import json
from ... import application

class FakeInput(object):
    def __init__(self, fakedata):
        self.fakedata = fakedata
    def read():
        return self.fakedata

environ = json.loads(....) # Here we load bait json. If it's POST, it should contain POST body as ["postdata"]

if environ["REQUEST_METHOD"] == "POST":
    environ["wsgi.input"] = FakeInput(environ["postdata"])


result_status = None
def start_response(status, *shitargs):
    global result_status
    result_status = status

result = application(environ, start_response)

# Check expected values of result_status, maybe also result