Unittesting cherrypy webapp

Question

I recently had to rewrite our rest api, and made the switch from Flask to Cherrypy (mostly due to Python 3 compatibility). But now I'm stuck trying to write my unit tests, Flask has a really nifty built-in test client, that you can use to sent fake requests to your application (without starting a server.) I can't find any similar functionality for Cherrypy, is there such functionality, or am I stuck starting a server and doing actual requests against it?

Answer 1

It seems that there is an alternate way to perform unittest. I just found and check the following recipe which works fine with cherrypy 3.5.

http://docs.cherrypy.org/en/latest/advanced.html#testing-your-application

    import cherrypy

    from cherrypy.test import helper

    class SimpleCPTest(helper.CPWebCase):
        def setup_server():
            class Root(object):
                @cherrypy.expose
                def echo(self, message):
                    return message

            cherrypy.tree.mount(Root())
        setup_server = staticmethod(setup_server)

        def test_message_should_be_returned_as_is(self):
            self.getPage("/echo?message=Hello%20world")
            self.assertStatus('200 OK')
            self.assertHeader('Content-Type', 'text/html;charset=utf-8')
            self.assertBody('Hello world')

        def test_non_utf8_message_will_fail(self):
            """
            CherryPy defaults to decode the query-string
            using UTF-8, trying to send a query-string with
            a different encoding will raise a 404 since
            it considers it's a different URL.
            """
            self.getPage("/echo?message=A+bient%F4t",
                         headers=[
                             ('Accept-Charset', 'ISO-8859-1,utf-8'),
                             ('Content-Type', 'text/html;charset=ISO-8859-1')
                         ]
            )
            self.assertStatus('404 Not Found')

Answer 2

I found the answer from Sylvain Hellegouarch to be super helpful in figuring this out, but it uses Python 2. I adapted their answer to use Python 3:

import io
import unittest
import urllib
import urllib.parse

import cherrypy
from cherrypy.lib import httputil

local = httputil.Host('127.0.0.1', 50000, '')
remote = httputil.Host('127.0.0.1', 50001, '')

class Root(object):
    @cherrypy.expose
    def index(self):
        return 'hello world'

    @cherrypy.expose
    def echo(self, msg):
        return msg

def setUpModule():
    cherrypy.config.update({'environment': 'test_suite'})

    # prevent the HTTP server from ever starting
    cherrypy.server.unsubscribe()

    cherrypy.tree.mount(Root(), '/')
    cherrypy.engine.start()

setup_module = setUpModule

def tearDownModule():
    cherrypy.engine.exit()

teardown_module = tearDownModule

class BaseCherryPyTestCase(unittest.TestCase):
    def webapp_request(self, path='/', method='GET', **kwargs):
        headers = [('Host', '127.0.0.1')]
        qs = fd = None

        if method in ['POST', 'PUT']:
            qs = urllib.parse.urlencode(kwargs)
            headers.append(('content-type', 'application/x-www-form-urlencoded'))
            headers.append(('content-length', f'{len(qs)}'))
            fd = io.BytesIO(qs.encode())
            qs = None
        elif kwargs:
            qs = urllib.parse.urlencode(kwargs)

        # Get our application and run the request against it
        app = cherrypy.tree.apps['']
        # Let's fake the local and remote addresses
        # Let's also use a non-secure scheme: 'http'
        request, response = app.get_serving(local, remote, 'http', 'HTTP/1.1')
        try:
            response = request.run(method, path, qs, 'HTTP/1.1', headers, fd)
        finally:
            if fd:
                fd.close()
                fd = None

        if response.output_status.startswith(b'500'):
            print(response.body)
            raise AssertionError('Unexpected error')

        # collapse the response into a bytestring
        response.collapse_body()
        return response

class TestCherryPyApp(BaseCherryPyTestCase):
    def test_index(self):
        response = self.webapp_request('/')
        self.assertEqual(response.output_status, b'200 OK')
        # response body is wrapped into a list internally by CherryPy
        self.assertEqual(response.body, [b'hello world'])

    def test_echo(self):
        response = self.webapp_request('/echo', msg='hey there')
        self.assertEqual(response.output_status, b'200 OK')
        self.assertEqual(response.body, [b'hey there'])

        response = self.webapp_request('/echo', method='POST', msg='hey there')
        self.assertEqual(response.output_status, b'200 OK')
        self.assertEqual(response.body, [b'hey there'])

Answer 3

As far as I know, CherryPy doesn't indeed provide a facility for this type of testing (no running server). But it's fairly easy to do it nonetheless (though it relies on some of the internals of CherryPy).

Here's a simple showcase:

from StringIO import StringIO
import unittest
import urllib

import cherrypy

local = cherrypy.lib.httputil.Host('127.0.0.1', 50000, "")
remote = cherrypy.lib.httputil.Host('127.0.0.1', 50001, "")

class Root(object):
    @cherrypy.expose
    def index(self):
        return "hello world"

    @cherrypy.expose
    def echo(self, msg):
        return msg

def setUpModule():
    cherrypy.config.update({'environment': "test_suite"})

    # prevent the HTTP server from ever starting
    cherrypy.server.unsubscribe()

    cherrypy.tree.mount(Root(), '/')
    cherrypy.engine.start()
setup_module = setUpModule

def tearDownModule():
    cherrypy.engine.exit()
teardown_module = tearDownModule

class BaseCherryPyTestCase(unittest.TestCase):
    def webapp_request(self, path='/', method='GET', **kwargs):
        headers = [('Host', '127.0.0.1')]
        qs = fd = None

        if method in ['POST', 'PUT']:
            qs = urllib.urlencode(kwargs)
            headers.append(('content-type', 'application/x-www-form-urlencoded'))
            headers.append(('content-length', '%d' % len(qs)))
            fd = StringIO(qs)
            qs = None
        elif kwargs:
            qs = urllib.urlencode(kwargs)

        # Get our application and run the request against it
        app = cherrypy.tree.apps['']
        # Let's fake the local and remote addresses
        # Let's also use a non-secure scheme: 'http'
        request, response = app.get_serving(local, remote, 'http', 'HTTP/1.1')
        try:
            response = request.run(method, path, qs, 'HTTP/1.1', headers, fd)
        finally:
            if fd:
                fd.close()
                fd = None

        if response.output_status.startswith('500'):
            print response.body
            raise AssertionError("Unexpected error")

        # collapse the response into a bytestring
        response.collapse_body()
        return response

class TestCherryPyApp(BaseCherryPyTestCase):
    def test_index(self):
        response = self.webapp_request('/')
        self.assertEqual(response.output_status, '200 OK')
        # response body is wrapped into a list internally by CherryPy
        self.assertEqual(response.body, ['hello world'])

    def test_echo(self):
        response = self.webapp_request('/echo', msg="hey there")
        self.assertEqual(response.output_status, '200 OK')
        self.assertEqual(response.body, ["hey there"])

        response = self.webapp_request('/echo', method='POST', msg="hey there")
        self.assertEqual(response.output_status, '200 OK')
        self.assertEqual(response.body, ["hey there"])

if __name__ == '__main__':
    unittest.main()

Edit, I've extended this answer as a CherryPy recipe.