Switch tests to pytest

setup.cfg

diff --git a/setup.cfg b/setup.cfg
index 5e40900..519ba68 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -1,2 +1,5 @@
 [wheel]
 universal = 1
+
+[aliases]
+test = pytest

setup.py

diff --git a/setup.py b/setup.py
index fb8b970..bf8d7d7 100644
--- a/setup.py
+++ b/setup.py
@@ -33,7 +33,8 @@
     license='Expat license',
     py_modules=['mccabe'],
     zip_safe=False,
-    test_suite='test_mccabe',
+    setup_requires=['pytest-runner'],
+    tests_require=['pytest'],
     entry_points={
         'flake8.extension': [
             'C90 = mccabe:McCabeChecker',