Testing Python Scripts

Question

How do I test the STDOUT output of a Python script with a testing framework like doctest, unittest, nose, etc? For example, say running my script "todo.py --list" shou

Answer 1

when you use py.test for your testing. You can use the "capsys" or the "capfd" test function arguments to run asserts against STDOUT and STDIN

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"

More details can be found in the py.test docs