Run functional tests in parallel (#40)

Author: GianlucaFicarelli

tox.ini

@@ -35,13 +35,13 @@ commands =
 [testenv:functional]
 setenv =
     {[testenv]setenv}
-    # Run in parallel using half of the CPUs
-    BLUEETL_JOBLIB_JOBS=
+    BLUEETL_JOBLIB_JOBS=6
 deps =
     {[base]testdeps}
+    pytest-xdist
     elephant>=0.10.0,<0.13.0  # CPDF output changed in 0.13.0
     bluepy>=2.5.2
-commands = python -m pytest -vs tests/functional {posargs}
+commands = python -m pytest -n6 -vs tests/functional {posargs}
 
 [testenv:check-packaging]
 skip_install = true