import subprocess

context = {}

def _save(name, value):
    context[name] = value

def _get(name):
    return context[name]

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

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

def run_echo_without_args():
    _run_echo([])

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

def exit_code_is_zero(exit_code=None):
    exit_code = int(exit_code)
    assertEqual(_get("exit_code"), exit_code)

def stdout_is_a_newline():
    assertEqual(_get('stdout'), '\n')

def stdout_is_text(text=None):
    assertEqual(_get('stdout'), text + '\n')

def stderr_is_empty():
    assertEqual(_get('stderr'), '')