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ScopeMismatch when i try to make setup_teardown pytest function

My goal is to create a fixture that will run once at the beginning of the class function test and initialize the attributes I need in self. To do this, I created a fixture with the scope of the class and applied it directly to the class. To solve the compatibility problem of pytest with asynchronous code, pytest-asyncio was used.
My minimally reproducible example:
import pytest
#pytest.fixture(scope="class")
async def setup_teardown(request):
request.cls.test_number = '123'
yield
# ...
#pytest.mark.asyncio
#pytest.mark.usefixtures("setup_teardown")
class Test_BaseFunctional():
async def test_my_number(self):
assert self.test_number == '123'
But i'm receiving:
ScopeMismatch: You tried to access the function scoped fixture event_loop with a class scoped request object, involved factories:
tests/issue.py:4: def setup_teardown(request)
I tried many ways, from time to time I got a large-scale non-working code, and in the end I returned to this minimal example in the hope of help from you, dear friends.

The reason was in pytest-asyncio fixtures realization. They has scope "function" which not implicated with higher-level fixtures, such as the scope "class". In this case, we just need to redefine event_loop fixture to eliminate ScopeMismatch.
#pytest.fixture(scope="class")
def event_loop():
policy = asyncio.get_event_loop_policy()
loop = policy.new_event_loop()
yield loop
loop.close()
You can put this code into coftest.py file.

Run setup_class() class after class scope fixture defined in conftest

So, I have fixtures defined in conftest.py file with scope="class" as I want to run them before each test class is invoked. The conftest file is placed inside project root directory for it to be visible to every test module.
Now in one of the test modules, I have another setup function which I want to run once for that module only. But the problem is setup_class() method is called before running fixtures defined in conftest.py. Is this expected? I wanted it to be opposite because I want to use something done in the fixtures defined in conftest. How to do that?
Code -
conftest.py:
#pytest.fixture(scope="class")
def fixture1(request):
#set a
#pytest.fixture(scope="class")
def fixture1(request):
test_1.py:
#pytest.mark.usefixtures("fixture_1", "fixture_2")
class Test1():
#need this to run AFTER the fixture_1 & fixture_2
def setup_class():
#setup
#get a set in fixture_1
def test_1()
.....
I know that I could simply define a fixture in the test file instead of setup_class but then I will have to specify it in arguments of every test method in order it to be invoked by pytest. But suggestions are welcome!

I have exactly the same problem. Only now I have realized that the problem might be taht the setup_class is called before the fixture >-/
I think that this question is similar to this one
Pytest - How to pass an argument to setup_class?
And the problem is mixing the unittest and pytest methods.
I kind of did what they suggested - I ommitted the setup_class and created a new fixture within the particular test file,
calling the fixture in the conftest.py.
It works so far.
M.

The problem is that you can use the result of a fixture only in test function (or method) which is run by pytest. Here I can suggest a workaround. But of course I'm not sure if it suites your needs.
The workaround is to call the function from a test method:
conftest.py
#pytest.fixture(scope='class')
def fixture1():
yield 'MYTEXT'
test_1.py
class Test1:
def setup_class(self, some_var):
print(some_var)
def test_one(self, fixture1):
self.setup_class(fixture1)

Fixtures and setup_class are two different paradigms to initialize test functions (and classes). In this case, mixing the two creates a problem: The class-scoped fixtures run when the individual test functions (methods) run. On the other hand, setup_class runs before they do. Hence, it is not possible to access a fixture value (or fixture-modified state) from setup_class.
One of the solutions is to stop using setup_class entirely and stick with a fixtures-only solution which is the preferred way in pytest nowadays (see the note at the beginning).
# conftest.py or the test file:
#pytest.fixture(scope="class")
def fixture_1(request):
print('fixture_1')
# the test file:
class Test1():
#pytest.fixture(scope="class", autouse=True)
def setup(self, fixture_1, request):
print('Test1.setup')
def test_a(self):
print('Test1.test_a')
def test_b(self):
print('Test1.test_b')
Note that the setup fixture depends on fixture_1 and hence can access it.

Which target is needed to mock modules used inside a Class with unittest.mock?

I need to create a module-scoped fixture where I mock module_a and module_c used inside module_b.Module_B_Class(). I cannot use mock.patch annotation because it provides a function-scoped mock and I also need to assert that, when invoking Module_B_Class a specific function is invoked on module_a and another function is invoked on module_c. So I used pytest-cases unpack_into feature and wrote the following fixture:
#pytest_cases.fixture_plus(scope="module", unpack_into="mocked_module_a,mocked_module_b")
def my_fixture():
with mock.patch('my_top_module.my_sub_module.module_b.module_a') as module_a_mock:
with mock.patch('my_top_module.my_sub_module.module_b.module_c') as module_c_mock:
module_a_mock.my_func = MagicMock(return_value='Hello world')
module_c_mock.my_func_2 = MagicMock(return_value='Good morning')
However, when I run the following:
def test_my_class(mocked_module_a, mocked_module_b):
my_class = Module_B_Class()
my_class.run()
mocked_module_a.assert_called_once()
mocked_module_b.assert_called_once()
which is defined like so
from my_top_module.my_sub_module import module_a
class Module_B_Class():
def run(self):
module_a.my_func()
module_c.my_func2()
the function which is invoked is the original one and not the replaced one. Is the target I am patching the wrong one?

Fixtures are described in the pytest documentation. The basic principle is that the code before the yield is executed before the test (or depending on the scope, before the first test, each module, or each test class), and the code after the yield is executed after the test (or the last test, the module, or class):
#pytest.fixture
def my_fixture():
do_setup()
yield
do_teardown()
You can also return a value using yield, of course.
For a context manager that means, you have to yield before going out of scope:
#pytest.fixture(scope="module")
def my_fixture():
with mock.patch('my_top_module.my_sub_module.module_b.module_a') as module_a_mock:
module_a_mock.my_func = MagicMock(return_value='Hello world')
yield module_a_mock
You can now access the mock via the fixture name in your test, if you need to. In this case, the code returns after the yield only after the tests in the current module are executed, so at that point the patch is reverted.
If you don't do the yield in this case, you get out of scope immediately on fixture execution, meaning that the patch is reverted before you get to the test.
UPDATE:
Here is the version for the updated question which uses pytest_cases:
#pytest_cases.fixture_plus(scope="module",
unpack_into="mocked_module_a,mocked_module_c")
def my_fixture():
with mock.patch(
'my_top_module.my_sub_module.module_b.module_a') as module_a_mock:
with mock.patch(
'my_top_module.my_sub_module.module_b.module_c') as module_c_mock:
module_a_mock.my_func = mock.MagicMock(return_value='Hello world')
module_c_mock.my_func2 = mock.MagicMock(return_value='Good morning')
yield (module_a_mock, module_c_mock)
def test_my_class(mocked_module_a, mocked_module_c):
my_class = Module_B_Class()
my_class.run()
mocked_module_a.my_func.assert_called_once()
mocked_module_c.my_func2.assert_called_once()
Note: I have renamed mocked_module_b to mocked_module_c to avoid confusion. Also assert_called_once had been called on the module instead of the function.

Pytest fixture with scope "class" running on every method

I'm trying to create a test environment with Pytest. The idea is to group test methods into classes.
For every class/group, I want to attach a config fixture that is going to be parametrized. So that I can run all the tests with "configuration A" and then all tests with "configuration B" and so on.
But also, I want a reset fixture, that can be executed before specific methods or all methods of a class.
The problem I have there is, once I apply my reset fixture (to a method or to a whole class), the config fixture seems to work in the function scope instead of the class scope. So, once I apply the reset fixture, the config fixture is called before/after every method in the class.
The following piece of code reproduces the problem:
import pytest
from pytest import *
#fixture(scope='class')
def config(request):
print("\nconfiguring with %s" % request.param)
yield
print("\ncleaning up config")
#fixture(scope='function')
def reset():
print("\nreseting")
#mark.parametrize("config", ["config-A", "config-B"], indirect=True)
##mark.usefixtures("reset")
class TestMoreStuff(object):
def test_a(self, config):
pass
def test_b(self, config):
pass
def test_c(self, config):
pass
The test shows how the config fixture should work, being executed only once for the whole class. If you uncomment the usefixtures decoration, you can notice that the config fixture will be executed in every test method. Is it possible to use the reset fixture without triggering this behaviour?

As I mentioned in a comment, that seems to be a bug in Pytest 3.2.5.
There's a workaround, which is to "force" the scope of a parametrization. So, in this case if you include the scope="class" in the parametrize decorator, you get the desired behaviour.
import pytest
from pytest import *
#fixture(scope='class')
def config(request):
print("\nconfiguring with %s" % request.param)
yield
print("\ncleaning up config")
#fixture(scope='function')
def reset():
print("\nreseting")
#mark.parametrize("config", ["config-A", "config-B"], indirect=True, scope="class")
#mark.usefixtures("reset")
class TestMoreStuff(object):
def test_a(self, config):
pass
def test_b(self, config):
pass
def test_c(self, config):
pass

It depends on which version of pytest you are using.
There are some semantical problems to implement this in older versions of pytest. So, this idea is not yet implemented in older pytest. Someone has already given suggestion to implement the same. you can refer this
"Fixture scope doesn't work when parametrized tests use parametrized fixtures".
This was the bug.
You can refer this
This issue has been resolved in latest version of pytest. Here's the commit for the same with pytest 3.2.5
Hope it would help you.

Run code before and after each test in py.test?

I want to run additional setup and teardown checks before and after each test in my test suite. I've looked at fixtures but not sure on whether they are the correct approach. I need to run the setup code prior to each test and I need to run the teardown checks after each test.
My use-case is checking for code that doesn't cleanup correctly: it leaves temporary files. In my setup, I will check the files and in the teardown I also check the files. If there are extra files I want the test to fail.

py.test fixtures are a technically adequate method to achieve your purpose.
You just need to define a fixture like that:
#pytest.fixture(autouse=True)
def run_around_tests():
# Code that will run before your test, for example:
files_before = # ... do something to check the existing files
# A test function will be run at this point
yield
# Code that will run after your test, for example:
files_after = # ... do something to check the existing files
assert files_before == files_after
By declaring your fixture with autouse=True, it will be automatically invoked for each test function defined in the same module.
That said, there is one caveat. Asserting at setup/teardown is a controversial practice. I'm under the impression that the py.test main authors do not like it (I do not like it either, so that may colour my own perception), so you might run into some problems or rough edges as you go forward.

You can use a fixture in order to achieve what you want.
import pytest
#pytest.fixture(autouse=True)
def run_before_and_after_tests(tmpdir):
"""Fixture to execute asserts before and after a test is run"""
# Setup: fill with any logic you want
yield # this is where the testing happens
# Teardown : fill with any logic you want
Detailed Explanation
#pytest.fixture(autouse=True), from the docs: "Occasionally, you may want to have fixtures get invoked automatically without declaring a function argument explicitly or a usefixtures decorator." Therefore, this fixture will run every time a test is executed.
# Setup: fill with any logic you want, this logic will be executed before every test is actually run. In your case, you can add your assert statements that will be executed before the actual test.
yield, as indicated in the comment, this is where testing happens
# Teardown : fill with any logic you want, this logic will be executed after every test. This logic is guaranteed to run regardless of what happens during the
tests.
Note: in pytest there is a difference between a failing test and an error while executing a test. A Failure indicates that the test failed in some way.
An Error indicates that you couldn't get to the point of doing a proper test.
Consider the following examples:
Assert fails before test is run -> ERROR
import pytest
#pytest.fixture(autouse=True)
def run_around_tests():
assert False # This will generate an error when running tests
yield
assert True
def test():
assert True
Assert fails after test is run -> ERROR
import pytest
#pytest.fixture(autouse=True)
def run_around_tests():
assert True
yield
assert False
def test():
assert True
Test fails -> FAILED
import pytest
#pytest.fixture(autouse=True)
def run_around_tests():
assert True
yield
assert True
def test():
assert False
Test passes -> PASSED
import pytest
#pytest.fixture(autouse=True)
def run_around_tests():
assert True
yield
assert True
def test():
assert True

Fixtures are exactly what you want.
That's what they are designed for.
Whether you use pytest style fixtures, or setup and teardown (module, class, or method level) xUnit style fixtures, depends on the circumstance and personal taste.
From what you are describing, it seems like you could use pytest autouse fixtures.
Or xUnit style function level setup_function()/teardown_function().
Pytest has you completely covered. So much so that perhaps it's a fire hose of information.

You can use Module level setup/teardown Fixtures of Pytest.
Here's the Link
http://pytest.org/latest/xunit_setup.html
It Works as follows:
def setup_module(module):
""" setup any state specific to the execution of the given module."""
def teardown_module(module):
""" teardown any state that was previously setup with a setup_module
method."""
Test_Class():
def test_01():
#test 1 Code
It will call setup_module before this test and teardown_module after test completes.
You can include this fixture in each test-script to run it for each test.
IF you want to use something that is common to all tests in a directory You can use package/directory level fixtures nose framework
http://pythontesting.net/framework/nose/nose-fixture-reference/#package
In __init__.py file of the package you can include following
def setup_package():
'''Set up your environment for test package'''
def teardown_package():
'''revert the state '''

You may use decorators but programatically, so you don't need to put the decorator in each method.
I'm assuming several things in next code:
The test methods are all named like: "testXXX()"
The decorator is added to the same module where test methods are implemented.
def test1():
print ("Testing hello world")
def test2():
print ("Testing hello world 2")
#This is the decorator
class TestChecker(object):
def __init__(self, testfn, *args, **kwargs):
self.testfn = testfn
def pretest(self):
print ('precheck %s' % str(self.testfn))
def posttest(self):
print ('postcheck %s' % str(self.testfn))
def __call__(self):
self.pretest()
self.testfn()
self.posttest()
for fn in dir() :
if fn.startswith('test'):
locals()[fn] = TestChecker(locals()[fn])
Now if you call the test methods...
test1()
test2()
The output should be something like:
precheck <function test1 at 0x10078cc20>
Testing hello world
postcheck <function test1 at 0x10078cc20>
precheck <function test2 at 0x10078ccb0>
Testing hello world 2
postcheck <function test2 at 0x10078ccb0>
If you have test methods as class methods, the approach is also valid. For instance:
class TestClass(object):
#classmethod
def my_test(cls):
print ("Testing from class method")
for fn in dir(TestClass) :
if not fn.startswith('__'):
setattr(TestClass, fn, TestChecker(getattr(TestClass, fn)))
The call to TestClass.my_test() will print:
precheck <bound method type.my_test of <class '__main__.TestClass'>>
Testing from class method
postcheck <bound method type.my_test of <class '__main__.TestClass'>>

It is an old question but I personally found another way from the docs :
Use the pytest.ini file :
[pytest]
usefixtures = my_setup_and_tear_down
import pytest
#pytest.fixture
def my_setup_and_tear_down():
# SETUP
# Write here the logic that you need for the setUp
yield # this statement will let the tests execute
# TEARDOWN
# Write here the logic that you need after each tests
About the yield statement and how it allows to run the test : HERE

Fixtures by default have scope=function. So, if you just use a definition such as
#pytest.fixture
def fixture_func(self)
It defaults to (scope='function').
So any finalizers in the fixture function will be called after each test.