Test Driven Development

Revision as of 22:48, 18 February 2016

Background:

Background reading

• 5 min TDD overview video https://www.youtube.com/watch?v=QCif_-r8eK4
• Graphical explanation of TDD http://www.agiledata.org/essays/tdd.html
• Kent Beck book (he invented TDD) http://www.amazon.com/exec/obidos/ASIN/0321146530/
• Astels TDD book http://www.amazon.com/exec/obidos/ASIN/0131016490/
• Unit test vs Acceptance test https://dzone.com/articles/Write-JUnit-Tests-in-Spring-With-Mocked-and-Real-Objects
• TDD in a CalPoly course https://users.csc.calpoly.edu/~djanzen/courses/405W10/presentations/TDD.pdf
• Research showing TDD's pro's and con's https://tuhat.halvi.helsinki.fi/portal/files/29553974/2014_01_swqd_author_version.pdf
• Is TDD Dead? https://www.youtube.com/watch?v=z9quxZsLcfo
• List of all open source testing tools - http://www.opensourcetesting.org/
• See appendix for more resources

Rationale

The method of how developers go about implementing code is varied. Test driven development is one such method stemming in the 2000's that has gained momentum as an accepted and research-proven method for increasing software quality, readability, and reliability. Testing software to assure that it works in certain within particular constraints is an extension of quality assurance (QA) efforts that most professional software products do to increase their products value. With TDD, this testing is built-in even before students to write their first line of code. This means that students will have a better grasp on what they are programming and why. It means that students will have code that not only works when they first implement it, but that will continue to work when others develop next to it and run the same tests.

Directions:

This activity follows a tutorial that steps you through the TDD development process in the Eclipse IDE using its integrated JUnit module. Follow the below tutorials, implementing the TDD test code in Eclipse on your own computer. Finally, you will create actual non-test code that gets the tests to succeed (green JUnit bar). You will hand in this code, the associated test, and two screenshots.

Setup Eclipse and JUnit

• Download and install Eclipse - JUnit comes with "Eclipse IDE for Java Developers"
• (Optional) For tips and gotchas on using JUnit in Eclipse, see the following:
  • http://www.codeaffine.com/2012/11/26/working-efficiently-with-junit-in-eclipse-2/

Next, follow the Eclipse-JUnit-based TDD tutorial located at:

• http://www.codeaffine.com/2014/08/12/junit-in-a-nutshell-hello-world/
  • It is an illustrated step-by-step walk through of creating a test and then creating the associated functional code.
• Implement the same test code and get a failing test, just like in the tutorial.
• You will be marked up for commenting your code.
• Take a screenshot of the failing test (red JUnit bar), alongside the test code used to show it.

You should now have a test case that fails, but the stub for the code.

• Now, you need to make the test succeed. This means implementing the main program code to make the test go green in Eclipse.
• You will be marked up for commenting your code.
• Take a screenshot of the succeeding test (green JUnit bar), alongside the code implemented to attain it.

Deliverables:

Code and screenshots:

• Test code and implementation code that, together, make a successful test case (green in Eclipse JUnit).
• A screenshot of the test failing (red JUnit bard), before you write the functional code.
• A screenshot of the test succeeding (green JUnit bar), along side the code you just ran.

Note: You may not use the screenshots provided in the tutorial, as that would be plagiarism. Provide full-screen shots that include the entire Eclipse work space.

Assessment:

Comments:

What should the instructor know before using this activity?

What are some likely difficulties that an instructor may encounter using this activity?

Additional Information:

Suggestions for Open Source Community:

Suggestions for an open source community member who is working in conjunction with the instructor.

This work is licensed under a Creative Commons Attribution 4.0 International License

Appendix

Examples of OSS projects that use TDD

Best examples

• http://junit.org/
  • Well-known java unit testing framework written by Kent Beck, inventor or TDD himself
  • https://github.com/junit-team/junit
  • https://github.com/junit-team/junit/tree/master/src/test
  • ex of actual test code: https://github.com/junit-team/junit/blob/master/src/test/java/junit/tests/framework/AssertTest.java

• https://github.com/unclebob/fitnesse
  • Written by one of the Agile Manifesto co-authors
  • Very clean code, tests in /test directory
  • Not as well known, but might be easier for students to understand

Weaker examples

• https://github.com/rails/rails
  • It is said that much of anything rails is developed via TDD
  • https://travis-ci.org/rails/rails
  • https://github.com/rails/rails/pull/23690

• http://www.sqlite.org/testing.html
  • Superb write up by SQLite of how they do extensive testing, but its possibly not developed with TDD principles, or maybe partially.

• https://github.com/AutoFixture/AutoFixture
  • Another TDD example project, but its around .NET .... meh
  • https://github.com/AutoFixture/AutoFixture/blob/master/Src/AutoFixture.xUnit.net.UnitTest/AutoDataAttributeTest.cs

TDD "Lessons"

• http://www.codeaffine.com/2014/08/12/junit-in-a-nutshell-hello-world/ , http://www.codeaffine.com/2012/11/26/working-efficiently-with-junit-in-eclipse-2/
  • A superbly written step-by-step walk through of creating a test and then creating the associated functional code
  • It uses JUnit, which is an open source technology - but it uses a helloworld example - not sure if we want this or more of an integration with an existing oss project
  • Code Affine gave us permission to use!

• https://schuchert.wikispaces.com/Cxx+TDD+Monopoly
  • Line-by-line explanation of code and tests and process to create Monopoly features via TDD
  • Not sure what students would do, as all answers are given
  • CC-BY-SA

• https://dzone.com/articles/Write-JUnit-Tests-in-Spring-With-Mocked-and-Real-Objects
  • Specific to spring framework, and not for beginners; possibly complex to implement for beginners
  • I think DZone is copyright encumbered :-/ all content on it is proprietary in their submission legal text

• http://technologyconversations.com/2013/12/20/test-driven-development-tdd-example-walkthrough/ http://osherove.com/tdd-kata-1/ https://vimeo.com/8506325
  • These are a great series of TDD "Practice Exercises"; It gives you requirements that you are supposed to serially step through and implement on top of each other
  • This uses open source, but it isn't involved in any existing oss project
  • Unknown copyright

• https://github.com/orfjackal/tdd-tetris-tutorial
  • Tetris based TDD
  • It gives you test cases, already written, and you code to satisfy the tests
  • License says "You may use and modify this material freely for personal non-commercial use. This material may NOT be used as course material without prior written agreement."

Ideas and research

TDD

• Idea 1: Find a project that already has a testing harness and associated tests; learn it, and add a new unit test
• Idea 2: Create a test harness to make, build, and run unit tests on an existing open source project
  • Jim Bowring has done this in the past, though it seems they are lengthy projects vs a shorter activity; Do we want to create a “project”-oriented LA?
• Idea 3: Use an existing JUnit exercise / tutorial to teach a simple TDD 'test first, code later' scenario

• Teach the “mental discipline” of testing
• How can we test a Requirement?
  • Ensuring testing starts at user requirement gathering
  • Iterating through tests once code has been written, helps to improve the tests

• Dave thinks ManageIQ does unit testing

• Background reading:
  • http://www.cs.cofc.edu/~bowring/ - course in testing
  • Boris Byser - the test guru
  • Kent Beck - extreme programming (ford motor)
  • http://foss2serve.org/index.php/Test_Coverage_Activity