Add test for union with discriminator

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Sebastián Ramírez 2025-12-12 14:58:57 +01:00
parent 1fcec88ad2
commit 10c551636e
1 changed files with 208 additions and 0 deletions

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# Ref: https://github.com/fastapi/fastapi/discussions/14495
from typing import Union
import pytest
from fastapi import FastAPI
from fastapi.testclient import TestClient
from inline_snapshot import snapshot
from pydantic import BaseModel
from typing_extensions import Annotated
from .utils import needs_pydanticv2
@pytest.fixture(name="client")
def client_fixture() -> TestClient:
from fastapi import Body
from pydantic import Discriminator, Tag
class Cat(BaseModel):
pet_type: str = "cat"
meows: int
class Dog(BaseModel):
pet_type: str = "dog"
barks: float
def get_pet_type(v):
if isinstance(v, dict):
return v.get("pet_type", "")
return getattr(v, "pet_type", "")
Pet = Annotated[
Union[Annotated[Cat, Tag("cat")], Annotated[Dog, Tag("dog")]],
Discriminator(get_pet_type),
]
app = FastAPI()
@app.post("/pet/assignment")
async def create_pet_assignment(pet: Pet = Body()):
return pet
@app.post("/pet/annotated")
async def create_pet_annotated(pet: Annotated[Pet, Body()]):
return pet
client = TestClient(app)
return client
@needs_pydanticv2
def test_union_body_discriminator_assignment(client: TestClient) -> None:
response = client.post("/pet/assignment", json={"pet_type": "cat", "meows": 5})
assert response.status_code == 200, response.text
assert response.json() == {"pet_type": "cat", "meows": 5}
@needs_pydanticv2
def test_union_body_discriminator_annotated(client: TestClient) -> None:
response = client.post("/pet/annotated", json={"pet_type": "dog", "barks": 3.5})
assert response.status_code == 200, response.text
assert response.json() == {"pet_type": "dog", "barks": 3.5}
@needs_pydanticv2
def test_openapi_schema(client: TestClient) -> None:
response = client.get("/openapi.json")
assert response.status_code == 200, response.text
assert response.json() == snapshot(
{
"openapi": "3.1.0",
"info": {"title": "FastAPI", "version": "0.1.0"},
"paths": {
"/pet/assignment": {
"post": {
"summary": "Create Pet Assignment",
"operationId": "create_pet_assignment_pet_assignment_post",
"requestBody": {
"content": {
"application/json": {
"schema": {
"anyOf": [
{"$ref": "#/components/schemas/Cat"},
{"$ref": "#/components/schemas/Dog"},
],
"title": "Pet",
}
}
},
"required": True,
},
"responses": {
"200": {
"description": "Successful Response",
"content": {"application/json": {"schema": {}}},
},
"422": {
"description": "Validation Error",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/HTTPValidationError"
}
}
},
},
},
}
},
"/pet/annotated": {
"post": {
"summary": "Create Pet Annotated",
"operationId": "create_pet_annotated_pet_annotated_post",
"requestBody": {
"content": {
"application/json": {
"schema": {
"oneOf": [
{"$ref": "#/components/schemas/Cat"},
{"$ref": "#/components/schemas/Dog"},
],
"title": "Pet",
}
}
},
"required": True,
},
"responses": {
"200": {
"description": "Successful Response",
"content": {"application/json": {"schema": {}}},
},
"422": {
"description": "Validation Error",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/HTTPValidationError"
}
}
},
},
},
}
},
},
"components": {
"schemas": {
"Cat": {
"properties": {
"pet_type": {
"type": "string",
"title": "Pet Type",
"default": "cat",
},
"meows": {"type": "integer", "title": "Meows"},
},
"type": "object",
"required": ["meows"],
"title": "Cat",
},
"Dog": {
"properties": {
"pet_type": {
"type": "string",
"title": "Pet Type",
"default": "dog",
},
"barks": {"type": "number", "title": "Barks"},
},
"type": "object",
"required": ["barks"],
"title": "Dog",
},
"HTTPValidationError": {
"properties": {
"detail": {
"items": {
"$ref": "#/components/schemas/ValidationError"
},
"type": "array",
"title": "Detail",
}
},
"type": "object",
"title": "HTTPValidationError",
},
"ValidationError": {
"properties": {
"loc": {
"items": {
"anyOf": [{"type": "string"}, {"type": "integer"}]
},
"type": "array",
"title": "Location",
},
"msg": {"type": "string", "title": "Message"},
"type": {"type": "string", "title": "Error Type"},
},
"type": "object",
"required": ["loc", "msg", "type"],
"title": "ValidationError",
},
}
},
}
)