FastAPI（43）- 基于 pytest + requests 进行单元测试

FastAPI 的单元测试

• 对于服务端来说，通常会对功能进行单元测试，也称白盒测试
• FastAPI 集成了第三方库，让我们可以快捷的编写单元测试
• FastAPI 的单元测试是基于 Pytest + Request 的

Pytest 学习

https://www.cnblogs.com/poloyy/tag/Pytest/

TestClient 简单的栗子

#!usr/bin/env python
# -*- coding:utf-8 _*-
"""
# author: 小菠萝测试笔记
# blog:  https://www.cnblogs.com/poloyy/
# time: 2021/9/29 10:55 下午
# file: 37_pytest.py
"""
import uvicorn
from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()

@app.get("/")
async def read_main():
    return {"msg": "Hello World"}

# 声明一个 TestClient，把 FastAPI() 实例对象传进去
client = TestClient(app)

# 测试用
def test_read_main():
    # 请求 127.0.0.1:8080/
    response = client.get("/")
    assert response.status_code == 200
    assert response.json() == {"msg": "Hello World"}

if __name__ == '__main__':
    uvicorn.run(app="37_pytest:app", reload=True, host="127.0.0.1", port=8080)

在该文件夹下的命令行敲

pytest 37_pytest.py

运行结果

TestClient 的源码解析

继承了 requests 库的 Session

所以可以像使用 requests 库一样使用 TestClient，拥有 requests 所有方法、属性

重写了 Session.requests 方法

重写了 requests 方法，不过只是加了一句 url = urljoin(self.base_url, url) url 拼接代码，还有给函数参数都加了类型指示，更加完善啦~

自定义 websocket 连接方法

后面学到 webSocket 再详细讲他

重写了 __enter__、__exit__ 方法

• Session 的这两个方法还是比较简陋的，TestClient 做了一次重写，主要是为了添加异步的功能（异步测试后面详解，这篇举栗子的都是普通函数 def）
• 前面讲过有 __enter__、__exit__ 方法的对象都是上下文管理器，可以用 with .. as ..语句来调用上下文管理器哦

.get() 方法

上面代码 client.get()，直接调用的就是 Session 提供的 get() 方法啦！

复杂的测试场景

服务端

#!usr/bin/env python
# -*- coding:utf-8 _*-
"""
# author: 小菠萝测试笔记
# blog:  https://www.cnblogs.com/poloyy/
# time: 2021/9/29 10:55 下午
# file: s37_pytest.py
"""
import uvicorn
from fastapi import FastAPI
from fastapi.testclient import TestClient

app = FastAPI()

@app.get("/")
async def read_main():
    return {"msg": "Hello World"}

# 声明一个 TestClient，把 FastAPI() 实例对象传进去
client = TestClient(app)

# 测试用
def test_read_main():
    # 请求 127.0.0.1:8080/
    response = client.get("/")
    assert response.status_code == 200
    assert response.json() == {"msg": "Hello World"}

from typing import Optional

from fastapi import FastAPI, Header, HTTPException
from pydantic import BaseModel

# 模拟真实 token
fake_secret_token = "coneofsilence"

# 模拟真实数据库
fake_db = {
    "foo": {"id": "foo", "title": "Foo", "description": "There goes my hero"},
    "bar": {"id": "bar", "title": "Bar", "description": "The bartenders"},
}

app = FastAPI()

class Item(BaseModel):
    id: str
    title: str
    description: Optional[str] = None

# 接口一：查询数据
@app.get("/items/{item_id}", response_model=Item)
async def read_main(item_id: str, x_token: str = Header(...)):
    # 1、校验 token 失败
    if x_token != fake_secret_token:
        raise HTTPException(status_code=400, detail="x-token 错误")

    # 2、若数据库没有对应数据
    if item_id not in fake_db:
        raise HTTPException(status_code=404, detail="找不到 item_id")
    # 3、找到数据则返回
    return fake_db[item_id]

# 接口二：创建数据
@app.post("/items/", response_model=Item)
async def create_item(item: Item, x_token: str = Header(...)):
    # 1、校验 token 失败
    if x_token != fake_secret_token:
        raise HTTPException(status_code=400, detail="x-token 错误")

    # 2、若数据库已经存在相同 id 的数据
    if item.id in fake_db:
        raise HTTPException(status_code=400, detail="找不到 item_id")

    # 3、添加数据到数据库
    fake_db[item.id] = item

    # 4、返回添加的数据
    return item

if __name__ == '__main__':
    uvicorn.run(app="s37_test_pytest:app", reload=True, host="127.0.0.1", port=8080)

单元测试

#!usr/bin/env python
# -*- coding:utf-8 _*-
"""
# author: 小菠萝测试笔记
# blog:  https://www.cnblogs.com/poloyy/
# time: 2021/9/29 10:55 下午
# file: s37_pytest.py
"""
from fastapi.testclient import TestClient
from .s37_test_pytest import app

client = TestClient(app)

def test_read_item():
    expect = {"id": "foo", "title": "Foo", "description": "There goes my hero"}
    headers = {"x-token": "coneofsilence"}
    resp = client.get("/items/foo", headers=headers)
    assert resp.status_code == 200
    assert resp.json() == expect

def test_read_item_error_header():
    expect = {"detail": "x-token 错误"}
    headers = {"x-token": "test"}
    resp = client.get("/items/foo", headers=headers)
    assert resp.status_code == 400
    assert resp.json() == expect

def test_read_item_error_id():
    expect = {"detail": "找不到 item_id"}
    headers = {"x-token": "coneofsilence"}
    resp = client.get("/items/foos", headers=headers)
    assert resp.status_code == 404
    assert resp.json() == expect

def test_create_item():
    body = {"id": "foos", "title": "Foo", "description": "There goes my hero"}
    headers = {"x-token": "coneofsilence"}
    resp = client.post("/items/", json=body, headers=headers)
    assert resp.status_code == 200
    assert resp.json() == body

def test_create_item_error_header():
    body = {"id": "foo", "title": "Foo", "description": "There goes my hero"}
    expect = {"detail": "x-token 错误"}
    headers = {"x-token": "test"}
    resp = client.post("/items/", json=body, headers=headers)
    assert resp.status_code == 400
    assert resp.json() == expect

def test_create_item_error_id():
    expect = {"detail": "找不到 item_id"}
    body = {"id": "foo", "title": "Foo", "description": "There goes my hero"}
    headers = {"x-token": "coneofsilence"}
    resp = client.post("/items/", json=body, headers=headers)
    assert resp.status_code == 400
    assert resp.json() == expect

命令行运行

pytest test.py -sq

运行结果

> pytest s37_pytest.py -sq
......
6 passed in 0.40s