\'\'\'
http://pytest.org/2.2.4/capture.html
\'\'\'
def test_myoutput(capsys): # or use "capfd" for fd-level
print ("hello")
sys.stderr.write("world\\n")
out, err = capsys.readouterr()
assert out == "hello\\n"
assert err == "world\\n"
print "next"
out, err = capsys.readouterr()
assert out == "next\\n"