Remove import of pkg_resources for parsing pytest version (#826)

Speeds up `pytest --version` from 249ms to 204ms.

Ref: #744 (comment)

Author: blueyed

pytest_django/plugin.py

@@ -12,7 +12,6 @@
 import types
 
 import pytest
-from pkg_resources import parse_version
 
 from .django_compat import is_django_unittest  # noqa
 from .fixtures import django_assert_num_queries  # noqa
@@ -53,7 +52,8 @@
 PY2 = sys.version_info[0] == 2
 
 # pytest 4.2 handles unittest setup/teardown itself via wrapping fixtures.
-_handle_unittest_methods = parse_version(pytest.__version__) < parse_version("4.2")
+_pytest_version_info = tuple(int(x) for x in pytest.__version__.split(".", 2)[:2])
+_handle_unittest_methods = _pytest_version_info < (4, 2)
 
 _report_header = []
 

tests/test_unittest.py

@@ -1,7 +1,7 @@
 import pytest
 from django.test import TestCase
-from pkg_resources import parse_version
 
+from pytest_django.plugin import _pytest_version_info
 from pytest_django_test.app.models import Item
 
 
@@ -146,7 +146,7 @@ def test_pass(self):
         expected_lines = [
             "* ERROR at setup of TestFoo.test_pass *",
         ]
-        if parse_version(pytest.__version__) < parse_version("4.2"):
+        if _pytest_version_info < (4, 2):
             expected_lines += [
                 "E *Failed: <class 'tpkg.test_the_test.TestFoo'>.setUpClass should be a classmethod",  # noqa:E501
             ]