Unit tests & TDD
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A session I did at Rupin Academic Center. Part of modern software engineering course for bachelor degree in computer science.
![This is a unit test
[TestMethod]
public void CheckPassword_ValidUser_ReturnTrue()
{
bool result = CheckPassword(“user”, “pass”);
Assert.IsTrue(result);
}](https://image.slidesharecdn.com/01unittests-131120093957-phpapp02/85/Unit-tests-TDD-9-320.jpg)
![This is also a unit test
[Test]
public void CheckPassword_ValidUser_ReturnTrue()
{
bool result = CheckPassword(“user”, “pass”);
Assert.That(result, Is.True);
}](https://image.slidesharecdn.com/01unittests-131120093957-phpapp02/85/Unit-tests-TDD-10-320.jpg)
![Arrange Act Assert
Divide the unit test into three parts:
[Test]
public void test() throws Exception
{
// Arrange
int first = 1;
int second = 2;
Calculator calc = new Calculator();
// Act
int result = calc.Add(first, Second);
// Assert
Assert.AreEquals(3, result);
}](https://image.slidesharecdn.com/01unittests-131120093957-phpapp02/85/Unit-tests-TDD-12-320.jpg)
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Unit tests & TDD
- 1. Unit testing Dror Helper Senior consultant Tuesday, Novemeber 19, 2013
- 4. Bugs are discovered too late
- 5. The cost of bugs Where does it hurt? 100% The pain is here! This is too late… 9 8 7 60% 6 5 40% 4 3 20% 2 1 0% 0 Requirements Coding Integration % of Defects Introduced Testing Cost to Fix a Defect Support Thousand $s % defects created 80% 10
- 6. When writing unit tests Quick feedback Am I writing the code right? Am I’m writing the right thing? Dependency & API analysis Avoid stupid bugs
- 7. After writing a unit test Immune to regression Change your code without fear Enable Rapid changes In code documentation
- 8. What is a unit test? Test specific functionality Clear pass/fail criteria Good unit test runs in isolation
- 9. This is a unit test [TestMethod] public void CheckPassword_ValidUser_ReturnTrue() { bool result = CheckPassword(“user”, “pass”); Assert.IsTrue(result); }
- 10. This is also a unit test [Test] public void CheckPassword_ValidUser_ReturnTrue() { bool result = CheckPassword(“user”, “pass”); Assert.That(result, Is.True); }
- 11. Unit tests are written by developers
- 12. Arrange Act Assert Divide the unit test into three parts: [Test] public void test() throws Exception { // Arrange int first = 1; int second = 2; Calculator calc = new Calculator(); // Act int result = calc.Add(first, Second); // Assert Assert.AreEquals(3, result); }
- 13. Project structure It is crucial to have a consistent naming convention: For Project: <project under test>Tests or <project under test>.UnitTests <project under test>.IntegrationTests For files (Test case): <class under test>Tests Example: CalculatorTests Never have your test in the same project as your production code!
- 14. Test naming Test names should be descriptive and explicit. Test names should express a specific requirement I like to use: Method_Scenario_Expected a.k.a UnitOfWork_StateUnderTest_ExpectedBehavior Public void Sum_NegativeNumberAs1stParam_ExceptionThrown() Public void Sum_simpleValues_Calculated () Public void Parse_SingleToken_ReturnsEqualTokenValue () From: http://osherove.com/blog/2005/4/3/naming-standards-for-unit-tests.html
- 15. Test classification Unit tests should be: – Small – Atomic – Test a single functional unit – Isolated! Integration tests are used to test system wide functionality
- 16. The test pyramid Manual testing UI automation Integration tests Unit tests
- 17. The test pyramid Manual testing UI automation End to End flow tests Scenario tests Integration tests Unit tests
- 19. Tools of the trade Server Build Server Source Control Build Script Dev Machine Unit Testing Framework Code Coverage Test Runner Isolation Framework
- 20. Continuous Integration Server Build What’s new? Commit There you go Source Control We automatically got •Error reports & logs •New version installer •Help files •More… Build Agents
- 21. Team Foundation Server (TFS)
- 22. TeamCity
- 23. Development environment • Make it easy to write and run tests – Unit test framework – Test Runner – Isolation framework • Know where you stand – Code coverage
- 24. Unit test framework Simplify the process of unit testing Provide the following: Control flow (attributes) Signal success/failure (Assertions) http://en.wikipedia.org/wiki/List_of_unit_testing_frameworks
- 25. Assertions Throw exception when condition is false. Easy to find: Assert.X StringAssert.X CollectionAssert.X New Syntax (Nunit): Assert.That(x, Is.Equal(y));
- 26. Attributes Declare information about the test: • TestClass/TestFixture • TestMethod/Test • ExpectedException • Ignore • And more
- 27. Test Runners Visual Studio TestDrive.Net R# TestRunner CodeRush TestRunner
- 28. Code coverage
- 29. Test Driven Development a software development process that relies on the repetition of a very short development cycle
- 31. The complete flow Write new Test Run all tests Run Test (fail) Refactor Write code Run test (pass)
- 32. Unit tests != TDD • The purpose of a unit test is to test a unit of code in isolation • TDD is used to drive the design of an application. • used to express what application code should do before the application code is actually written.
- 33. Examples, demonstrations & fun A DAY IN THE LIFE OF A TDD'ER
- 34. A Day in the Life of a TDD'er • The tools we use • Writing some code • OK, who broke the Build?! • Too much spare time…
- 35. The Tools We Use(d) • • • • • • Unit testing – MSTest/NUnit Build automation – FinalBuilder Continuous Integration – TeamCity Integrated tools – R#, TestDriven.NET Isolation Framework – Isolator (surprise!) Build Bunny!
- 36. Writing Some Code We begin with a clean slate Write new test Run tests Refactor Run All tests Write code
- 37. Writing Some Code An exercise in futility… Write new test Run tests Refactor Run all tests Write code
- 38. Writing Some Code Now we get our hands dirty Write new Test Run tests Refactor Run all tests Write code
- 39. Writing Some Code Make sure everything’s fine… Write new Test Run tests Refactor Run all tests Write code
- 40. Writing Some Code … and make it perform/look better Write new test Run tests Refactor Run all tests Write code
- 41. Writing Some Code Lets take her out for another spin… Write new Test Run tests Refactor Run all tests Write code
- 42. Want to learn more Check out the bowling kata: http://www.objectmentor.com/resources/articles/xpepisode.htm More TDD problems: https://sites.google.com/site/tddproblems/all-problems-1
- 43. OK, Who Broke the Build? • Something went horribly wrong! – And it’s easy to find who to blame – But it’s easy to find out what happened • Why is this important? – The project heartbeat – Healthy build == easy to release
- 44. Too Much Spare Time The foosball table The build bunny The Shooting of The Zombies Helping children with computer skills • • • •
- 45. The unit tester bookshelf
- 46. Presenter contact details C: 972.50.7668543 e: [email protected] b: blog.drorhelper.com w: www.codevalue.net
Editor's Notes
- #12: Example: writing unit tests
- #15: Ask them – why is the test name so important?
- #17: Succeeding with Agile. Cohn, Mike
- #18: Succeeding with Agile. Cohn, Mike
- #21: The backbone of TDD (and development)Show how CI & script runner run the test suite – perhaps publish results to web
- #38: Should show:NUnit
- #41: Resharper