python - How to apply integration tests to a Flask RESTful API

Question

[As per https://stackoverflow.com/a/46369945/1021819, the title should refer to integration tests rather than unit tests]

Suppose I'd like to test the following Flask API (from here):

import flask
import flask_restful

app = flask.Flask(__name__)
api = flask_restful.Api(app)

class HelloWorld(flask_restful.Resource):
    def get(self):
        return {'hello': 'world'}

api.add_resource(HelloWorld, '/')

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

Having saved this as flaskapi.py and run it, in the same directory I run the script test_flaskapi.py:

import unittest
import flaskapi
import requests

class TestFlaskApiUsingRequests(unittest.TestCase):
    def test_hello_world(self):
        response = requests.get('http://localhost:5000')
        self.assertEqual(response.json(), {'hello': 'world'})


class TestFlaskApi(unittest.TestCase):
    def setUp(self):
        self.app = flaskapi.app.test_client()

    def test_hello_world(self):
        response = self.app.get('/')

if __name__ == "__main__":
    unittest.main()

Both the tests pass, but for the second test (defined in the TestFlaskApi) class I haven't yet figured out how to assert that the JSON response is as expected (namely, {'hello': 'world'}). This is because it is an instance of flask.wrappers.Response (which is probably essentially a Werkzeug Response object (cf. http://werkzeug.pocoo.org/docs/0.11/wrappers/)), and I haven't been able to find an equivalent of the json() method for requests Response object.

How can I make assertions on the JSON content of the second response?

Answer 1

Flask provides a test_client you can use in your tests:

from source.api import app
from unittest import TestCase

class TestIntegrations(TestCase):
    def setUp(self):
        self.app = app.test_client()

    def test_thing(self):
        response = self.app.get('/')
        assert <make your assertion here>

Flask Testing Docs