I recently received the Python Testing Cookbook authored by Greg L. Turnquist and was happy to read about recipes on acceptance testing using Robot Framework. We’ve been using this tool at work for a few weeks now with great results. Greg shows how to test a web application using the Selenium Library extension for Robot Framework and I thought it’d be fun to demonstrate how to test a CherryPy application following his recipe. So here we go.
First some requirements:
$ mkvirtualenv --distribute --no-site-packages --unzip-setuptools acceptance (acceptance)$ pip install cherrypy (acceptance)$ pip install robotframework (acceptance)$ pip install robotframework-seleniumlibrary |
Let’s define a simple CherryPy application, which displays a input text where to type a message. When the submit button is pressed, the message is sent to the server and returned as-is. Well it’s an echo message really.
import cherrypy __all__ = ['Echo'] class Echo(object): @cherrypy.expose def index(self): return """<html> <head><title>Robot Framework Test for CherryPy</title></head> <body> <form method="post" action="/echo"> <input type="text" name="message" /> <input type="submit" /> </form> </body> </html>""" @cherrypy.expose def echo(self, message): return message if __name__ == '__main__': cherrypy.quickstart(Echo()) |
Save the code above in a module named myapp.py
Next, we create an extension to Robot Framework that will manage CherryPy. Save the following in a module CherryPyLib.py. It’s important to respect that name since Robot Framework expects the module and its class to match in names.
import imp import os, os.path import cherrypy class CherryPyLib(object): def setup_cherrypy(self, conf_file=None): """ Configures the CherryPy engine and server using the built-in 'embedded' environment mode. If provided, `conf_file` is a path to a CherryPy configuration file used in addition. """ cherrypy.config.update({"environment": "embedded"}) if conf_file: cherrypy.config.update(conf_file) def start_cherrypy(self): """ Starts a CherryPy engine. """ cherrypy.engine.start() def exit_cherrypy(self): """ Terminates a CherryPy engine. """ cherrypy.engine.exit() def mount_application(self, appmod, appcls, directory=None): """ Mounts an application to be tested. `appmod` is the name of a Python module containing `appcls`. The module is looked for in the given directory. If not provided, we use the current one instead. """ directory = directory or os.getcwd() file, filename, description = imp.find_module(appmod, [directory]) mod = imp.load_module(appmod, file, filename, description) if hasattr(mod, appcls): cls = getattr(mod, appcls) app = cls() cherrypy.tree.mount(app) else: raise ImportError, "cannot import name %s from %s" % (appcls, appmod) |
Note that we start and stop the CherryPy server during the test itself, meaning you don’t need to start it separately. Pure awesomeness.
Finally let’s write a straightforward acceptance test to validate the overall workflow of echoing a message using our little application.
***Settings***
Library SeleniumLibrary
Library CherryPyLib
Suite Setup Start Dependencies
Suite Teardown Shutdown Dependencies
Test Setup Mount Application myapp Echo
***Variables***
${MSG} Hello World
${HOST} http://localhost:8080/
***Test Cases***
Echo ${MSG}
Open Browser ${HOST}
Input text message ${MSG}
Submit form
Page Should Contain ${MSG}
Close All Browsers
***Keywords***
Start Dependencies
Setup Cherrypy
Start CherryPy
Start Selenium Server
Sleep 3s
Shutdown Dependencies
Stop Selenium Server
Exit CherryPy
Save the test above into a file named testmyapp.txt. You can finally run the test as follow:
(acceptance)$ pybot --pythonpath . testmyapp.txt |
This will start CherryPy, Selenium’s proxy server and Firefox within which the test case will be run. Easy, elegant and powerful.