404 Not Found when testing Flask application with pytest - unit-testing

Question

This simple web service works if I run it by hand but in my unit tests I get a 404 not found page as my response, preventing me to properly test the application.
normal behavior:
Folder structure:
/SRC
--web_application.py
/UNIT_TESTS
--test_wab_application.py
web_application.py
from flask import Flask, request, jsonify, send_from_directory
from python.Greeting import Greeting
application = Flask(__name__)
def create_app(test_config=None):
# create and configure the app
app = Flask(__name__, instance_relative_config=True)
app.config.from_mapping(
SECRET_KEY='mega_developer',
DATABASE=os.path.join(app.instance_path, 'web_application.sqlite'),
)
try:
os.makedirs(app.instance_path)
except OSError:
pass
return app
#application.route('/greetings', methods=['GET', 'POST'])
def hello():
# GET: for url manipulation #
if request.method == 'GET':
return jsonify(hello = request.args.get('name', 'world', str))
test_web_application.py
import tempfile
import pytest
import web_application
class TestWebApplication:
app = web_application.create_app() # container object for test applications #
#pytest.fixture
def initialize_app(self):
app = web_application.create_app()
app.config['TESTING'] = True
app.config['DEBUG'] = False
app.config['WTF_CSRF_ENABLED'] = False
app.config['DATABASE'] = tempfile.mkstemp()
app.testing = True
self.app = app
def test_hello_get(self, initialize_app):
with self.app.test_client() as client:
response = client.get('/greetings?name=Rick Sanchez')
assert response.status_code == 200
test results (most relevant part only):
Launching pytest with arguments test_web_application.py::TestWebApplication::test_hello_get in C:\Users\Xrenyn\Documents\Projekte\Studium_Anhalt\QA&Chatbots Exercises\Exercise 2 - Web Service Basics\UNIT_TESTS
============================= test session starts =============================
platform win32 -- Python 3.8.0, pytest-5.2.2, py-1.8.0, pluggy-0.13.0 -- C:\Users\Xrenyn\Documents\Projekte\Studium_Anhalt\QA&Chatbots Exercises\Exercise 2 - Web Service Basics\VENV\Scripts\python.exe
cachedir: .pytest_cache
rootdir: C:\Users\Xrenyn\Documents\Projekte\Studium_Anhalt\QA&Chatbots Exercises\Exercise 2 - Web Service Basics\UNIT_TESTS
collecting ... collected 1 item
test_web_application.py::TestWebApplication::test_hello_get FAILED [100%]
test_web_application.py:21 (TestWebApplication.test_hello_get)
404 != 200
Expected :200
Actual :404
So far I have tested various alternative routing paths for the client.get() method in test-web_application.py , including combinations like '/SRC/greetings?name=Rick Sanchez' or '../SRC/greetings?name=Rick Sanchez', but all to no different effect.
Do you have any idea on what I might be doing wrong or how I could get access to my web services' functions from within unit tests?

Answer 1

I think the problem is that you are creating two Flask instances. One with the name application that you add hello route to, and the second one using the create_app function. You need to create a test client using the application instance (the one you added the hello route to).
Can you import application and then obtain the client using application.test_client()?
Sample solution:
import pytest
from web_application import application
#pytest.fixture
def client():
with application.test_client() as client:
yield client
class TestSomething:
def test_this(self, client):
res = client.get('/greetings?name=Rick Sanchez')
assert res.status_code == 200
Checkout the official docs on testing.