Test-Driven Development and Code Coverage

1. Test-Driven Development and Code Coverage

2. An Evening of Robert Burns Poetry Readings by Craig Murphy

3. Session Overview • “The simplest thing that could possibly work” • This session will provide an explanation and demonstration of: • How test-driven development (TDD) works • How code-coverage works • How to merge TDD and code coverage • A selection of tools that can help us work with TDD and code coverage • Code examples will be in C# using Visual Studio 2005 • Roman numeral conversion and a simple calculator • Not “text-book” examples – they tend to be “hard going” • I have a lot to cover, so this should be a fast-paced session • I may leave you to browse the Resources slides in your own time • I’m enthusiastic! Please tell me if I am going too fast! Test Driven Development and Code Coverage

4. Housekeeping Mobile ‘phones Fire Exits Toilets Automating the Build Process Using FinalBuilder 4

5. About Me XML XSLT XQuery XML Schema SOAP WML IntraWeb Web Services C# InterOp with Delphi RUP UML TDD in C#, VB.net and Delphi 8 Scrum • 50+ presentations delivered: • NRW06, NRW07 • DeveloperDeveloperDeveloper (UK Community Events) • Scottish Developers • Agile Scotland • British Computer Society (BCS) • UK Borland User Group (DDG) • Visual Basic User Group (VBUG) • VBUG .net Winter 2001 conference • XML One 2001 • 60+ articles published: • The Delphi Magazine • developers’ magazine (Dotnet Developers’ Group - DDG) • ASPToday.com (now Wiley, previously Wrox) • ASP.NET Pro, International Developer • CSharpCorner, DeveloperFusion Automating the Build Process Using FinalBuilder

6. Agenda • Motivation • The Tools • Test-Driven Development • Code Coverage • Summary • Resources Test Driven Development and Code Coverage

7. Motivation • There are times when we are too focused on application development • New/useful tools techniques are passed by • 60-90 minute sessions like these, personally, help me save time by: • Identifying new/useful tools and techniques • Demonstrating new/useful tools and techniques • Test-Driven Development (TDD) sits nicely in the eXtreme Programming (XP) “way of doing things” • TDD can be used without practicing XP • Search msdn.microsoft.com for TDD… • approximately 155,000 results Test Driven Development and Code Coverage

8. The Tools • NUnit 2.4.6 • Testing framework for .NET • Graphical front-end (clear “black/white” pass/fail indicator) • NCover 1.5.8 • “Do you know how much of your code is being tested” • Command-line • Creates an XML output file, XSL transformation for viewing • NCoverExplorer 1.4.0.7 • Graphical front-end for NCover • Windows application that uses NCover’s XML output file • TestDriven.NET 2.11.2177 • NUnit, NCover, NCoverage integration inside the Visual Studio IDE • Right-click context-sensitive menu • Free “liberal” personal edition; commercial Profession and Enterprise editions Test Driven Development and Code Coverage

9. Agenda • Motivation • The Tools • Test-Driven Development • Code Coverage • Summary • Resources Test Driven Development and Code Coverage

10. TDD – Agenda • What is TDD? • TDD Stages • TDD in C# • Demonstration • Why TDD? Test Driven Development and Code Coverage

11. What is TDD? • “Before you write code, think about what it will do. Write a test that will use the methods you haven’t even written yet.” • Extreme Programming Applied: Playing To Win • Ken Auer, Roy Miller • “The Purple Book” • A test is not something you “do”, it is something you “write” and run once, twice, three times, etc. • It is a piece of code • Testing is therefore “automated” • Repeatedly executed, even after small changes • “TDD is risk averse programming, investing work in the near term to avoid failures later on” • Munjal Budhabhatti, The Architecture Journal 14 Test Driven Development and Code Coverage

12. What is TDD? • TDD is a technique whereby you write your test cases before you write any implementation code • Forces developers to think in terms of implementer and user • Tests drive or dictate the code that is developed • “Do the simplest thing that could possibly work” • Developers have less choice in what they write • An indication of “intent” • Tests provide a specification of “what” a piece of code actually does – it goes some way to defining an interface • Some might argue that “tests are part of the documentation” • Could your customers/clients write tests? Test Driven Development and Code Coverage

13. TDD - Agenda • What is TDD? • TDD Stages • TDD in C# • Demonstration • Why TDD? Test Driven Development and Code Coverage

14. TDD Stages • In Extreme Programming Explored (The Green Book), Bill Wake describes the test / code cycle: • Write a single test • Compile it. It shouldn’t compile because you’ve not written the implementation code • Implement just enough code to get the test to compile • Run the test and see it fail • Implement just enough code to get the test to pass • Run the test and see it pass • Refactor for clarity and “once and only once” • Repeat Test Driven Development and Code Coverage

15. TDD Stages Write a test Refactor code(and test) Compile Run test, watch it pass Fix compile errors Write code Run test,watch it fail Test Driven Development and Code Coverage

16. Smells • During TDD, particularly the refactoring step, consider these smells: • Duplication • Once And Once Only (OAOO) • Setup / TearDown (NUnit attributes) • Some duplicated code reveals itself as common ‘initialisation’ code • And / Or as ‘cleanup’ code Test Driven Development and Code Coverage

17. TDD in C#, Visual Basic.net, Delphi 2005/6 • NUnit, csUnit, MbUnit • Are three xUnit implementations for .net languages • “MbUnit has been referred to as “unit testing on crack” [Hanselman] • xUnit is a colloquial umbrella term • Platform-specific and language-specific implementations • e.g. sUnit, JUnit, XMLUnit • Richard Fennell spoke about TSQLUnit at SQLBits, October 2007 • NUnit, csUnit and MbUnit • Provides an attribute-based testing framework • Attributes “instrument” code, adding meaning and intent • Makes use of Assert statements • Tests are written using Assertions • Actual and Expected results need to be known… Test Driven Development and Code Coverage

18. TDD in C# using NUnit Assert.AreEquals( expected, actual, msg ); [C#] [TestFixture] public class TestRoman1 { [Test] public void Roman1() { ClsRoman rc = new ClsRoman(); Assert.AreEqual("I",rc.toRoman(1),"1 fails to convert"); } } Test Driven Development and Code Coverage

19. Test-driven development using C# and NUnit demo Test Driven Development and Code Coverage

20. Test Complexity • Do the simplest thing • Dave Astels: “Strive for simplicity” • Write a test that fails (red) • Make the test pass (green) • Refactor implementation code (change/improve the internal design) • Use the compiler – let it tell you about errors and omissions • Today, compiler time is cheap • One assertion (Assert) per test • Has been the subject of furious debate on Yahoo’s TDD group Test Driven Development and Code Coverage

21. Small Steps Are Good • TDD promotes “small steps”, and lots of them • Small steps: the shortest distance between two points • Your destination is closer… • Red route • incurs “scrap and re-work” • Takes longer • May not cleanly reach its destination B A Test Driven Development and Code Coverage

22. Test Case Generation • Automate using tools • e.g. Kellerman Software’s NUnit Test Generator • http://www.kellermansoftware.com • Works with Visual Studio 2002 upwards…

23. Agenda • Motivation • The Tools • Test-Driven Development • Code Coverage • Summary • Resources Test Driven Development and Code Coverage

24. Code Coverage – Agenda • What is Code Coverage? • Demonstration • Code Coverage • Integrating Unit Tests and Code Coverage • Why Code Coverage? Test Driven Development and Code Coverage

25. What is Code Coverage? • Code Coverage is an approach or technique that sees you executing [all] the statements and paths through your code-base • In Code Complete 2, McConnell refers to code coverage and logic coverage as one and the same • e.g. Ensure that the all the paths through code are evaluated • e.g. if (…) … else … conditions are evaluated • Without tools/automation, code coverage is a labour-intensive activity • Manually updating code coverage reports was a chore • It is important to know/define what we lessons we can learn from code coverage • e.g. code coverage cannot help us with multi-parameter APIs with large numbers of input parameters and large numbers of return values… • Unless there are implicit tests in place Test Driven Development and Code Coverage

26. Code Coverage using C#, NUnit, NCover and NCoverage demo Test Driven Development and Code Coverage

27. Agenda • Motivation • The Tools • Test-Driven Development • Code Coverage • Summary • Resources Test Driven Development and Code Coverage

28. Test-Driven DevelopmentSummary • TDD may appear to require more development time, however, in reality: • Developer-level feature creep is avoided, no “over-implementation” • Quality of client-facing features is exceptionally high • TDD does not replace traditional testing • It defines a proven way that ensures effective unit testing • Tests are working examples of how to invoke a piece of code • Essentially provides a working specification for the code • Ideally, no code should go into production unless it has associated tests • Catch bugs before they are shipped to your customer • Often referred to as “No code without tests” • Tests determine, or dictate, the code • The programmers should write the tests • The programmers can’t wait for somebody else to write tests • It’s all about early problem identification, early find, early fix, reduced cost Test Driven Development and Code Coverage

29. Code Coverage Summary • Identifies code that your tests missed • Thus, you should find bugs you may not otherwise have found, code coverage “gives you clues” • Identifies code that does not have a test case exercising it • TDD helps me with the low-level functionality, code coverage helps me test Windows-based user interfaces • Code coverage can be a useful metric, but it must be used with care • Determine whether high code coverage is a good thing • Simply “touching” every line of code might not be suitable • Do not be sucked into “writing quick tests” just to improve coverage • Brian Marick on code coverage tools: “…they are only helpful…to enhance thought, not replace it” Test Driven Development and Code Coverage

30. Resources (Books) test-driven development: A Practical Guide Dave Astels Prentice-Hall/Pearson Education, 2003 ISBN 0-13-101649-0 Review available on my web-site ______________________________________ Test-Driven Development: By Example Kent Beck Addison-Wesley, 2003 ISBN 0-321-14653-0 Test Driven Development and Code Coverage

31. Resources (Books) Refactoring: Improving the Design of Existing Code Martin Fowler Addison-Wesley, 1999 ISBN 0-201-48567-2 __________________________________ Test-Driven Development in Microsoft.NET James W. Newkirk; Alexei A. Vorontsov Microsoft Press, 2004 ISBN 0-7356-1948-4 xUnit.net & xUnit Test Pattern Test Driven Development and Code Coverage

32. Test-Driven DevelopmentResources (web-sites) • NUnit: http://www.nunit.org • Charlie Poole’s blog “It’s the tests” • http://nunit.com/blogs/ • http://www.testdriven.net • Jamie Cansdale’s Visual Studio integration • Personal (free), Professional ($), Enterprise ($) • CSUnit: http://www.csunit.org • Manfred Lange’s .net testing framework • http://groups.yahoo.com/group/csunit • MbUnit: http://www.mbunit.com • http://www.nxtgenug.net/Article.aspx?ArticleID=107 Test Driven Development and Code Coverage

33. Test-Driven DevelopmentResources (web-sites) • Lutz Roeder’s .NET Reflector: • http://www.aisto.com/roeder/dotnet • xUnit implementations: • http://www.xprogramming.com/software.htm • http://www.junit.org • http://www.vbunit.org • http://www.testdriven.com (Brian Marick’s site) • Clarke Ching on Roman Numeral conversion in Microsoft Excel: • http://www.clarkeching.com/2006/04/test_driven_dev.html • Ideal if you need to “sell TDD” to your manager! • Improving Application Quality Using Test-Driven Developmenthttp://www.methodsandtools.com/archive/archive.php?id=20 Test Driven Development and Code Coverage

34. Code CoverageResources (web-sites) • testdrivendevelopment group (Yahoo): • http://groups.yahoo.com/group/testdrivendevelopment • Ron Jeffries, Dave Astels, Kent Beck, etc. are regular contributors • NCover: http://www.ncover.org • Peter Waldschmidt’s command-line code coverage for .NET • NCoverExplorer: http://www.kiwidude.com/blog/2006/01/ncoverexplorer-debut.html • Grant Drake’s front-end for NCover • NCover Browser http://www.sliver.com/dotnet/NCoverBrowser/ • Jeff Key’s early front-end for NCover • No source code available… • http://www.testdriven.com (Brian Marick’s site) • http://www.testing.com/writings/coverage.pdf • http://en.wikipedia.org/wiki/Code_coverage Test Driven Development and Code Coverage

35. Contact Information Craig Murphy http://www.twitter.com/CAMURPHY Updated slides, notes and source code: http://www.CraigMurphy.com http://www.CraigMurphy.com/blog

36. Questions? RED GREEN REFACTOR Test Driven Development and Code Coverage