如何为 FastAPI 应用程序编写 SQLAlchemy 测试装置

Question

我正在写一个FastAPI application that uses a SQLAlchemy database. I have copied the example from the FastAPI documentation，为了简洁起见简化了数据库模式。完整的源代码位于 post.

的底部

这行得通。我可以运行它与 uvicorn sql_app.main:app 并通过 Swagger 文档与数据库交互。当它运行s 时，它会在工作目录中创建一个 test.db。

现在我想添加一个单元测试。像这样。

from fastapi import status
from fastapi.testclient import TestClient
from pytest import fixture

from main import app


@fixture
def client() -> TestClient:
    return TestClient(app)


def test_fast_sql(client: TestClient):
    response = client.get("/users/")
    assert response.status_code == status.HTTP_200_OK
    assert response.json() == []

使用下面的源代码，这将工作目录中的 test.db 作为数据库。相反，我想为每个在测试结束时删除的单元测试创建一个新数据库。

我可以将全局 database.engine 和 database.SessionLocal 放入在运行时间创建的对象中，如下所示：

    class UserDatabase:
        def __init__(self, directory: Path):
            directory.mkdir(exist_ok=True, parents=True)
            sqlalchemy_database_url = f"sqlite:///{directory}/store.db"
            self.engine = create_engine(
                sqlalchemy_database_url, connect_args={"check_same_thread": False}
            )
            self.SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=self.engine)
            models.Base.metadata.create_all(bind=self.engine)

但我不知道如何与 main.get_db 一起工作，因为 Depends(get_db) 逻辑最终假设 database.engine 和 database.SessionLocal 是全球可用的。

我习惯于使用 Flask，它的单元测试工具可以为您处理所有这些。我自己也不知道怎么写。有人可以告诉我为了在这个框架中为每个单元测试生成一个新数据库我必须做的最小的改变吗？

简化的FastAPI/SQLAlchemy应用程序的完整源代码如下。

database.py

from sqlalchemy import create_engine
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

SQLALCHEMY_DATABASE_URL = "sqlite:///./test.db"

engine = create_engine(
    SQLALCHEMY_DATABASE_URL, connect_args={"check_same_thread": False}
)
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)

Base = declarative_base()

models.py

from sqlalchemy import Column, Integer, String

from database import Base


class User(Base):
    __tablename__ = "users"

    id = Column(Integer, primary_key=True, index=True)
    name = Column(String)
    age = Column(Integer)

schemas.py

from pydantic import BaseModel


class UserBase(BaseModel):
    name: str
    age: int


class UserCreate(UserBase):
    pass


class User(UserBase):
    id: int

    class Config:
        orm_mode = True

crud.py

from sqlalchemy.orm import Session

import schemas
import models


def get_user(db: Session, user_id: int):
    return db.query(models.User).filter(models.User.id == user_id).first()


def get_users(db: Session, skip: int = 0, limit: int = 100):
    return db.query(models.User).offset(skip).limit(limit).all()


def create_user(db: Session, user: schemas.UserCreate):
    db_user = models.User(name=user.name, age=user.age)
    db.add(db_user)
    db.commit()
    db.refresh(db_user)
    return db_user

main.py

from typing import List

from fastapi import Depends, FastAPI, HTTPException
from sqlalchemy.orm import Session

import schemas
import models
import crud
from database import SessionLocal, engine

models.Base.metadata.create_all(bind=engine)

app = FastAPI()


# Dependency
def get_db():
    try:
        db = SessionLocal()
        yield db
    finally:
        db.close()


@app.post("/users/", response_model=schemas.User)
def create_user(user: schemas.UserCreate, db: Session = Depends(get_db)):
    return crud.create_user(db=db, user=user)


@app.get("/users/", response_model=List[schemas.User])
def read_users(skip: int = 0, limit: int = 100, db: Session = Depends(get_db)):
    users = crud.get_users(db, skip=skip, limit=limit)
    return users


@app.get("/users/{user_id}", response_model=schemas.User)
def read_user(user_id: int, db: Session = Depends(get_db)):
    db_user = crud.get_user(db, user_id=user_id)
    if db_user is None:
        raise HTTPException(status_code=404, detail="User not found")
    return db_user

Answer 1

您需要在测试中覆盖 get_db 依赖项，请参阅 these docs。

像这样的灯具：

@fixture
def db_fixture() -> Session:
    raise NotImplementError()  # Make this return your temporary session

@fixture
def client(db_fixture) -> TestClient:

    def _get_db_override():
        return db_fixture

    app.dependency_overrides[get_db] = _get_db_override
    return TestClient(app)

如何为 FastAPI 应用程序编写 SQLAlchemy 测试装置

How do I write SQLAlchemy test fixtures for FastAPI applications

sqlalchemy

test-fixture

fastapi