make sure only premium user can create new mailbox via API

app/api/views/mailbox.py

@@ -41,6 +41,9 @@ def create_mailbox():
     user = g.user
     mailbox_email = sanitize_email(request.get_json().get("email"))
 
+    if not user.is_premium():
+        return jsonify(error=f"Only premium plan can add additional mailbox"), 400
+
     if not is_valid_email(mailbox_email):
         return jsonify(error=f"{mailbox_email} invalid"), 400
     elif mailbox_already_used(mailbox_email, user):

tests/api/test_mailbox.py

@@ -31,6 +31,20 @@ def test_create_mailbox(flask_client):
     assert r.json == {"error": "gmail.com invalid"}
 
 
+def test_create_mailbox_fail_for_free_user(flask_client):
+    user = login(flask_client)
+    user.trial_end = None
+    db.session.commit()
+
+    r = flask_client.post(
+        "/api/mailboxes",
+        json={"email": "mailbox@gmail.com"},
+    )
+
+    assert r.status_code == 400
+    assert r.json == {"error": "Only premium plan can add additional mailbox"}
+
+
 def test_delete_mailbox(flask_client):
     user = login(flask_client)