小型Flask应用的单元测试问题

Question

I have a very primitive Flask application which works as I'm expecting, but I'm failing to write a unit test for it. The code of the app is following (i omit insignificant part):

app.py

from flask import *
import random
import string

app = Flask(__name__)
keys = []
app.testing = True

@app.route('/keygen/api/keys', methods=['POST'])
def create():
    symbol = string.ascii_letters + string.digits
    key = ''.join(random.choice(symbol) for _ in range(4))
    key_instance = {'key': key, 'is_used': False}
    keys.append(key_instance)

    return jsonify({'keys': keys}), 201

The test is:

tests.py

import unittest
from flask import *
import app

class TestCase(unittest.TestCase):
    def test_number_one(self):
        test_app = Flask(app)
        with test_app.test_client() as client:
            rv = client.post('/keygen/api/keys')

        ...something...

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

The traceback:

ERROR: test_number_one (__main__.TestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "tests.py", line 12, in test_number_one
    test_app = Flask(app)
  File "/Users/bulrathi/Yandex.Disk.localized/Virtualenvs/ailove/lib/python3.5/site-packages/flask/app.py", line 346, in __init__
    root_path=root_path)
  File "/Users/bulrathi/Yandex.Disk.localized/Virtualenvs/ailove/lib/python3.5/site-packages/flask/helpers.py", line 807, in __init__
    root_path = get_root_path(self.import_name)
  File "/Users/bulrathi/Yandex.Disk.localized/Virtualenvs/ailove/lib/python3.5/site-packages/flask/helpers.py", line 668, in get_root_path
    filepath = loader.get_filename(import_name)
  File "<frozen importlib._bootstrap_external>", line 384, in _check_name_wrapper
ImportError: loader for app cannot handle <module 'app' from '/Users/bulrathi/Yandex.Disk.localized/Обучение/Code/Django practice/ailove/keygen/app.py'>

----------------------------------------------------------------------
Ran 1 test in 0.003s

FAILED (errors=1)

Thanks for your time.

Answer 1

You have a few issues with the posted code (indentation aside):

First, in tests.py you import app and use it, but app is the module rather than the app object from app.py . You should import the actual app object using

from app import app

and secondly, you are using that app object (assuming we fix the import) as a parameter to another Flask() constructor—essentially saying:

app = Flask(Flask(app))

Since we've imported app from app.py , we can just use it directly, so we remove the app = Flask(app) line (and the associated import statement as we don't need it anymore) and your test file becomes:

import unittest
from app import app

class TestCase(unittest.TestCase):
    def test_number_one(self):
        with app.test_client() as client:
        rv = client.post('/keygen/api/keys')

    ...something...

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

You should note also that the from flask import * form is discouraged in favour of importing specific parts of the module, so

from flask import Flask, jsonify

would be better in your app.py .