Strange testcase in test_yq_arg_handling

[iv-m]

test_yq_arg_handling has the following line:

self.run_yq("{}", [], expect_exit_codes={0} if sys.stdin.isatty() else {2})

As far as I understood, that exit code selection should match this part of cli(...):

if sys.stdin.isatty() and not args.input_streams:
    parser.print_help()
    sys.exit(2)

But it does not, because:

• the condition is reversed (it should be 2 when stdin is a TTY, not vice versa)
• stdin is not a TTY in this test anyway, as sys.stdin is replaced with StringIO in run_yq method

So the test fails whenever it's run with non-TTY stdin, e.g. '< /dev/null' or in some automated build environment.