.py

@@ -5,12 +5,10 @@ from src.infra.users import UserRepoImpl
 from src.infra.db_test import mock_db
 import pytest
 
-DB = mock_db()
-
 
 @pytest.fixture
 def db():
-    return DB
+    return mock_db()
 
 
 @pytest.fixture
@@ -29,3 +27,15 @@ def users(repo: UserRepo):
 def test_getting_a_user_by_email(users: list[User], repo: UserRepo):
     assert repo.get_user_by_email('example@example.com') == users[0]
     assert repo.get_user_by_email('fred@example.com') is None
+
+
+def test_authenticating_as_a_user_can_succeed(users: list[User], repo: UserRepo):
+    assert repo.auth_as_user(UserDTO('example@example.com', SecretBox('hunter1'))) == users[0]
+
+
+def test_authenticating_fails_with_bad_password(users: list[User], repo: UserRepo):
+    assert repo.auth_as_user(UserDTO('example@example.com', SecretBox('something-wrong'))) is None
+
+
+def test_authenticating_fails_for_nonexistent_user(users: list[User], repo: UserRepo):
+    assert repo.auth_as_user(UserDTO('rando@example.com', SecretBox('test123'))) is None