test: clean up JSON decode error tests per review feedback

tests/test_json_body_decode_error.py

@@ -22,7 +22,7 @@ class Item(BaseModel):
 
 @app.post("/items/")
 async def create_item(item: Item):
-    return item
+    return item  # pragma: no cover
 
 
 client = TestClient(app)
@@ -155,17 +155,3 @@ def test_json_decode_error_snippet_ellipsis(
     snippet = error["ctx"]["snippet"]
     assert snippet.startswith("...") == expected_starts_with_ellipsis
     assert snippet.endswith("...") == expected_ends_with_ellipsis
-
-
-def test_successful_item_creation():
-    response = client.post(
-        "/items/",
-        json={"name": "Test Item", "price": 19.99,
-              "description": "A test item"},
-    )
-
-    assert response.status_code == 200
-    data = response.json()
-    assert data["name"] == "Test Item"
-    assert data["price"] == 19.99
-    assert data["description"] == "A test item"