Founder of Kernl.us. Working and living in Raleigh, NC. I manage a team of software engineers and work in Python, Django, TypeScript, Node.js, React+Redux, Angular, and PHP. I enjoy hanging out with my wife and son, lifting weights, and advancing Kernl.us in my free time.
TastyPie’s JSON responses split the response into two sections: meta data and actual data. The meta is really nice, because it helps you data pagination, result counts, and the like, but it kind of gets in the way of Restangular. Integrating with Restangular is easy though!
For a few hours I was running into a problem whenever I would try to install my PIP requirements file. The install would go alright until it got to Distribute, at which point I would get an that ended up in a stack trace with:
Could not find the /lib/python2.7/site-packages/site.py element of the Setuptools distribution
After much searching and digging, the issue was that my virtual environment needed to be instantiated with the –distribute flag.
I recently made the case for using the open-source WordPress CMS instead of a custom hand-rolled CMS to a manager. What follows is the email (with names and companies changed) that was sent. I thought that it might be useful to other people who are trying to convince their organization to take the leap to WordPress, Drupal, or any other open-source CMS. It’s also worth noting that I’m on very friendly terms with my manager, hence the informality and straight-forwardness. As for the Django references, we develop most of our data-driven sites in Python/Django.
Hey [Manager],
As you already know, I completely loathe the [Custom] CMS. My recent and ongoing experiences with the [Client] website have only served to reinforce these feelings. Unbridled hate rarely serves any useful purpose though, so I’ve decided to see what I can do to make the problem better. My way of doing that is by making a case for using WordPress on large, non-trivial, content driven websites. As of right now WordPress has been lasso’d into small-size websites at [Company], but I believe it is capable of far more then that. What follows is a breakdown of all the feedback, questions, and concerns that were raised while I was gathering information. I’ve provided solutions to almost all of the problems, and its worth noting that some of the problems with WordPress are not unique to WordPress. I also want to make it clear that I’m not trying to get rid of the [Custom] CMS, especially since we have a lot of clients with a lot of money invested in it. I’m simply making a case for using WordPress on large sites instead of the [Custom] CMS.
Content Creation / Management
For as long as I can remember, [Other Manager] always raised a red flag with WordPress because it was inferior in content creation to the CMS. In vanilla form this is arguably true, however WordPress has an amazing community of plugin developers surrounding it who have solved all of these problems.
Pods – I have a love-hate relationship with pods. I like that they provide nearly infinite flexibility to the content creator, but that comes with the price of nearly infinite complexity. While I disagree with giving the content-creator that much control over how content is displayed, I can see the usefulness of it. To solve that problem, there are many visual composition plugins available for WordPress. My favorite is Visual Composer (http://vc.wpbakery.com/). Extending Visual Composer (akin to adding “module functions”) is as simple as adding a hook in your WordPress widget.
Categories / Taxonomies for Media (assets) – WordPress has brilliant support for categories and custom taxonomies out of the box. Beyond that, it also has support for tags. One thing that doesn’t work out of the box is media categories. Luckily there is a large handful of community plugins that easily solve this problem for us.
Media – The media library in WordPress is extremely slick, ajax-y (asynchronous uploads, etc), and easily extendable. Multiple thumbnails and image sizes are generated out of the box. Adding new image sizes is easy too.
Videos – WordPress supports videos out of the box. Adding Youtube/Hulu/Vimeo videos is as easy as adding one of the numerous plugins. There are even plugins out there that interface with FFMPEG to get you a nice selection of thumbnails to choose from.
Form Builder – The new hotness of [Custom] CMS is Form Builder. WordPress has a large amount of awesome form builders available, and most of them are cheap and come with support. Gravity Forms(http://www.gravityforms.com) is my favorite. Although Ninja forms is looking like a valid alternative.
User Management – WordPress comes with excellent user management out of the box. It has 4 default roles (Administrator, Editor, Contributor, Subscriber), but no way to change what those roles are capable of. They generally have pretty sane defaults, but sometimes you want to tweak things. User Role Editor(http://wordpress.org/plugins/user-role-editor) provides an easy way to modify group and user permissions. If you need to add new roles, there are plugins for that as well.
Content Deployment – We’ve often struggled with how to deploy new content to sites. Generally you don’t want to create the content on live, because it will need to be hidden. There is a straight ballin’ plugin for WordPress called Ramp(http://crowdfavorite.com/wordpress/ramp/) that solves this problem. Seriously, check this out. It will blow your mind.
General Notes
I have a handful of notes that don’t fit well into Content Creation / Management or Development, so here we go.
Update Cycle – WordPress has a release cycle (http://en.wikipedia.org/wiki/WordPress#Releases). It has feature releases, bug releases, and HOLY HELL THATS A BIG RELEASE releases. WordPress updates are vetted by an insanely large community of professional developers who catch bugs/regressions and fix them before release.
CMS “Upgrades” – Somehow its become normal and accepted at [Company] that a CMS Upgrade costs north of $25,000, takes a month, and almost always ends up braking some part of the site that wasn’t broken before. WordPress upgrades take 10 seconds, don’t break changes, and have deprecation warnings just in case you’re using a method/hook that won’t be supported in a future release. We might make some money off of [Custom] CMS upgrades, but my experience has been that they end up costing more time/effort/good will then they are worth. Having a one-click upgrade option allows us to keep our sites secure, up to date, and gets us back to making things awesome.
Community – WordPress.org has 1,998 base themes that can be used and extended via theme inheritance. It also has over 26,000 plugins that extend WordPress’ functionality. This doesn’t account for the numerous premium plugins that are available throughout the internet. Help is always just a Google search away. If that doesn’t work, Stack Overflow most certainly will. Having the backing of a community while you are developing is invaluable. Did I mention the WordPress IRC channel?
Documentation – One of the most frustrating things about the [Custom] CMS isn’t the lack of code documentation, but the lack of code usage documentation. WordPress has a ludicrous amount of documentation on pretty much anything you can think of. It stays up to date with best practices and is updated for every release. If the WordPress.org documentation isn’t good enough, the source code is very well documented. If the source doesn’t suit your fancy, there is probably a blogger that wrote about your problem.
Hiring – Hiring is hard in this economic climate. Selling a PHP developer to come work for [Company] with [Custom] CMS is even harder. If the person is a WordPress expert, all of that domain knowledge stagnates and becomes useless here. It also makes the on-boarding process take 2-4 months. And even then, they still aren’t all that useful in the [Custom] CMS. Having WordPress as a core tool allows us to hire people who are already experts. The on-boarding becomes a few weeks, and everyone is happy. It also makes it a lot less fatal if we lose a developer, because it’s possible to hire another one that already has all the domain knowledge.
Focus – Using WordPress is similar to using Django in that it gets out of your way at lets you focus on what’s important: making awesome stuff. You don’t have to piddle around with random regressions, bugs, or odds and ends. Those are already worked out for you. You get to focus on making custom functionality the best you can. Not having to mess around with bugs and regressions allows you to focus on quality instead of just “getting it done”.
Security – WordPress can be a security nightmare. With an install footprint of over 60 million websites (as of 2012), everybody is trying to hack it. Luckily most plugin authors and the WordPress security team are always right on top of it. There is a plugin called WP Security Scan(http://wordpress.org/plugins/wp-security-scan/) that takes care of making sure all the directories have the proper permissions, and in general gives good advice to harden your WordPress installation. Taking 10 minutes a week to update all your WordPress sites is also the best way to prevent security issues.
Who? – WordPress.com has a nice list of notable WordPress users (http://en.wordpress.com/notable-users/). The list includes, CNN, NYTimes, Forbes, Reuters, Sony, Jay-Z, Rolling Stones, GM, and others.
Cost – We keep upgrading the CMS. It needs it, but it cost lots of money. WordPress and the open-source community keep things up-to-date for us, so the cost is nil.
Development
In the past, a lot of misinformation has been spread about WordPress and how developing with it is awful. A lot of that comes from lack of knowledge, so I thought I’d address a lot of the pain points that people have experienced.
Plugin Creation – [Other developer] brought up the point that WordPress plugins are created in a procedural fashion, and are therefore a huge PITA to work with. As it turns out, the correct way to make WordPress plugins is via OOP. This NetTuts tutorial covers most of the basics (http://net.tutsplus.com/tutorials/wordpress/create-wordpress-plugins-with-oop-techniques/).
Content Deployment – WordPress hard-codes URLs into the database content. This is obviously a bad idea for many reasons. To rectify, if you move content from one server to another, you just need to execute 3 sql queries as part of your deployment. Usage of Ramp (mentioned above) solves this issue for 99% of use cases.
Versioning – WordPress shouldn’t be versioned. Any plugin you install from WordPress.org should not be versioned. If you are making a custom theme, that should get it’s own repository (hey, look at Stash and all it’s repos we can create). If you are making a custom plugin, that should also get it’s own repo. This promotes re-usability and good coding practices. Deployment of theme/plugin updates is as easy as checking out the latest version or git-pulling.
Deployment – Initial deployment of a WordPress site is just like moving a staging site to the live server for the [Custom] CMS. After that, deploying code updates to custom plugins and themes is just a git pull/checkout of a tag. This could easily be streamlined with the use of Fabric or Capistrano.
Modules / Custom Post Types – The [Custom] CMS has a pretty nice way of creating basic custom content via modules and the scaffolding. WordPress has custom post types, and several different plugins for creating them on the fly. My current favorite is Advanced Custom Fields (http://www.advancedcustomfields.com/)
Theme Inheritance – As mentioned before, WordPress has LOTS of themes. Nearly any one of them can be used as a base theme, saving front-enders a ton of time getting base CSS and templates set up.
ORM – WordPress has a weak ORM. Hopefully you can use WordPress’ features enough that you can write minimal SQL. On the bright side, you’ll have some nicely optimized queries 😉 This is also why you should use the right tool for the job. If you have to interact with the database so much that you need an ORM, you should probably be using a framework.
Testing – WordPress core is fully unit and integration tested. The majority of premium plugins and popular plugins are tested as well. Plugins can easily be tested using PHPUnit, and their interfaces can be tested using Behat.
Developing as a Team – WIth a sane Git strategy (custom plugins and themes versioned only) developing as a team is a non-issue. In the past, having the whole project under version control caused serious issues when there was more then one developer.
Database Migrations – Just as with [Custom] CMS, if you have complex migration that destroys data you’ll need to handle the migration yourself. http://codex.wordpress.org/Creating_Tables_with_Plugins has more info. If the migration isn’t destructive, you can use the wp_delta method to handle it for you.
Environment Abstraction – WordPress does a great job of not caring about what version of PHP you’re on. So long as you are PHP >= 5.2.4 and MySQL >= 5.0.0, you’re all set
I know we’ve talked in the past about vetting a Django CMS, but I think that using WordPress is the best choice. We already have people who know it, the front-enders know how to develop for it, the community is massive, and learning it is easy. I look forward to talking with you about this.
The Ruby on Rails community has long been a proponent of Behavior Driven Development(BDD) and has a great ecosystem around it supporting that testing methodology. From Cucumber to Capybara, RoR developers have it made when it comes to BDD. But what about Django? What about Python? Django and Python don’t have access to Cucumber or Capybara, but what we do have is a fantastic port of Cucumber called Lettuce.
What is Behavior Driven Development
Before we can get started talking about Lettuce and all the cool things you can do with it, we first need to talk about BDD.
Behavior-driven development combines the general techniques and principles of TDD with ideas from domain-driven design and object-oriented analysis and design to provide software developers and business analysts with shared tools and a shared process to collaborate on software development. (Wikipedia)
BDD arose out of the need for the business side of software and the engineering side of software to communicate more effectively. Prior to BDD, it was a lot more difficult to communicate the business requirements of a project to developers. Sure there were spec documents, but those still needed to be translated into a language the computer can understand. With BDD, tests and acceptance criteria are more accessible to everybody involved. Dan North suggested a few guidelines for BDD, and then the development community took it from there.
Tests should be grouped into user stories. Essentially narratives about the expected functionality.
Stories should have a title. The title should be clear and explicit.
There should be a short narrative at the beginning of the story, that explains who the primary stakeholder of the story is, what effect the story should have, and what business value the stakeholder derives from this from this effect.
Scenarios(tests) should follow the format of first describing the initial conditions for the scenario, then which event(s) triggers the start of the scenario, and finally what the expected outcome of the scenario should be.
All of these steps should be written out in natural language, preferably using the Gherkin syntax.
An example feature using Gherkin.
Feature: Authentication
In order to protect private information
As a registered user
I want to log in to the admin portal
Scenario: I enter my password correctly
Given the user "Jack" exists with password "password"
And I am at "/login/"
When I fill in"Login" with "Jack"
And I fill in"Password" with "password"
And I press "Login"
Then I should be at "/portal/"
And I should see "Welcome to the admin portal"
Feature: Authentication
In order to protect private information
As a registered user
I want to log in to the admin portal
Scenario: I enter my password correctly
Given the user "Jack" exists with password "password"
And I am at "/login/"
When I fill in "Login" with "Jack"
And I fill in "Password" with "password"
And I press "Login"
Then I should be at "/portal/"
And I should see "Welcome to the admin portal"
So now that we know the gist of BDD, why would you want to use it? There are probably more reasons than the 3 I’m going to list, but I found these to justify my use of BDD in most cases.
It’s easy for business minded people to understand what you’re trying to test.
It’s easier to translate complicated business requirements into tests.
Some things are easier to explain in natural language.
Alright, now we’re done with the background information. Let’s get rolling on some testing.
Getting Started
To follow the rest of this article, you’re going to need the following:
A little Python experience
A little Django experience
Extremely basic knowledge of regular expressions
Knowledge of how to set up a virtual environment using virtualenv (I also use virtualenvwrapper to make my life a bit easier)
Firefox – Yes, I know you don’t need Firefox to do this, but its probably the easiest to use with Selenium.
On the bright side, no previous testing experience required!
The best place to start with all this getting the virtual environment set up.
And now we’ll need to create a new Django project.
(learning_lettuce)jack:repos jacks$ django-admin.py startproject learning_lettuce
(learning_lettuce)jack:repos jacks$ cd learning_lettuce/(learning_lettuce)jack:learning_lettuce jacks$ ls-la
total 8
drwxr-xr-x 4 jacks staff 136 Jun 19 07:50 .
drwxrwxrwx 28 jacks staff 952 Jun 19 07:50 ..
drwxr-xr-x 6 jacks staff 204 Jun 19 07:50 learning_lettuce
-rw-r--r--1 jacks staff 259 Jun 19 07:50 manage.py
(learning_lettuce)jack:repos jacks$ django-admin.py startproject learning_lettuce
(learning_lettuce)jack:repos jacks$ cd learning_lettuce/
(learning_lettuce)jack:learning_lettuce jacks$ ls -la
total 8
drwxr-xr-x 4 jacks staff 136 Jun 19 07:50 .
drwxrwxrwx 28 jacks staff 952 Jun 19 07:50 ..
drwxr-xr-x 6 jacks staff 204 Jun 19 07:50 learning_lettuce
-rw-r--r-- 1 jacks staff 259 Jun 19 07:50 manage.py
At this point, I also like to CHMOD manage.py so I can execute it without calling Python directly.
(learning_lettuce)jack:learning_lettuce jacks$ chmod +x manage.py
(learning_lettuce)jack:learning_lettuce jacks$ ./manage.py runserver
Validating models...
0 errors found
June 19, 2013 - 06:53:29
Django version 1.5.1, using settings 'learning_lettuce.settings'
Development server is running at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
(learning_lettuce)jack:learning_lettuce jacks$ chmod +x manage.py
(learning_lettuce)jack:learning_lettuce jacks$ ./manage.py runserver
Validating models...
0 errors found
June 19, 2013 - 06:53:29
Django version 1.5.1, using settings 'learning_lettuce.settings'
Development server is running at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
If you can run the server and see the image below, then we can proceed.
Now that we have Django set up, lets go ahead and create the app we’ll be testing in.
(learning_lettuce)jack:learning_lettuce jacks$ ./manage.py startapp blog
(learning_lettuce)jack:learning_lettuce jacks$ ./manage.py startapp blog
And then go ahead and add the blog app to INSTALLED_APPS in your settings.py file.
Now that we have a Django project and one app set up, its time to take a break and talk about Lettuce.
Lettuce
No, not the vegetable you add to salads. I’m talking about the the BDD testing framework for Python (http://www.lettuce.it). Lettuce is basically a port of a BDD testing framework from the RoR community called Cucumber. The Lettuce website contains extensive documentation and is a great source for learning best practices with it. It’s worth noting however, that at the time of this writing the Lettuce website is undergoing some design changes. They’re incomplete and have made it pretty hard to extract information from the site. Hopefully by the time you need it for reference it’s back to being usable again.
Alright, back to work. Lets install Lettuce, Selenium, and Nose and then freeze a requirements file so we can replicate this environment if we ever need to.
So now that you have Lettuce installed, lets see that it actually works.
(learning_lettuce)jack:learning_lettuce jacks$ ./manage.py harvest
Django's builtin server is running at 0.0.0.0:8000
Oops!
could not find features at ./blog/features
(learning_lettuce)jack:learning_lettuce jacks$ ./manage.py harvest
Django's builtin server is running at 0.0.0.0:8000
Oops!
could not find features at ./blog/features
Great, Lettuce worked! It didn’t find any tests to run, but thats ok. At least we’ve verified that we installed everything correctly.
Your First Test
Before you can test anything, you should probably have some content to test on. So let’s quickly wire up a simple view in the blog app.
# learning_lettuce/urls.py
from django.conf.urls import patterns, include, url
from blog.views import quick_test
urlpatterns = patterns('',
url(r'^quick-test/$', quick_test),
)
Great! Now when you go to http://127.0.0.1:8000/quick-test/ you should see “Hello testing world!”.
The next step is to create a folder inside of the blog app called “features”. And inside of that create a file called “test.feature”. It’s worth noting that Lettuce doesn’t actually care what your file is named, so long as the extension is “.feature”. In “test.feature”, add the following:
Feature: Test
As someone new to testing
So I can learn behavior driven development
I want to write some scenarios
Scenario: I can view the test page
Given I am at "/quick-test/"
Then I should see "Hello testing world!"
Feature: Test
As someone new to testing
So I can learn behavior driven development
I want to write some scenarios
Scenario: I can view the test page
Given I am at "/quick-test/"
Then I should see "Hello testing world!"
Look at all that plain english! Even without me telling you anything, you can probably figure out what we’re trying to test. But let me break it down for you.
Line 1: This loosely describes what all of the scenarios below are testing. Think of it as a way to logically group tests together.
Lines 2-4: This is the narrative. It explains why you’re testing in the first place.
Line 6: The title of your scenario. This describes what you are specifically testing in this instance.
Lines 7-8: These are called “steps”. Steps are how you test your scenario. Each step maps to a method in your code.
Alright, so now that you have your first test written, run it using “./manage.py harvest”. You should see the following:
Look at all that beautiful output! But what does it all mean?! It’s telling you that Lettuce attempted to run one scenario, and that the two steps within that scenario aren’t implemented yet (remember, each step maps to a method in your code). And because Lettuce is great, it gives you some code to help you implement those two steps.
The Terrain File
Lettuce keeps all of it’s settings and configuration is a file called terrain.py in the root of your Django project. It’s here that we’re going to configure the test database, Firefox, and Selenium. Go ahead and create a terrain.py file in the root of your Django project, and drop the following in it.
from django.core.managementimport call_command
from django.test.simpleimport DjangoTestSuiteRunner
from lettuce import before, after, world
fromloggingimport getLogger
from selenium import webdriver
try:
from south.management.commandsimport patch_for_test_db_setup
except:
pass
logger = getLogger(__name__)
logger.info("Loading the terrain file...")@before.runserverdef setup_database(actual_server):
'''
This will setup your database, sync it, and run migrations if you are using South.
It does this before the Test Django server is set up.
'''
logger.info("Setting up a test database...")# Uncomment if you are using South# patch_for_test_db_setup()
world.test_runner= DjangoTestSuiteRunner(interactive=False)
DjangoTestSuiteRunner.setup_test_environment(world.test_runner)
world.created_db= DjangoTestSuiteRunner.setup_databases(world.test_runner)
call_command('syncdb', interactive=False, verbosity=0)# Uncomment if you are using South# call_command('migrate', interactive=False, verbosity=0)@after.runserverdef teardown_database(actual_server):
'''
This will destroy your test database after all of your tests have executed.
'''
logger.info("Destroying the test database ...")
DjangoTestSuiteRunner.teardown_databases(world.test_runner, world.created_db)@before.alldef setup_browser():
world.browser= webdriver.Firefox()@after.alldef teardown_browser(total):
world.browser.quit()
from django.core.management import call_command
from django.test.simple import DjangoTestSuiteRunner
from lettuce import before, after, world
from logging import getLogger
from selenium import webdriver
try:
from south.management.commands import patch_for_test_db_setup
except:
pass
logger = getLogger(__name__)
logger.info("Loading the terrain file...")
@before.runserver
def setup_database(actual_server):
'''
This will setup your database, sync it, and run migrations if you are using South.
It does this before the Test Django server is set up.
'''
logger.info("Setting up a test database...")
# Uncomment if you are using South
# patch_for_test_db_setup()
world.test_runner = DjangoTestSuiteRunner(interactive=False)
DjangoTestSuiteRunner.setup_test_environment(world.test_runner)
world.created_db = DjangoTestSuiteRunner.setup_databases(world.test_runner)
call_command('syncdb', interactive=False, verbosity=0)
# Uncomment if you are using South
# call_command('migrate', interactive=False, verbosity=0)
@after.runserver
def teardown_database(actual_server):
'''
This will destroy your test database after all of your tests have executed.
'''
logger.info("Destroying the test database ...")
DjangoTestSuiteRunner.teardown_databases(world.test_runner, world.created_db)
@before.all
def setup_browser():
world.browser = webdriver.Firefox()
@after.all
def teardown_browser(total):
world.browser.quit()
In your settings.py file, you’re going to need some additions too.
# Nose
TEST_RUNNER ='django_nose.NoseTestSuiteRunner'# Lettuce
LETTUCE_SERVER_PORT =9000
# Nose
TEST_RUNNER = 'django_nose.NoseTestSuiteRunner'
# Lettuce
LETTUCE_SERVER_PORT = 9000
We use the Nose test runner because it’s faster than Django’s default test runner, and we change the server port for running tests so it doesn’t collide with our development server. At this point if you run `./manage.py harvest` again, you’ll still get notices for unimplemented steps, but you’ll also see Firefox open and close real quick. That means we’ve done our job correctly.
Your First Step Definition
Alright, lets make something happen. If you look at the output from the harvest command, you’ll see that it gave you some code to help you implement the new steps that you wrote. Go ahead and copy that code into the bottom of the terrain.py file (and make sure to import ‘step’ at the top). Now, re-run ./manage.py harvest. You should get the following output.
So why did our steps fail? If you look that the code that was generated for you, there is a line that essentially says “False is equal to some string”. This is obviously not true, so our step fails. So why don’t we make the test pass? We’re going to change a few things:
Change the decorator – We want this step to match even if we use other Gherkin keywords like “when”, “and”, and “then”.
Change the function name and args – “group1” isn’t very descriptive
Write the code – We need this to do something, and right now it doesn’t!
@step(u'I am at "([^"]*)"')def i_am_at_url(step, url):
world.browser.get(url)
@step(u'I am at "([^"]*)"')
def i_am_at_url(step, url):
world.browser.get(url)
Now if you run ./manage.py harvest command again your tests will still fail, but this time for a different reason. The reason is the url that we’re passing into the step definition isn’t well formed. We were hoping to be able to pass relative urls in, but we can’t. So go ahead and modify the step in your scenario to look like this.
Given I am at "http://127.0.0.1:9000/quick-test/"
Given I am at "http://127.0.0.1:9000/quick-test/"
Run ./manage.py harvest again. You’ll see one passing test and one failing test!
To make the next step pass, we need to make our web page a bit more formal. Go ahead and create a folder called “templates” inside of the “blog” app. Inside that folder, add a file called “base.html” and populate it with:
from django.shortcutsimport render_to_response
def quick_test(request):
return render_to_response("blog.html",{})
from django.shortcuts import render_to_response
def quick_test(request):
return render_to_response("blog.html", {})
And you’ll need to update your settings file.
## Add this at the top of settings.pyimportos.path
root =os.path.dirname(__file__).replace('\\','/')## Make your TEMPLATE_DIRS variable look like this
TEMPLATE_DIRS =(
root + "/../blog/templates/",)
## Add this at the top of settings.py
import os.path
root = os.path.dirname(__file__).replace('\\','/')
## Make your TEMPLATE_DIRS variable look like this
TEMPLATE_DIRS = (
root + "/../blog/templates/",
)
Now that our template is more formalized, lets update the step definition in “terrain.py”.
@step(u'I should see "([^"]*)"')def i_should_see_content(step, content):
if content notin world.browser.find_element_by_id("content").text:
raiseException("Content not found.")
@step(u'I should see "([^"]*)"')
def i_should_see_content(step, content):
if content not in world.browser.find_element_by_id("content").text:
raise Exception("Content not found.")
This code explains itself pretty easily. We check to see if the content that is passed in via the step exists inside the body of the page. This has a few drawbacks:
What if we don’t want to check the body? What if we want to check a different element?
What if the content isn’t visible? (CSS hidden)
Since this is a simple example, we’re going to ignore these issues for now and just run our tests.
Passing tests!
Next Steps
Now that you have passing steps, you’re well on your way to writing serious integration tests for your code. But there is still a lot more to learn. The next article in this series will cover using Lettuce Webdriver to handle common step definitions, tables, scenario outlines, and much much more.
Lettuce is a BDD (Behavior Driven Development) testing tool for Python based on the excellent Cucumber project. It has most of the same features that Cucumber has, and has proven invaluable in my projects. I discovered an undocumented feature the other day called “Tags”. Cucumber has them, so I also assumed that Lettuce had them. Tags allow you to selectively skip or run scenarios. For instance:
Feature: Some Feature
Scenario: This is scenario 1
Given I do stuff
And I see stuff
Then I am stuff
@mytag
Scenario: This is scenario 2
Given I do more stuff
And I see more stuff
Then I am more stuff
Feature: Some Feature
Scenario: This is scenario 1
Given I do stuff
And I see stuff
Then I am stuff
@mytag
Scenario: This is scenario 2
Given I do more stuff
And I see more stuff
Then I am more stuff
You can use tags in many ways.
lettuce --tag=mytag # Run only scenarios with this tag
lettuce --tag=-mytag # Don't run scenarios with this tag
./manage.py harvest --tag=mytag # Django/Lettuce way of using tags.
There is a grand myth about requirements–if you write them down, users will get exactly what they want. That’s not true. At best, users will get exactly what was written down, which may or may not be anything like what they really want.
– Mike Cohn, “Succeeding with Agile”
One of the more useful features of the Django framework is it’s extensive signaling capabilities. The ORM throws off a handful of signals every time a model is initialized, modified, saved, or deleted. They include:
pre_init
post_init
pre_save
post_save
pre_delete
post_delete
m2m_changed
class_prepared
I tend to use the post_save signal fairly often as a good way to get around overriding the default save method on models. Recently though I ran into an issue where I was hitting the “maximum recursion depth exceeded” error when I was saving the current model from within the post_save signal. If you think about it, that makes a lot of sense. You save once, then save again in the signal and then it triggers the signal again. BOOM, infinite loop.
To get around the saving within a post_save signal problem, you just need to disconnect the post_save signal before you call save. After save, you can re-connect it.
from django.db.modelsimport signals
signals.post_save.disconnect(some_method, sender=SomeModel)
some_instance.save()
signals.post_save.connect(some_method, sender=SomeModel)
from django.db.models import signals
signals.post_save.disconnect(some_method, sender=SomeModel)
some_instance.save()
signals.post_save.connect(some_method, sender=SomeModel)
I recently needed to add a large number of users to a permission group in Django. I had a hard time finding a way to do this in the documentation, so I thought I’d share my solution.
from django.contrib.auth.modelsimport Group, User
g = Group.objects.get(name='My Group Name')
users = User.objects.all()for u in users:
g.user_set.add(u)
from django.contrib.auth.models import Group, User
g = Group.objects.get(name='My Group Name')
users = User.objects.all()
for u in users:
g.user_set.add(u)
Easy as pie. I originally attempted to do this from the perspective of a user, but as it turns out, doing it from the group perspective is much easier.
