Use pytest in tox

acme/setup.py

@@ -32,6 +32,7 @@ if sys.version_info < (2, 7):
 
 dev_extras = [
     'pytest',
+    'pytest-xdist',
     'tox',
 ]
 

tools/install_and_test.sh

@@ -17,5 +17,5 @@ for requirement in "$@" ; do
   if [ $pkg = "." ]; then
     pkg="certbot"
   fi
-  nosetests -v $pkg --processes=-1 --process-timeout=100
+  pytest --numprocesses auto --quiet --pyargs $pkg
 done

tox.ini

@@ -6,9 +6,6 @@
 skipsdist = true
 envlist = modification,py{26,33,34,35,36},cover,lint
 
-# nosetest -v => more verbose output, allows to detect busy waiting
-# loops, especially on Travis
-
 [base]
 # pip installs the requested packages in editable mode
 pip_install = {toxinidir}/tools/pip_install_editable.sh