Pytest: cannot get Flask app to behave in test

Question

I am trying to work out how to use pytest to test the most basic Flask app. (I'm on Windows 10). Here is the app code, myapp.py:

from flask import Flask

api = Flask(__name__)

@api.route('/', methods=['GET'])
def index():
    return 'Index Page'

When I go to http://127.0.0.1:5000/ in a browser, or when I use curl to issue a GET request to that URL it works correctly, I see the 'Index Page' response text.

Then I set up a basic test script, test_app.py:

import pytest
from flask import Flask

def test_assert():
    assert True

def test_home_page(client):
  response = client.get('/')
  assert response.status_code == 200

@pytest.fixture
def client():
  flask_app = Flask(__name__) 
  client = flask_app.test_client()
  return client

I added the first trivial test_assert() function just to ensure pytest was working (I'm v new to python).

Now, when I run pytest (>pytest -v) the first (trivial) test passes, but the test_home_page() test fails. The app returns status code 404 when run through pytest.

collected 2 items

test_app.py::test_assert PASSED                                                                                  [ 50%]
test_app.py::test_home_page FAILED                                                                               [100%]

====================================================== FAILURES =======================================================
___________________________________________________ test_home_page ____________________________________________________

client = <FlaskClient <Flask 'test_app'>>

    def test_home_page(client):
      response = client.get('/')
>     assert response.status_code == 200
E     assert 404 == 200
E       -404
E       +200

test_app.py:10: AssertionError
========================================= 1 failed, 1 passed in 0.28 seconds ====

I've spent a couple of days reading around trying to determine why pytest fails for this simple example -- the response should be 200, but it keeps giving 404.

Can anyone see what I've done wrong or why this won't work? Thanks.

Answer 1

try this:

from YOUR_MODULE import api 

def test_assert():
    assert True

def test_home_page(client):
  response = client.get('/')
  assert response.status_code == 200

@pytest.fixture
def client():
  client = api.test_client()
  return client