Change a way fixtures are called in pytest

Question

I am having a fixture in conftest.py

@pytest.fixture(scope="function", autouse=True)
@pytest.mark.usefixtures
def pause_on_assert():
    yield
    if hasattr(sys, 'last_value') and isinstance(sys.last_value, AssertionError):
        tkinter.messagebox.showinfo(sys.last_value)

Similarly there are many other fixures in the conftest.py with scope as session, module

My test cases looks like this

test.py

@pytest.fixture(scope="function", autouse=True)
def _wrapper:
    print("pre condition")
    yield
    print("post condition")

def test_abc():
    assert 1==0

Problem is I want my fixture that is there in conftest.py to run before yield of fixture that is in my testcase

How can i change order in the way fixture are executed

Answer 1

Here is an example of running my conftest.py function that prints "A" before my test function that prints "B".

cd to the parent directory, for this example it is py_tests and run.

pytest -s -v

The output is:

A
setting up
B
PASSED

---

With directory structure:

py_tests
 -conftest.py
 -tests
  --tests.py

---

Files:

conftest.py

---

import pytest

@pytest.fixture(scope="function")
def print_one():
    print("\n")
    print("A")

---

test.py

---

import pytest

class Testonething:

    @pytest.fixture(scope="function", autouse=True)
    def setup(self, print_one):
        print("setting up")

    def test_one_thing(self):
        print("B")
        assert True

Answer 2

If you want to ensure a piece of code runs after the test function, but before all fixtures teardown, I'd advise to use the pytest_runtest_teardown hook instead. Replace the pause_on_assert fixture in your conftest.py with:

def pytest_runtest_teardown(item, nextitem):
    if hasattr(sys, 'last_value') and isinstance(sys.last_value, AssertionError):
        tkinter.messagebox.showinfo(sys.last_value)

Answer 3

Since your _wrapper is a function-scoped autouse fixture: it will be instantiated before other fixtures within the same scope. So, hot fix is to define _wrapper without autouse=True and try to call that decorator implicitly like:

def test_abc(_wrapper):
    assert 1==0

Autouse source

[Update] If you don't have an ability to change your test suites, I suggest you just wipe all local specific _wrapper and refactor your conftest-specified fixture to call _wrapper, because fixture functions can use other fixtures themselves. Your conftest.py will be look like this:

# conftest.py
@pytest.fixture(scope="function", autouse=True)
def _wrapper(pause_on_assert):
    print("pre condition")
    yield
    print("post condition")

@pytest.fixture()
def pause_on_assert():
    yield
    if hasattr(sys, 'last_value') and isinstance(sys.last_value, AssertionError):
        tkinter.messagebox.showinfo(sys.last_value)

Modularity source