Add faker and faker_seed fixtures support (#261)

Co-authored-by: Adam Johnson <me@adamj.eu>

HISTORY.rst

@@ -2,6 +2,13 @@
 History
 -------
 
+* Provide a ``faker_seed`` fixture to set the seed for tests using faker's
+  pytest fixtures (as per its
+  `docs <https://faker.readthedocs.io/en/master/pytest-fixtures.html#seeding-configuration>`__).
+
+  Thanks to Romain Létendart for the change in `PR #261
+  <https://github.com/pytest-dev/pytest-randomly/pull/261>`__.
+
 3.3.1 (2020-04-15)
 ------------------
 

README.rst

@@ -37,7 +37,10 @@ All of these features are on by default but can be disabled with flags.
   allows for repeatable use of its random 'fuzzy' features.
 * If `faker <https://pypi.python.org/pypi/faker>`_ is installed, its random
   state is reset at the start of every test. This is also for repeatable fuzzy
-  data in tests - factory boy uses faker for lots of data.
+  data in tests - factory boy uses faker for lots of data. This is also done
+  if you're using the ``faker`` pytest fixture, by defining the ``faker_seed``
+  fixture
+  (`docs <https://faker.readthedocs.io/en/master/pytest-fixtures.html#seeding-configuration>`__).
 * If `numpy <http://www.numpy.org/>`_ is installed, its random state is reset
   at the start of every test.
 * If additional random generators are used, they can be registered under the
@@ -57,11 +60,11 @@ tests themselves, as well as giving a little more coverage to your system.
 By randomly ordering the tests, the risk of surprising inter-test dependencies
 is reduced - a technique used in many places, for example Google's C++ test
 runner `googletest
-<https://code.google.com/p/googletest/wiki/V1_5_AdvancedGuide#Shuffling_the_Tests>`_. 
-Research suggests that "dependent tests do exist in practice" and a random 
-order of test executions can effectively detect such dependencies [1]_. 
-Alternatively, a reverse order of test executions, as provided by `pytest-reverse 
-<https://github.com/adamchainz/pytest-reverse>`__, may find less dependent 
+<https://code.google.com/p/googletest/wiki/V1_5_AdvancedGuide#Shuffling_the_Tests>`_.
+Research suggests that "dependent tests do exist in practice" and a random
+order of test executions can effectively detect such dependencies [1]_.
+Alternatively, a reverse order of test executions, as provided by `pytest-reverse
+<https://github.com/adamchainz/pytest-reverse>`__, may find less dependent
 tests but can achieve a better benefit/cost ratio.
 
 By resetting the random seed to a repeatable number for each test, tests can

src/pytest_randomly.py

@@ -3,7 +3,7 @@
 import sys
 import time
 
-from pytest import Collector
+from pytest import Collector, fixture
 
 if sys.version_info >= (3, 8):
     from importlib.metadata import entry_points
@@ -239,3 +239,10 @@ def reduce_list_of_lists(lists):
     for list_ in lists:
         new_list.extend(list_)
     return new_list
+
+
+if have_faker:
+
+    @fixture(autouse=True)
+    def faker_seed(pytestconfig):
+        return pytestconfig.getoption("randomly_seed")

tests/test_pytest_randomly.py

@@ -593,6 +593,21 @@ def test_two():
     out.assert_outcomes(passed=2)
 
 
+def test_faker_fixture(ourtestdir):
+    ourtestdir.makepyfile(
+        test_one="""
+        def test_one(faker):
+            assert faker.name() == 'Ryan Gallagher'
+
+        def test_two(faker):
+            assert faker.name() == 'Ryan Gallagher'
+        """
+    )
+
+    out = ourtestdir.runpytest("--randomly-seed=1")
+    out.assert_outcomes(passed=2)
+
+
 def test_numpy(ourtestdir):
     ourtestdir.makepyfile(
         test_one="""