使用 pytest 测试 flask api service

背景

使用 pytest 测试 flask api service

框架之选择

为什么选 pytest? 并没有特别原因, 只是刚好看到有个 pytest-flask package, 就先试试了, 用起来还好, 就记录一下.

框架中用到了 fixture, 就是在实际测试的前后加入 setup, teardown 等操作, 是测试必备之选.

测试的几大要素就不多说了.

直接上步骤

安装: pip install pytest-flask

目录结构:

- module1
    - __init__.py
    - src
        - __init__.py
        - app.py
        - config.py
    - test
        - __init__.py
        - conftest.py
        - pytest.ini
        - test_f1.py

创建 flask api service

参考 Application Setup — Flask Documentation (1.1.x)

• 用工厂模式, 在 init.py 中创建 create_app 方法
• 在 app.py 中导入: from src.app import create_app

src/init.py:

import os
from flask import Flask

def create_app(test_config=None):
    # create and configure the app
    app = Flask(__name__, instance_relative_config=False)
    app.config.from_mapping(
        SECRET_KEY='dev',
        DATABASE=os.path.join(app.instance_path, 'flaskr.sqlite'),
    )

    if test_config is None:
        # load the instance config, if it exists, when not testing
        app.config.from_pyfile('config.py', silent=True)
    else:
        # load the test config if passed in
        app.config.from_pyfile(test_config)

    # ensure the instance folder exists
    try:
        os.makedirs(app.instance_path)
    except OSError:
        pass

    # a simple page that says hello
    @app.route('/hello')
    def hello():
        return 'Hello, World!'

    return app

app.py:

from . import create_app
app = create_app()

测试 api service

在 conftest.py 中创建 fixture: @pytest.fixture

import os
import tempfile
import pytest
from src.app import create_app

@pytest.fixture
def client():
    flask_app = create_app() 
    # Flask provides a way to test your application by exposing the Werkzeug test Client
    # and handling the context locals for you.
    client = flask_app.test_client()
    # Establish an application context before running the tests.
    ctx = flask_app.app_context()
    ctx.push()
    yield client  # this is where the testing happens!
    ctx.pop()

在 test_f1.py 中:

import os
def test_f1(client, capsys):
    '''Test f1
    '''
    res = client.get('/hello')
    captured = capsys.readouterr()
    assert 'error' not in captured.err
    assert b'Hello, World!' in res.data

测试范围

有些 test 如果想 ignore 怎么办?

在 conftest.py 中添加:

collect_ignore = [
    "test_f1.py"
    ]

当运行 pytest 的时候, "test_f1.py"就不会在 collected 列表中了.

参考: Changing standard (Python) test discovery — pytest documentation

Tutorials

• Welcome to pytest-flask’s documentation! — pytest-flask 0.10.0 documentation
• Python Web Applications With Flask – Part III – Real Python
• Testing a Flask Application using pytest – Patrick's Software Blog
• Testing Flask Applications — Flask Documentation (1.1.x)
• How to Test a Flask Application
• pytest fixtures: explicit, modular, scalable — pytest documentation

• Quickstart — Flask Documentation (1.1.x)
• the Flask API document for flask.url_for()

ChangLog

• 2020-05-03 init