Make virtuelenv testable

smoke/venv.sh

@@ -3,12 +3,21 @@
 # set python version
 VERSION=${VERSION:-3.7}
 PYTHON=python$VERSION
+METHOD=${METHOD:-venv}
 
 # clean from possible older runs
 rm -rf venv .tox __pycache__ .pytest* test_*.py *.pyx *.c *.so || :
 
 # check the we can create the venv
-$PYTHON -m venv venv
+if [ "$METHOD" == "venv" ]; then
+  $PYTHON -m venv venv
+elif [ "$METHOD" == "virtualenv" ]; then
+  virtualenv --python=$PYTHON venv
+else
+  echo 'Unsupported $METHOD' $METHOD >&2
+exit 1
+fi
+
 
 # and activate it
 # unset variables on 3.5, it's known