fastapi/tests/test_additional_responses_no_mutation.py

"""
Regression test: Ensure app-level responses with Union models and content/examples
don't accumulate duplicate $ref entries in anyOf arrays.
See https://github.com/fastapi/fastapi/pull/14463
"""

from fastapi import FastAPI
from pydantic import BaseModel

from fastapi.testclient import TestClient


class ModelA(BaseModel):
    a: str


class ModelB(BaseModel):
    b: str


app = FastAPI(
    responses={
        500: {
            'model': ModelA | ModelB,
            'content': {"application/json": {
                'examples': {"Case A": {"value": "a"}}
            }}
        }
    }
)


@app.get('/route1')
def route1():
    return "test"


@app.get('/route2')
def route2():
    return "test"


client = TestClient(app)


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {
        "openapi": "3.1.0",
        "info": {
            "title": "FastAPI",
            "version": "0.1.0"
        },
        "paths": {
            "/route1": {
                "get": {
                    "summary": "Route1",
                    "operationId": "route1_route1_get",
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {
                                "application/json": {
                                    "schema": {}
                                }
                            }
                        },
                        "500": {
                            "description": "Internal Server Error",
                            "content": {
                                "application/json": {
                                    "schema": {
                                        "anyOf": [
                                            {
                                                "$ref": "#/components/schemas/ModelA"
                                            },
                                            {
                                                "$ref": "#/components/schemas/ModelB"
                                            }
                                        ],
                                        "title": "Response 500 Route1 Route1 Get"
                                    },
                                    "examples": {
                                        "Case A": {
                                            "value": "a"
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            },
            "/route2": {
                "get": {
                    "summary": "Route2",
                    "operationId": "route2_route2_get",
                    "responses": {
                        "200": {
                            "description": "Successful Response",
                            "content": {
                                "application/json": {
                                    "schema": {}
                                }
                            }
                        },
                        "500": {
                            "description": "Internal Server Error",
                            "content": {
                                "application/json": {
                                    "schema": {
                                        "anyOf": [
                                            {
                                                "$ref": "#/components/schemas/ModelA"
                                            },
                                            {
                                                "$ref": "#/components/schemas/ModelB"
                                            }
                                        ],
                                        "title": "Response 500 Route2 Route2 Get"
                                    },
                                    "examples": {
                                        "Case A": {
                                            "value": "a"
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
        },
        "components": {
            "schemas": {
                "ModelA": {
                    "properties": {
                        "a": {
                            "type": "string",
                            "title": "A"
                        }
                    },
                    "type": "object",
                    "required": [
                        "a"
                    ],
                    "title": "ModelA"
                },
                "ModelB": {
                    "properties": {
                        "b": {
                            "type": "string",
                            "title": "B"
                        }
                    },
                    "type": "object",
                    "required": [
                        "b"
                    ],
                    "title": "ModelB"
                }
            }
        }
    }