Behat - Behavioral acceptance testing
Behavioral testing. Acceptance testing. Customer testing. You will also hear this referred to as BDD or Behavior Driven Development.
Behat is an automated testing system. Its strength is in behavioral testing.
Behat is the core framework used for running tests. It is capabable of testing several types of systems:
- Terminal command
- REST APIs
When you hear people talking about Behat, they're usually talking about all three components: Behat, Mink, and browser emulators.
Why Behat Versus Others?
Mainly becuase of popularity, which comes mainly from its human readability.
Getting Started with Behat
Let's use the scenario where we're ensuring that the user login experience is correct. This will verify that the site is up & running, that valid users can log in, and that invalid credentials will not work. Here's a test run, using a local development site:
And it only takes a few seconds to run.
If you run this test after a code update and find that the test fails, you know immediately that something must be fixed before it can be deployed to the production environment.
Behat tests are written in "Feature" files. They're just text files with a .feature extension on the name, instead of .txt or .php. They are usually placed in a "features" directory inside your Behat directory. More on that in the next section.
In the test run above, I was in my project's Behat directory, and ran bin/behat features/loginout.feature. That launches Behat and tells it to run the tests that are in loginout.feature. Here are the entire contents of that file:
Feature: Log in and out of the site. In order to maintain an account As a site visitor I need to log in and out of the site. Scenario: Logs in to the site Given I am on "/" When I follow "Log In" And I fill in "Username" with "admin" And I fill in "Password" with "test" And I press "Log in" Then I should see "Log out" And I should see "My account" Scenario: Logs out of the site Given I am on "/" When I follow "Log In" And I fill in "Username" with "admin" And I fill in "Password" with "test" And I press "Log in" And I follow "Log out" Then I should see "Log in" And I should not see "My account" Scenario: Attempts login with wrong credentials. Given I am on "/" When I follow "Log In" And I fill in "Username" with "badusername" And I fill in "Password" with "boguspass" And I press "Log in" Then I should see "Sorry, unrecognized username or password." And I should not see "My account"
Indentation is only for readability, and has no impact on how the tests are run.
Now let's look at each line and see what each is doing. The first few lines are essentially comments.
Feature: Log in and out of the site.
^ Name of the feature.
In order to maintain an account
As a site visitor
I need to log in and out of the site.
^ Feature itself.
Behat tests are written in the form of scenarios, and they comprise the rest of the feature file.
Scenario: Logs in to the site
^ Description of the first scenario.
Given I am on "/"
^ The context. This is the first line that is actually executed. In this case, it will load "/" (the home page) in a browser.
This (a "Given") as well as the next things ("When" and "Then") are each called a "Step."
When I follow "Log In" And I fill in "Username" with "admin" And I fill in "Password" with "test" And I press "Log in"
^ The events that need to happen. When kicks it off. And adds more events. If Behat is unable to do any of these events, the test will fail. I follow "Log In" looks for a link with the text "Log In" and clicks it. I fill in "Username" with "admin" looks for a field with the label of "Username" and types "admin" into it. I press "Log in" looks for button with the text "Log in" and presses it. Pro tip: follow is for clicking links, and press is for buttons on forms.
Then I should see "Log out" And I should see "My account"
^ The desired outcome. Then starts it, and And adds more outcomes. These are the actual tests that need to pass. Other testing frameworks often call these "assertions". I should see "Log out" looks for the text "Log out" anywhere on the page.
The other two scenarios follow the same format, as well as using not to ensure that certain things do not happen.
That's the quick walkthrough of writing scenarios, but you can dig deeper at
http://docs.behat.org/en/v2.5/guides/1.gherkin.html and find out about other aspects like
Scenario Outlines, Backgrounds and Multiline Arguments.
Get Set Up
I've looked at several resources from behat.org and elsewhere, and ended up just having to piece things together to get something that will work. I've consolidated those notes to ease the setup in the future. Behat Installation and Use.
There are a number of dependencies, so the easiest way to handle them all is to let composer do it for you. So install composer if you haven't already. On a mac, using homebrew works great:brew install composer.
Make a Behat directory, either for a project you're working on, or in a generic location. Copy thiscomposer.json file into it. Run composer install, which might take a while. It's installing Behat, Mink, several Mink extensions, and webdriver, which is for Selenium. Then run bin/behat to make sure that Behat is actually available and doing something. You should see something likeNo scenarios.
In your Behat directory, add a features folder if there's not one already, and add a something.feature file to it. You can use this loginout.feature as an example.
The last thing you need is a behat.yml file in your Behat directory. Use this behat.yml as an example, replacing the domain with the site you want to test. Also remove the selenium2 line if you're not using it.
At this point, running bin/behat in your Behat directory should run any tests located in the features directory.
Hopefully, that gets you started on your road to readable automated testing. The best resources I've found are on the behat site. You'll probably be redirected to something likehttp://docs.behat.org/en/v2.5/. Please leave a comment with your successes or other suggestions. Thanks for reading, and good luck!