From 404393b3a7570409dd8f463c2129209a2072d6ea Mon Sep 17 00:00:00 2001
From: Marios Hadjiantonis <mhadjiantonis@gmail.com>
Date: Sun, 23 Aug 2026 20:37:55 +0200
Subject: [PATCH] Reapply "Add username pattern validation"

This reverts commit bba13d72c156b578d8fa31ee477e29fa3eacb2d0.
---
 jsonplaceholder_api_proxy/users/models.py |  2 +-
 tests/users/test_api_router.py            | 35 +++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/jsonplaceholder_api_proxy/users/models.py b/jsonplaceholder_api_proxy/users/models.py
index fbd87b5..434c371 100644
--- a/jsonplaceholder_api_proxy/users/models.py
+++ b/jsonplaceholder_api_proxy/users/models.py
@@ -22,7 +22,7 @@ class Company(BaseModel):
         business_slogan: Annotated[str, Field(alias="bs")]
 
     name: str
-    username: str
+    username: Annotated[str, Field(pattern=r"^[A-Za-z][A-Za-z0-9_.]{0,19}$")]
     email: EmailStr
     phone: str
     address: Address
diff --git a/tests/users/test_api_router.py b/tests/users/test_api_router.py
index d50387e..a7ddb50 100644
--- a/tests/users/test_api_router.py
+++ b/tests/users/test_api_router.py
@@ -159,6 +159,41 @@ async def test_create_user_invalid_email(client: tuple[TestClient, AsyncMockType
     assert response.status_code == status.HTTP_422_UNPROCESSABLE_CONTENT
 
 
+@pytest.mark.asyncio
+async def test_create_user_invalid_username(client: tuple[TestClient, AsyncMockType]):
+    """Test POST /users with invalid email"""
+    test_client, _ = client
+
+    invalid_usernames = [
+        "0test",
+        "test+example",
+        "test" * 10,
+    ]
+    for username in invalid_usernames:
+        payload: dict[str, Any] = {
+            "name": "John Doe",
+            "username": username,
+            "email": "test@example.com",
+            "phone": "1-770-736-8031",
+            "address": {
+                "street": "Kulas Light",
+                "suite": "Apt. 556",
+                "city": "Gwenborough",
+                "zipcode": "92998-3874",
+                "geo": {"lat": 37.7749, "lng": -122.4194},
+            },
+            "company": {
+                "name": "Romaguera-Crona",
+                "catchPhrase": "Multi-layered client-server neural-net",
+                "bs": "harness real-time e-markets",
+            },
+        }
+
+        response = test_client.post("/users", json=payload)
+
+        assert response.status_code == status.HTTP_422_UNPROCESSABLE_CONTENT
+
+
 @pytest.mark.asyncio
 async def test_create_user_missing_required_field(
     client: tuple[TestClient, AsyncMockType],