用Python写一个上传接口，并给出测试用例

好的，下面是一个使用Python编写的简单的文件上传接口的示例代码，以及测试用例：

from flask import Flask, request

app = Flask(__name__)

@app.route('/upload', methods=['POST'])
def upload_file():
    file = request.files['file']
    if file:
        filename = file.filename
        file.save(filename)
        return 'File uploaded successfully'
    else:
        return 'No file was uploaded'

if __name__ == '__main__':
    app.run(debug=True)

这个接口会监听POST请求，并尝试从请求中获取一个名为“file”的文件对象。如果成功获取到了文件对象，就将其保存在当前工作目录下，文件名与上传时的文件名相同，并返回“File uploaded successfully”；如果没有获取到文件对象，则返回“No file was uploaded”。

接下来是测试用例：

import requests

def test_upload_file():
    url = 'http://localhost:5000/upload'
    files = {'file': ('test.txt', b'This is a test file.')}
    response = requests.post(url, files=files)
    assert response.status_code == 200
    assert response.text == 'File uploaded successfully'

    files = {'file': ('', b'This is another test file.')}
    response = requests.post(url, files=files)
    assert response.status_code == 200
    assert response.text == 'No file was uploaded'

这个测试用例会首先向接口上传一个名为“test.txt”的文件，文件内容为“This is a test file.”。然后它会检查接口的响应状态码是否为200，并检查响应内容是否为“File uploaded successfully”。接着，它会再次向接口上传一个空文件，然后检查接口的响应状态码是否为200，并检查响应内容是否为“No file was uploaded”。如果所有的断言都通过了，那么就说明接口工作正常。