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Can I programmatically parametrize return value of a pytest fixture?

I am working on some functional tests for my application. Depending on the logged user's permissions, the sidebar will have different links. I am parameterizing them (hard coded) and running a test that works well (app is a webtest app):
endpoints = [
'/',
'/endpoint1',
'endpoint2',
...
]
#pytest.mark.parametrize('endpoint', endpoints)
def test_endpoints(endpoint, app):
res = app.get(endpoint).maybe_follow()
assert res.status_code == 200
I would like to avoid having to hard code the list of links for each type of user. Inside a fixture I can actually get them programmatically, so ideally I would like to parametrize the return value of this fixture in order to run the test function above:
#pytest.fixture
def endpoints(app):
res = app.get('/login').follow()
sidebar_links = []
for link in res.html.ul.find_all('a'):
if link.has_attr('href') and not link['href'].startswith('#'):
sidebar_links.append(link['href'])
return sidebar_links
Is this possible?

I would suggest that you use the pytest_configure() hook instead as this method will run before all your test methods. in conftest.py file you can keep a global variable as pytest.endpoints= [] then later in the hook method keep on appending the value of endpoints to this variable
something like this
pytest.endpoints= []
def pytest_configure(config,app):
res = app.get('/login').follow()
for link in res.html.ul.find_all('a'):
if link.has_attr('href') and not link['href'].startswith('#'):
pytest.endpoints.append(link['href'])
within the test method use the same variable as a parameter like below
#pytest.mark.parametrize("endpoint",pytest.endpoints)
def test_endpoints(endpoint):
Well i am not completely aware of your design so i cannot suggest any further but you can give this a try.

Patching imported functions in a Pytest fixture

I am having issues properly patching an imported function in pytest. The function I want to patch is a function designed to do a large SQL fetch, so for speed I would like to replace this with reading a CSV file. Here is the code I currently have:
from data import postgres_fetch
import pytest
#pytest.fixture
def data_patch_market(monkeypatch):
test_data_path = os.path.join(os.path.dirname(__file__), 'test_data')
if os.path.exists(test_data_path):
mock_data_path = os.path.join(test_data_path, 'test_data_market.csv')
mock_data = pd.read_csv(mock_data_path)
monkeypatch.setattr(postgres_fetch, 'get_data_for_market', mock_data)
def test_mase(data_patch_market):
data = postgres_fetch.get_data_for_market(market_name=market,
market_level=market_level,
backtest_log_ids=log_ids,
connection=conn)
test_result= build_features.MASE(data)
However when I run this test I am getting a type error about calling a DataFrame:
TypeError: 'DataFrame' object is not callable
I know the csv can be read properly as I've tested that separately, so I assume something is wrong with how I am implementing the patch fixture, but I can't seem to work it out

Here, your call to monkeypatch.setattr is replacing any call to postgres_fetch.get_data_for_market with a call to mock_data.
This can't work since mock_data is not a function - its a DataFrame object.
Instead, in your call to monkeypatch.setattr, you need to pass in a function that returns the mocked data (i.e. the DataFrame object).
Hence, something like this should work:
#pytest.fixture
def data_patch_market(monkeypatch):
test_data_path = os.path.join(os.path.dirname(__file__), 'test_data')
if os.path.exists(test_data_path):
mock_data_path = os.path.join(test_data_path, 'test_data_market.csv')
mock_data = pd.read_csv(mock_data_path)
# The lines below are new - here, we define a function that will return the data we have mocked
def return_mocked(*args, **kwargs):
return mock_data
monkeypatch.setattr(postgres_fetch, 'get_data_for_market', return_mocked)

AttributeError when using request.function in pytest yield fixture

I have several pytest test cases that need nearly identical setup, so I would like to have them reuse a fixture to keep things DRY. The setup involves creating a new ticket in an external ticket tracking system, then the test cases interact with the ticket based on the data, and finally the fixture cleans up by closing out the ticket. The challenge here is that each test case needs slightly different data to be prepped in the ticket.
Each test case has different calls and different assertions, so I can't combine them all into a single parametrized test case with a single test fixture. Parametrizing the the fixture itself would result in every test case running every permutation of the fixture data, which ends up with a lot of irrelevant test failures.
What I would like to do is set a variable in the test case, then have the fixture use that variable to set up the test data when creating the ticket. I've tried to use request.function as specified in the pytest fixture docs but I keep getting:
=================================== ERRORS ===================================
____________________ ERROR at setup of TestMCVE.test_stuff ___________________
request = <SubRequest 'ticket' for <Function 'test_stuff'>>
#pytest.yield_fixture
def ticket(request):
> ticket_summary = getattr(request.function, "summary")
E AttributeError: 'function' object has no attribute 'summary'
tests\test_mcve.py:11: AttributeError
My code is:
import pytest
def ticket_system_api(summary):
# stub for MCVE purposes
return summary
#pytest.yield_fixture
def ticket(request):
ticket_summary = getattr(request.function, "summary")
new_ticket = ticket_system_api(summary=ticket_summary)
yield new_ticket
class TestMCVE:
def test_stuff(self, ticket):
summary = 'xyz'
# do real things here, except MCVE
assert 'xyz' == ticket
I've tried using request.node instead of request.function as well as binding the summary variable per this answer, changing summary = 'xyz' to test_stuff.summary = 'xyz' but these still fail with the same AttributeError.
How can I pass the function level data to the fixture?

You can accomplish this with indirect parametrization. The API (and the documentation) could be friendlier, but the functionality you want is there.
Your example was very close, and minor tweaks were needed. Take a look:
import pytest
def ticket_system_api(summary):
# stub for MCVE purposes
return summary
#pytest.fixture
def ticket(request):
# NOTE: This will raise `AttributeError` if the fixture
# doesn't receive a parameter.
ticket_summary = request.param
new_ticket = ticket_system_api(summary=ticket_summary)
return new_ticket
class TestMCVE:
#pytest.mark.parametrize('ticket', ('abc',), indirect=True)
def test_abc(self, ticket):
# do real things here, except MCVE
assert ticket == 'abc'
#pytest.mark.parametrize('ticket', ('xyz',), indirect=True)
def test_xyz(self, ticket):
# do real things here, except MCVE
assert ticket == 'xyz'

Mock flask.request in python nosetests

I'm writing test cases for code that is called via a route under Flask. I don't want to test the code by setting up a test app and calling a URL that hits the route, I want to call the function directly. To make this work I need to mock flask.request and I can't seem to manage it. Google / stackoverflow searches lead to a lot of answers that show how to set up a test application which again is not what I want to do.
The code would look something like this.
somefile.py
-----------
from flask import request
def method_called_from_route():
data = request.values
# do something with data here
test_somefile.py
----------------
import unittest
import somefile
class SomefileTestCase(unittest.TestCase):
#patch('somefile.request')
def test_method_called_from_route(self, mock_request):
# want to mock the request.values here
I'm having two issues.
(1) Patching the request as I've sketched out above does not work. I get an error similar to "AttributeError: 'Blueprint' object has no attribute 'somefile'"
(2) I don't know how to exactly mock the request object if I could patch it. It doesn't really have a return_value since it isn't a function.
Again I can't find any examples on how to do this so I felt a new question was acceptable.

Try this
test_somefile.py
import unittest
import somefile
import mock
class SomefileTestCase(unittest.TestCase):
def test_method_called_from_route(self):
m = mock.MagicMock()
m.values = "MyData"
with mock.patch("somefile.request", m):
somefile.method_called_from_route()
unittest.main()
somefile.py
from flask import request
def method_called_from_route():
data = request.values
assert(data == "MyData")
This is going to mock the entire request object.
If you want to mock only request.values while keeping all others intact, this would not work.

A few years after the question was asked, but this is how I solved this with python 3.9 (other proposed solutions stopped working with python 3.8 see here). I'm using pytest and pytest-mock, but the idea should be the same across testing frameworks, as long as you are using the native unittest.mock.patch in some capacity (pytest-mock essentially just wraps these methods in an easier to use api). Unfortunately, it does require that you set up a test app, however, you do not need to go through the process of using test_client, and can just invoke the function directly.
This can be easily handled by using the Application Factory Design Pattern, and injecting application config. Then, just use the created app's .test_request_context as a context manager to mock out the request object. using .test_request_context as a context manager, gives everything called within the context access to the request object. Here's an example below.
import pytest
from app import create_app
#pytest.fixture
def request_context():
"""create the app and return the request context as a fixture
so that this process does not need to be repeated in each test
"""
app = create_app('module.with.TestingConfig')
return app.test_request_context
def test_something_that_requires_global_request_object(mocker, request_context):
"""do the test thing"""
with request_context():
# mocker.patch is just pytest-mock's way of using unittest.mock.patch
mock_request = mocker.patch('path.to.where.request.is.used')
# make your mocks and stubs
mock_request.headers = {'content-type': 'application/json'}
mock_request.get_json.return_value = {'some': 'json'}
# now you can do whatever you need, using mock_request, and you do not
# need to remain within the request_context context manager
run_the_function()
mock_request.get_json.assert_called_once()
assert 1 == 1
# etc.
pytest is great because it allows you to easily setup fixtures for your tests as described above, but you could do essentially the same thing with UnitTest's setUp instance methods. Happy to provide an example for the Application Factory design pattern, or more context, if necessary!

with help of Gabrielbertouinataa on this article: https://medium.com/#vladbezden/how-to-mock-flask-request-object-in-python-fdbc249de504:
code:
def print_request_data():
print(flask.request.data)
test:
flask_app = flask.Flask('test_flask_app')
with flask_app.test_request_context() as mock_context:
mock_context.request.data = "request_data"
mock_context.request.path = "request_path"
print_request_data()

Here is an example of how I dealt with it:
test_common.py module
import pytest
import flask
def test_user_name(mocker):
# GIVEN: user is provided in the request.headers
given_user_name = "Some_User"
request_mock = mocker.patch.object(flask, "request")
request_mock.headers.get.return_value = given_user_name
# WHEN: request.header.get method is called
result = common.user_name()
# THEN: user name should be returned
request_mock.headers.get.assert_called_once_with("USERNAME", "Invalid User")
assert result == given_user_name
common.py module
import flask
def user_name():
return flask.request.headers.get("USERNAME", "Invalid User")

What you're trying to do is counterproductive. Following the RFC 2616 a request is:
A request message from a client to a server includes, within the first line of that message, the method to be applied to the resource, the identifier of the resource, and the protocol version in use.
Mocking the Flask request you need to rebuild its structure, what certainly, you will not to want to do!
The best approach should be use something like Flask-Testing or use some recipes like this, and then, test your method.

pytest fixture to introspect calling function

I have a test class and a setup function that looks like this:
#pytest.fixture(autouse=True, scope='function')
def setup(self, request):
self.client = MyClass()
first_patcher = patch('myclass.myclass.function_to_patch')
first_mock = first_patcher.start()
first_mock.return_value = 'foo'
value_to_return = getattr(request, 'value_name', None)
second_patcher = patch('myclass.myclass.function_two')
second_mock = second_patcher.start()
second_mock.return_value = value_to_return
#could clean up my mocks here, but don't care right now
I see in the documentation for pytest, that introspection can be done for a module level value:
val = getattr(request.module, 'val_name', None)
But, I want to be able to specify different values to return based on the test I am in. So I am looking for a way to introspect the test_function not the test_module.
http://pytest.org/latest/fixture.html#fixtures-can-introspect-the-requesting-test-context

You can use request.function to get to the test function. Just follow the link on the b wepage you referenced to see what is available on the test request object :)

Maybe the documentation has changed since the time of the accepted answer.
At least for me it was not clear how to
Just follow the link
So I thought I'd update this thread with the link itself:
https://pytest.org/en/6.2.x/reference.html#request
Edit December 2021
Even when the link is correct now I think this statement from the pytest documentation is just not correct:
Fixture functions can accept the request object to introspect the “requesting” test function ...
While I found some examples for getting attributes of the module I did not find a single working example of introspecting the test function that requests the fixture. May be related to collection and runtime order.
What really helped me to get the desired behavior was to use the factory idiom a little further down in the pytest documentation:
https://pytest.org/en/6.2.x/fixture.html#factories-as-fixtures
Set up the fixture factory
#pytest.fixture(scope='function')
def getQueryResult() -> object:
def _impl(_mrId: int = 7622):
return QueryResult(_mrId)
return _impl
Usage
# Concrete value
def test_foo(getQueryResult):
queryResult = getQueryResult(4711)
...
# Default value
def test_bar(getQueryResult):
queryResult = getQueryResult()
...