如何使用 pytest 和 python 测试控制台打印？

Question

I would like to test the print of a function with unitest on python 2.7:

Example:

def load_parse_xml(data_file):
    if os.path.isfile(data_file):
        print "Parsing..."
        data_parse = ET.ElementTree(file=data_file)
        return data_parse.getroot()
    else:
        print data_file + " --> File not exist"

In the example I want to test that we have "Parsing..." in the console

here is my test:

def test_load_parse_xml(self):
    data_file = os.getcwd() + "/xml_tests/xmltest.xml"
    load_parse_xml(data_file)
    .......

But then I don't know how to test what is written "Parsing..." in the console. I am blocked

I just want to test if we have the same message in the console as "Parsing..."

Answer 1

You can use capsys from pytest.

See also: https://docs.pytest.org/en/6.2.x/capture.html#accessing-captured-output-from-a-test-function

You could do something like this:

def test_test(capsys):
    print("Your print out from load_parse_xml")
    captured = capsys.readouterr()
    assert captured.out.strip() == "Your print out from load_parse_xml"