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Acceptance Test Driven Development with SpecFlow and Friends

Acceptance Test Driven Development with SpecFlow and Friends. Christopher Bartling Joel Levandoski. Contact information. Christopher Bartling chris.bartling@gmail.com Twitter: @cbartling Joel Levandoski joel.levandoski@gmail.com Twitter: @joellevandoski. Topics.

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Acceptance Test Driven Development with SpecFlow and Friends

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  1. Acceptance Test Driven Development with SpecFlow and Friends • Christopher Bartling • Joel Levandoski

  2. Contact information • Christopher Bartling • chris.bartling@gmail.com • Twitter: @cbartling • Joel Levandoski • joel.levandoski@gmail.com • Twitter: @joellevandoski

  3. Topics • Acceptance Test Driven Development (ATDD) • SpecFlow for .NET • Behavior Driven Development (BDD) tool • WatiN and WebAii • Live demonstration • Questions

  4. Acceptance Test Driven Development • ATDD • Acceptance tests are executable specifications of desired behavior and functionality of the system • Expressed in language of the problem domain • Automated • Regression suite • Development is driven from the outside-in

  5. ATDD vs. TDD • TDD is extremely valuable, but you need more • Achieve great unit test coverage and still not deliver valueto the customer • ATDD focuses on complete features and functionality • ATDD: macro view • TDD: micro view

  6. SpecFlow for .NET • BDD testing framework • Integrates nicely with Visual Studio • Acceptance tests manifest themselves as features and scenarios • SpecFlow generates automated test from features • SpecFlow tests run as normal xUnit tests • Visual Studio test runner, build server

  7. Features • Describe some piece of functionality of the system • Maintained in a .feature file • Plain readable text • Understandable by all parties, including business • Gherkin format, popularized by Cucumber • Features contain one or more scenarios

  8. Feature file example Feature: Calculate Net Present Value In order analyze the profitability of a project As a project manager I want to be able to calculate the project’s Net Present Value Scenario: A project is rejected Given a project to evaluate When data is entered reflecting a failing project ROI scenario Then the net present value calculator will reject the project

  9. Scenarios • A scenario describes a single acceptance test for a feature • Most features are composed of multiple scenarios • SpecFlow generates a test for each scenario • The name of the test is generated from the scenario title

  10. Scenario example Scenario: A project is rejected when its NPV is negative Given a project to evaluate When data is entered reflecting a failing ROI scenario Then the net present value calculator willreject the project

  11. Scenario steps • Used to compose a scenario • Custom code to automate your application • Describe preconditions, triggering action, and verification of outputs for the acceptance test • Given: preconditions • When: triggering action • Then: behavior and state verifications

  12. Scenario step example Givena project to evaluate is matched to the following step definition binding… [Given(@"a project to evaluate")] public void GivenAProjectToEvaluate() { . . . }

  13. Set up and tear down • Attributes for before and after events • TestRun • Feature • Scenario, ScenarioBlock • Step • Specificity achieved when used with tags

  14. Tags • Markers that can be applied to features and scenarios • Useful for selectively mixing in behavior • Used to categorize scenarios • Some unit test frameworks support this categorization tagging • Custom tags you define

  15. Tag example @WatiN Scenario: Save valid sample size mid range Giventhe user enters 10 as sample size Whenthe user selects save Thenthe value is stored

  16. Tag example used with BeforeScenario [BeforeScenario("WatiN”)] public void BeforeScenarioUsingWatiN() { ... }

  17. Background • Common preconditions for all scenarios in a feature • Contains one or more scenario steps • Executed before any other steps in the scenario • SpecFlow generates a method from the background element in the feature file in the test class • Invoked from each scenario test case in the test class

  18. Background example Background: Given that the welcome page is displayed Scenario: Add a comment to a book being reviewed . . .

  19. Scenario outlines • Data-driven scenarios or scenario templates • Consists of • Scenario template specification with data placeholders • Set of examples providing values for placeholders • SpecFlow generates parameterized test logic for the scenario outline and individual test method for each example set

  20. Scenario outline example Scenario Outline: Score calculation tables Given a new bowling game When I roll the following series: <rolls> Then my total score should be <total score> Examples: | game | rolls | total score | | beginners game | 2,7,3,4,1,1,5,1,1,1,1,1,1,1,1,1,1,1,5,1 | 40 | | one single spare | 2,8,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 | 29 |

  21. ScenarioContext • ScenarioContext.Current.Pending() • Causes the step definition to return pending • Used to signal a stubbed step definition • ScenarioContext.Currentdictionary • Allows you to carry context/state across step definitions participating in scenario

  22. WatiN • Open source browser automation tool for IE and Firefox • Similar to Selenium, WebDriver, Watir • Browser abstraction • Find elements using CSS selectors • Interact with AJAX web elements • Handle popup dialogs (native and HTML)

  23. WebAii • Browser automation tool from Telerik • Automates both web 2.0 and Silverlight applications • HTML element wrappers • WaitForElement(s) support when using AJAX • Identifying elements using LINQ • Invoke JavaScript directly from test code

  24. Best practices • Write high-level specifications • Specifications should remain stable over time • Build a scripting interface for manipulating your system under test (SUT) • Focus specifications on isolated behaviors • Think of specifications in Given-When-Then format • Use the Page Object pattern

  25. Smells • Specifications are constantly changing • Specifications are composed of “sequential command executions” • Specifications have a lot of instrumentation or fixture code • Specification examples exhibit same structure

  26. Net Present Value Calculator Demo • Used in capital budgeting • Measures the excess or shortfall of cash flows, in present value terms, once financing terms have been covered • Demo has two implementations • ASP.NET MVC • Silverlight

  27. Questions?

  28. Literature cited • http://www.concordion.org/Technique.html • http://www.telerik.com/automated-testing-tools/webaii-framework-features.aspx • http://watin.org/ • http://www.specflow.org/ • http://code.google.com/p/selenium/wiki/PageObjects

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