Fixture scope is non-deterministic

[pytestbot]

Originally reported by: Nikolaus Rath (BitBucket: nikratio, GitHub: nikratio)

---

Consider the attached test case. Both fixtures are defined with module scope, so they should be called just once for each parameter value.

However, sometimes the "bar" fixture is called twice for the same parameter value. Example:

#!

$ py.test-3 test_bug.py -s
============================= test session starts =============================
platform linux -- Python 3.4.2 -- py-1.4.25 -- pytest-2.6.3
plugins: capturelog, ordering
collected 4 items 

test_bug.py preparing bar-1
preparing bar-1/foo-1
.preparing bar-2
preparing bar-2/foo-1
.preparing bar-2/foo-2
.preparing bar-1
preparing bar-1/foo-2
.

========================== 4 passed in 0.01 seconds ===========================

$ py.test-3 test_bug.py -s
============================= test session starts =============================
platform linux -- Python 3.4.2 -- py-1.4.25 -- pytest-2.6.3
plugins: capturelog, ordering
collected 4 items 

test_bug.py preparing bar-1
preparing bar-1/foo-1
.preparing bar-1/foo-2
.preparing bar-2
preparing bar-2/foo-2
.preparing bar-2/foo-1
.

========================== 4 passed in 0.01 seconds ===========================

I think the number of calls to a fixture should be determinstic and reproducible.

Moreover, I think the second run (where "preparing bar-1" is printed only once) is correct.

---

• Bitbucket: https://bitbucket.org/pytest-dev/pytest/issue/635

[pytestbot]

Original comment by Bruno Oliveira (BitBucket: nicoddemus, GitHub: nicoddemus):

---

Did you forget to attach test_bug.py?

[pytestbot]

Original comment by Nikolaus Rath (BitBucket: nikratio, GitHub: nikratio):

---

Indeed I did, here it is.

[pfctdayelise]

Here is what was in the test file

#!/usr/bin/env python3
import pytest

@pytest.fixture()
def foo(request, bar):
    s = '%s/foo-%d' % (bar, request.param)
    print('preparing', s)
    return s

@pytest.fixture()
def bar(request):
    s = 'bar-%d' % request.param
    print('preparing', s)
    return s

def test_one(foo):
    pass

def pytest_generate_tests(metafunc):
    foo_params = (1,2)
    bar_params = (1,2)
    if not 'foo' in metafunc.fixturenames:
        return
    assert 'bar' in metafunc.fixturenames

    metafunc.parametrize("foo", foo_params, indirect=True, scope='module')
    metafunc.parametrize("bar", bar_params, indirect=True, scope='module')

[nicoddemus]

I believe this has been fixed as I can no longer reproduce the problem. 👍