BDD - you're doing it all wrong!
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The document discusses best practices for Behavior Driven Development (BDD) and provides examples of poor and good implementations. Some key points: - It identifies common anti-patterns in BDD implementations like focusing on technical implementation details rather than business needs or writing brittle tests coupled to UI elements. - Good BDD specifies requirements in a common language understood by all stakeholders and leads to executable specifications with examples for features that deliver business value. - It recommends approaches like page objects to encapsulate page actions and hide implementation details, as well as using context objects and examples tables for clearer, more maintainable specifications.
BDD - you're doing it all wrong!
- 1. Andrew Larcombe @andrewl BDD? You’re doing it all wrong! (perhaps)
- 2. Who am I?! Software Delivery Professional" Engineering: Drupal (nodejs, go-lang, solr, geospatial, ruby-on-rails, perl, c++) Process: Agile, Scrum, BDD" t: @andrewl w: andrewl.net e: andrew@andrewl.net" " fluxus.io
- 3. " " What is Behavioural Driven Development? Some common anti-patterns
- 5. “BDD is a second-generation, outside–in, pull-based, multiple- stakeholder, multiple-scale, high- automation, agile methodology.” (Dan North)
- 7. The Problem! We have complex communication problems, not technical problems (mostly)." Jargon, ‘Chinese Whispers’, early solutionising" Consequences: Locked in to delivering late, delayed or the wrong product, before we’ve even written a line of code.
- 9. “If I asked my customers what they wanted they would have said ‘a faster horse’” (Henry Ford)
- 10. Behat
- 11. Requirement Conversation Discovery Specification Automation For all, in a common language Behat
- 12. BDD leads to Executable Specifications with Examples for features that deliver business value and that are written in the domain language of the business! " Behat is a tool for automating these specifications.!
- 13. Some BDD & Behat Antipatterns
- 14. " All journeys sold between Brussels and Chicago with a child ticket should have at least one accompanying adult or senior ticket.
- 15. As a user I want to be prevented from purchasing a child only journey from Brussels to Chicago So that…errr…??? Antipattern #1: “As a User”!
- 16. As the Company Lawyer I want to prevent customers purchasing a child only ticket on flights from Brussels to Chicago So that we’re compliant with regulations This is the person that cares This is why they care
- 17. Given I go to ‘/tickets.php’ And I select ‘0’ from ‘xpath://ticket-form/adults’ And I select ‘2’ from ‘xpath://ticket-form/children’ And I select ‘0’ from ‘xpath://ticket-form/youths’ And I select ‘0’ from ‘xpath://ticket-form/seniors’ And I click ‘xpath://ticket-form/submit’ Then I should see “You cannot purchase child-only tickets for this journey” And I should be on ‘/tickets.php’ Antipattern #2: “Writing Brittle Tests not Specifications”!
- 18. Tight coupling with DOM Tight coupling with URLs Hard-coded messages?!?!! Given I go to ‘/tickets.php’ And I select ‘0’ from ‘xpath://ticket-form/adults’ And I select ‘2’ from ‘xpath://ticket-form/children’ And I select ‘0’ from ‘xpath://ticket-form/youths’ And I select ‘0’ from ‘xpath://ticket-form/seniors’ And I click ‘xpath://ticket-form/submit’ Then I should see “You cannot purchase child-only tickets for this journey” And I should be on ‘/tickets.php’ Repetition Who even understands this??!?!! Antipattern #2: “Writing Brittle Tests not Specifications”!
- 19. Given I am on the ticket search page When search for tickets from “<origin>” to “<destination>” for “<num_adults”> adults, “<num_children>” children and “<num_seniors> seniors Then I should see the child fare policy message And be on the ticket search page Examples: |origin |destination|num_adults|num_children|num_seniors| |Brussels|Chicago |0 |1 |0 | |Brussels|Chicago |0 |2 |0 | |Brussels|Chicago |0 |3 |0 | |Brussels|Chicago |0 |4 |0 | |Brussels|Chicago |0 |5 |0 |
- 20. Page Objects! Separation of Concerns" Encapsulation" DRY (Don’t Repeat Yourself)" Hides implementation details" An API for the things you do on a page" e.g. class TicketSearchPage: it’s where you search for tickets (that’s what you do on the ticket search page)
- 21. § class SearchPage function search($origin, $dest, …) { $this->get(‘Search Form’) ->setOrigin($origin); function warningMessage() { return $this->get class SearchForm { function setOrigin($origin) { $this ->fillField(“From”, $origin); …etc… class SearchContext { function iShouldSeePolicyMessage() { expect($this->getPage(‘search’)->warningMessage())->toBe(‘You cannot purchase child-only tickets for this journey’) …Page Object Contexts Hide the Complexity - Feature Contexts…
- 22. Page Objects…an approach! Start with wireframe/ui." " Describe in English what you do on the page." " Write a function in your Page object that maps onto a ‘real world’ action that you might perform on the page" eg search(), register(), uploadAnImage(), addAComment()." " Write a function in your Context that maps requirements into these actions and throws exceptions where required." " Refactor, refactor, refactor
- 23. " All journeys sold between Brussels and Capetown with 2 or more child tickets should have at least one accompanying adult or senior ticket.
- 24. Given I am on the ticket search page When search for tickets from “<origin>” to “<destination>” for “<num_adults”> adults, “<num_children>” children and “<num_seniors> seniors Then I should see the child fare policy message And be on the ticket search page Examples: |origin |destination|num_adults|num_children|num_seniors| |Brussels|Chicago |0 |1 |0 | |Brussels|Chicago |0 |2 |0 | |Brussels|Chicago |0 |3 |0 | |Brussels|Chicago |0 |4 |0 | |Brussels|Chicago |0 |5 |0 | |Brussels|Capetown |0 |2 |0 | |Brussels|Capetown |0 |3 |0 | |Brussels|Capetown |0 |4 |0 | |Brussels|Capetown |0 |5 |0 |
- 25. " Add some front-end validation…after the user selects the origin and destination, load the rules determining child ticket policies using AJAX
- 26. Given I go to ‘/tickets.php’ And I select ‘Brussels’ from ‘xpath://ticket-form/ origin’ And I select ‘Chicago’ from ‘xpath://ticket-form/ destination’ And I wait 3 seconds
- 27. Given I go to ‘/tickets.php’ And I select ‘Brussels’ from ‘xpath://ticket-form/ origin’ And I select ‘Chicago’ from ‘xpath://ticket-form/ destination’ And I wait 5 seconds Never part of anyone’s specification, ever! Antipattern #3: “And I wait…”!
- 28. public function spin ($lambda) { while (true) { try { if ($lambda($this)) { return true; } } catch (Exception $e) { //and do nothing here } sleep(1); //wait and try again in a second } } $this->spin(function($context) { $context->getSession()->getPage()->findById('adults'); }); " Spin functions!
- 29. In review…not writing tests, discovering the specification
- 30. As a user I want to be prevented from purchasing a child only journey from Brussels to Chicago So that…errr…???
- 31. As the Company Lawyer I want to prevent customers purchasing a child only ticket on flights from Brussels to Chicago So that we’re compliant with regulations
- 32. Given I go to ‘/tickets.php’ And I select ‘0’ from ‘xpath://ticket-form/adults’ And I select ‘2’ from ‘xpath://ticket-form/children’ And I select ‘0’ from ‘xpath://ticket-form/youths’ And I select ‘0’ from ‘xpath://ticket-form/seniors’ And I click ‘xpath://ticket-form/submit’ Then I should see “You cannot purchase child-only tickets for this journey” And I should be on ‘/tickets.php’
- 33. Given I am on the ticket search page When search for tickets from “<origin>” to “<destination>” for “<num_adults”> adults, “<num_children>” and “<num_seniors> seniors Then I should see the child fare policy message And be on the ticket search page Examples: |origin |destination|num_adults|num_children|num_seniors| |Brussels|Chicago |0 |1 |0 | |Brussels|Chicago |0 |2 |0 | |Brussels|Chicago |0 |3 |0 | |Brussels|Chicago |0 |4 |0 | |Brussels|Chicago |0 |5 |0 | |Brussels|Capetown |0 |2 |0 | |Brussels|Capetown |0 |3 |0 | |Brussels|Capetown |0 |4 |0 | |Brussels|Capetown |0 |5 |0 |
- 34. Requirement Conversation Discovery Specification Automation For all, in a common language Behat
- 35. Links! Reading dannorth.net/introducing-bdd dannorth.net/2010/08/30/introducing-deliberate-discovery specificationbyexample.com/key_ideas.html “Domain Driven Design” Eric Evans (domainlanguage.com) lizkeogh.com/2010/02/02/theyre-not-user-stories Playing behat.org drupal.org/project/drupalextension code.google.com/p/selenium/wiki/PageObjects github.com/orangedigital/business-selector-extension github.com/BossaConsulting/phpspec2-expect