CP-24132: unit test for usb_scan.py

[TalonsLee]

add unit test for usb_scan.py

Signed-off-by: Xin(Talons) Li [email protected]

[mseri]

I think there are a few needed changes, one of which requires a minor refactoring in the usb_scan.py script

[mseri]

I would avoid using a file, instead I'd mock the stdout or the stderr and use print.
An example is

>>> from StringIO import StringIO
>>> def foo():
...     print 'Something'
...
>>> @patch('sys.stdout', new_callable=StringIO)
... def test(mock_stdout):
...     foo()
...     assert mock_stdout.getvalue() == 'Something\n'
...
>>> test()

from the mock documentation at http://www.voidspace.org.uk/python/mock/patch.html

However it doesn't seem that you are using the logs content at all. In that case just replace the log funciton with a void function

[TalonsLee]

OK. remove log file, and make test_log empty.

[mseri]

I think here you should also check that the failure did show the correct log error, at least the immutable part of it.
You could use @raises(SystemExit) as attribute and assert over the initial part of the error message for example

[TalonsLee]

OK.

@nottest
def test_usb_exit(self, devices, interfaces, results,
                  path="./scripts/usb-policy.conf", msg=""):
    with self.assertRaises(SystemExit) as cm:
        self.test_usb_common(devices, interfaces, results, path)
    if msg:
        self.assertIn(msg, cm.exception.message)

[mseri]

We should not copy paste the code, instead we should refactor usb_scan.py to be better suited for testing.
I think we need to extract

xen-api/scripts/usb_scan.py

Lines 627 to 637 in 3bb7471

	# match interface to device
	for i in interfaces:
	for d in devices:
	if i.is_child_of(d):
	d.add_interface(i)
	log_list(devices)
	# do policy check
	policy = Policy()
	pusbs = [to_pusb(d) for d in devices if d.is_ready() and policy.check(d)]

into a function that takes devices and interfaces as parameters and returns the object that we will serialise to json. Then this test should call that function with the mocked devices and interfaces

[TalonsLee]

OK. This will change the usb_scan.py, add a new function do_check(devices, interfaces).
I have to run more test next week.

[mseri]

Yes, call it something like make_pusbs_list(interfaces, devices) and the unit test that function

[mseri]

This is just a stylistic thing. Here and below, give meaningful names to the error functions. For example, in this case, test_usb_config_error_unexpected_characters and in the next one test_usb_config_error_duplicated_key, and so on

[TalonsLee]

done.

[mseri]

Please move these debug info logs to the main body before L648, or remove them completely