✅ Add missing tests for code examples (#14569)

Co-authored-by: Sebastián Ramírez <tiangolo@gmail.com>
Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>
Co-authored-by: Nils-Hero Lindemann <nilsherolindemann@proton.me>

docs_src/dataclasses_/tutorial003_py310.py

@@ -0,0 +1,54 @@
+from dataclasses import field  # (1)
+
+from fastapi import FastAPI
+from pydantic.dataclasses import dataclass  # (2)
+
+
+@dataclass
+class Item:
+    name: str
+    description: str | None = None
+
+
+@dataclass
+class Author:
+    name: str
+    items: list[Item] = field(default_factory=list)  # (3)
+
+
+app = FastAPI()
+
+
+@app.post("/authors/{author_id}/items/", response_model=Author)  # (4)
+async def create_author_items(author_id: str, items: list[Item]):  # (5)
+    return {"name": author_id, "items": items}  # (6)
+
+
+@app.get("/authors/", response_model=list[Author])  # (7)
+def get_authors():  # (8)
+    return [  # (9)
+        {
+            "name": "Breaters",
+            "items": [
+                {
+                    "name": "Island In The Moon",
+                    "description": "A place to be playin' and havin' fun",
+                },
+                {"name": "Holy Buddies"},
+            ],
+        },
+        {
+            "name": "System of an Up",
+            "items": [
+                {
+                    "name": "Salt",
+                    "description": "The kombucha mushroom people's favorite",
+                },
+                {"name": "Pad Thai"},
+                {
+                    "name": "Lonely Night",
+                    "description": "The mostests lonliest nightiest of allest",
+                },
+            ],
+        },
+    ]