diff --git a/tests/conftest.py b/tests/conftest.py
index 037165d9..999ef437 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -273,22 +273,6 @@ def mock_user_db(
     return MockUserDatabase(UserDB)
 
 
-@pytest.fixture
-def get_mock_user_db(mock_user_db):
-    def _get_mock_user_db():
-        yield mock_user_db
-
-    return _get_mock_user_db
-
-
-@pytest.fixture
-def get_user_manager(get_mock_user_db, validate_password):
-    def _get_user_manager(user_db=Depends(get_mock_user_db)):
-        yield UserManager(UserDB, user_db, validate_password)
-
-    return _get_user_manager
-
-
 @pytest.fixture
 def mock_user_db_oauth(
     user_oauth,
@@ -355,6 +339,14 @@ def mock_user_db_oauth(
     return MockUserDatabase(UserDBOAuth)
 
 
+@pytest.fixture
+def get_mock_user_db(mock_user_db):
+    def _get_mock_user_db():
+        yield mock_user_db
+
+    return _get_mock_user_db
+
+
 @pytest.fixture
 def get_mock_user_db_oauth(mock_user_db_oauth):
     def _get_mock_user_db_oauth():
@@ -363,6 +355,19 @@ def get_mock_user_db_oauth(mock_user_db_oauth):
     return _get_mock_user_db_oauth
 
 
+@pytest.fixture
+def user_manager(mock_user_db, validate_password):
+    return UserManager(UserDB, mock_user_db, validate_password)
+
+
+@pytest.fixture
+def get_user_manager(get_mock_user_db, validate_password):
+    def _get_user_manager(user_db=Depends(get_mock_user_db)):
+        yield UserManager(UserDB, user_db, validate_password)
+
+    return _get_user_manager
+
+
 @pytest.fixture
 def get_user_manager_oauth(get_mock_user_db_oauth, validate_password):
     def _get_user_manager_oauth(user_db=Depends(get_mock_user_db_oauth)):
diff --git a/tests/test_authentication_base.py b/tests/test_authentication_base.py
index 3f971a95..0ca6746c 100644
--- a/tests/test_authentication_base.py
+++ b/tests/test_authentication_base.py
@@ -12,9 +12,9 @@ def base_authentication():
 @pytest.mark.authentication
 class TestAuthenticate:
     @pytest.mark.asyncio
-    async def test_not_implemented(self, base_authentication, mock_user_db):
+    async def test_not_implemented(self, base_authentication, user_manager):
         with pytest.raises(NotImplementedError):
-            await base_authentication(None, mock_user_db)
+            await base_authentication(None, user_manager)
 
 
 @pytest.mark.authentication
diff --git a/tests/test_authentication_cookie.py b/tests/test_authentication_cookie.py
index b9d9ed53..1fbbba95 100644
--- a/tests/test_authentication_cookie.py
+++ b/tests/test_authentication_cookie.py
@@ -52,37 +52,46 @@ def test_default_name(cookie_authentication: CookieAuthentication):
 class TestAuthenticate:
     @pytest.mark.asyncio
     async def test_missing_token(
-        self, mock_user_db, cookie_authentication: CookieAuthentication
+        self, user_manager, cookie_authentication: CookieAuthentication
     ):
-        authenticated_user = await cookie_authentication(None, mock_user_db)
+        authenticated_user = await cookie_authentication(None, user_manager)
         assert authenticated_user is None
 
     @pytest.mark.asyncio
     async def test_invalid_token(
-        self, mock_user_db, cookie_authentication: CookieAuthentication
+        self, user_manager, cookie_authentication: CookieAuthentication
     ):
-        authenticated_user = await cookie_authentication("foo", mock_user_db)
+        authenticated_user = await cookie_authentication("foo", user_manager)
         assert authenticated_user is None
 
     @pytest.mark.asyncio
     async def test_valid_token_missing_user_payload(
-        self, mock_user_db, token, cookie_authentication: CookieAuthentication
+        self, user_manager, token, cookie_authentication: CookieAuthentication
     ):
-        authenticated_user = await cookie_authentication(token(), mock_user_db)
+        authenticated_user = await cookie_authentication(token(), user_manager)
         assert authenticated_user is None
 
     @pytest.mark.asyncio
     async def test_valid_token_invalid_uuid(
-        self, mock_user_db, token, cookie_authentication: CookieAuthentication
+        self, user_manager, token, cookie_authentication: CookieAuthentication
     ):
-        authenticated_user = await cookie_authentication(token("foo"), mock_user_db)
+        authenticated_user = await cookie_authentication(token("foo"), user_manager)
+        assert authenticated_user is None
+
+    @pytest.mark.asyncio
+    async def test_valid_token_not_existing_user(
+        self, user_manager, token, cookie_authentication: CookieAuthentication
+    ):
+        authenticated_user = await cookie_authentication(
+            token("d35d213e-f3d8-4f08-954a-7e0d1bea286f"), user_manager
+        )
         assert authenticated_user is None
 
     @pytest.mark.asyncio
     async def test_valid_token(
-        self, mock_user_db, token, user, cookie_authentication: CookieAuthentication
+        self, user_manager, token, user, cookie_authentication: CookieAuthentication
     ):
-        authenticated_user = await cookie_authentication(token(user.id), mock_user_db)
+        authenticated_user = await cookie_authentication(token(user.id), user_manager)
         assert authenticated_user is not None
         assert authenticated_user.id == user.id
 
diff --git a/tests/test_authentication_jwt.py b/tests/test_authentication_jwt.py
index 21ff11f3..971a79c4 100644
--- a/tests/test_authentication_jwt.py
+++ b/tests/test_authentication_jwt.py
@@ -32,27 +32,36 @@ def test_default_name(jwt_authentication):
 @pytest.mark.authentication
 class TestAuthenticate:
     @pytest.mark.asyncio
-    async def test_missing_token(self, jwt_authentication, mock_user_db):
-        authenticated_user = await jwt_authentication(None, mock_user_db)
+    async def test_missing_token(self, jwt_authentication, user_manager):
+        authenticated_user = await jwt_authentication(None, user_manager)
         assert authenticated_user is None
 
     @pytest.mark.asyncio
-    async def test_invalid_token(self, jwt_authentication, mock_user_db):
-        authenticated_user = await jwt_authentication("foo", mock_user_db)
+    async def test_invalid_token(self, jwt_authentication, user_manager):
+        authenticated_user = await jwt_authentication("foo", user_manager)
         assert authenticated_user is None
 
     @pytest.mark.asyncio
     async def test_valid_token_missing_user_payload(
-        self, jwt_authentication, mock_user_db, token
+        self, jwt_authentication, user_manager, token
     ):
-        authenticated_user = await jwt_authentication(token(), mock_user_db)
+        authenticated_user = await jwt_authentication(token(), user_manager)
         assert authenticated_user is None
 
     @pytest.mark.asyncio
     async def test_valid_token_invalid_uuid(
-        self, jwt_authentication, mock_user_db, token
+        self, jwt_authentication, user_manager, token
     ):
-        authenticated_user = await jwt_authentication(token("foo"), mock_user_db)
+        authenticated_user = await jwt_authentication(token("foo"), user_manager)
+        assert authenticated_user is None
+
+    @pytest.mark.asyncio
+    async def test_valid_token_not_existing_user(
+        self, jwt_authentication, user_manager, token
+    ):
+        authenticated_user = await jwt_authentication(
+            token("d35d213e-f3d8-4f08-954a-7e0d1bea286f"), user_manager
+        )
         assert authenticated_user is None
 
     @pytest.mark.asyncio