Fix exception occuring on Admin demotion (#1799)

* Fix an exception that occurred when demoting an Admin user
* Fix the response from the above request from returning a list instead of a dict
* Closes #1794

tests/api/v1/users/test_users.py

@@ -1,7 +1,7 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-from tests.helpers import create_ctfd, destroy_ctfd, login_as_user
+from tests.helpers import create_ctfd, destroy_ctfd, login_as_user, register_user
 
 
 def test_api_self_ban():
@@ -15,3 +15,23 @@ def test_api_self_ban():
             assert resp["success"] == False
             assert resp["errors"] == {"id": "You cannot ban yourself"}
     destroy_ctfd(app)
+
+
+def test_api_modify_user_type():
+    """Can a user patch /api/v1/users/<user_id> to promote a user to admin and demote them to user"""
+    app = create_ctfd()
+    with app.app_context():
+        register_user(app)
+        with login_as_user(app, "admin") as client:
+            r = client.patch("/api/v1/users/2", json={"type": "admin"})
+            assert r.status_code == 200
+            user_data = r.get_json()["data"]
+            assert user_data["name"] == "user"
+            assert user_data["type"] == "admin"
+
+            r = client.patch("/api/v1/users/2", json={"type": "user"})
+            assert r.status_code == 200
+            user_data = r.get_json()["data"]
+            assert user_data["name"] == "user"
+            assert user_data["type"] == "user"
+    destroy_ctfd(app)