import subprocess

def assertEqual(a, b):
    if a != b:
        raise Exception(
            'expected {!r} == {!r}, but was disappointed'.format(a, b))

def _run_echo(ctx, args):
    cmd = '/bin/echo'
    p = subprocess.Popen(
        [cmd] + args, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
        text=True)
    out, err = p.communicate()
    ctx["stdout"] = out
    ctx["stderr"] = err
    ctx["exit_code"] = p.returncode

def run_echo_without_args(ctx):
    _run_echo(ctx, [])

def run_echo_with_args(ctx, args=None):
    _run_echo(ctx, args.split())

def exit_code_is_zero(ctx, exit_code=None):
    exit_code = int(exit_code)
    assertEqual(ctx['exit_code'], exit_code)

def stdout_is_a_newline(ctx):
    assertEqual(ctx['stdout'], '\n')

def stdout_is_text(ctx, text=None):
    assertEqual(ctx['stdout'], text + '\n')

def stderr_is_empty(ctx):
    assertEqual(ctx['stderr'], '')