Test Driven Development (TDD) is a technique where tests are written before code to validate functionality. It promotes writing small testable units through the "red-green-refactor" process of writing a failing test, passing code, and refactoring. Popular unit testing frameworks for .NET like MSTest, NUnit, and xUnit allow automating tests that are fast, independent, repeatable, self-validating, and timely. Mocking frameworks like Moq and FakeItEasy generate stubs and fakes to isolate dependencies during testing. TDD helps reduce bugs and technical debt when refactoring legacy codebases lacking tests.

1. Test Driven Development
Nur Zeynep Taşkın

2. What is Test Driven Development(TDD)?
 Test-Driven Development (TDD) is a technique for building software that
guides software development by writing tests
 Write test first,then write out logic
 «Code without tests is bad code» Michael C. Feathers
 How can you have a test if there is nothing to test?

3. Test Driven Development (TDD) Basics

4. Unit Testing Basics
Production CodeUnit Tests Integration Tests

5. Effective Unit Tests Are F.I.R.S.T
Fast
to run them
frequently
Independent
of each other
Repeatable
in any
environment
Self-Validating
and so either
passing or failing
Timely
written before the
production code

6. Advantages Of Unit Testing

7. Popular Unit Testing Frameworks for .NET
MSTest
Comes with Visual Studio
https://github.com/Micro
soft/testfx
NUnit
Initially ported from JUnit
Current production
release, version 3, has
been completely rewritten
https://github.com/nunit/
nunit
xUnit
Written by the original
invertor of NUnit v2
https://xunit.github.io/

8. Demo 1
 Requirement:
“Create a library method that takes in a
sentence and a single character as
parameters. The method should return a
number that indicates how many times
the character appears in the sentence.”

9. What is Mocking?
 Mock Objects
 Fake
 Stub
 Mock
 Popular mocking frameworks for .Net:
 Moq
 Nsubstitute
 NMock3
 Rhino Mocks
 FakeItEasy
 JustMock

10. Microsoft Fakes
 Fakes come in two flavors:
 Stub
 Shim

11. Demo 2

12. TDD and Legacy Code
 Legacy code is
 «Code without tests»
 «Code you're afraid to change»
 TDD is difficult to use on legacy codebases
 The first step is admitting you have a problem

13. Code Coverage
 If you've been following TDD, then there is no code that was ever written
without being required by a test, so you should always be near 100%
coverage.
 Visual Studio Code Coverage Tool:

14. Visual Studio Code Coverage
 ExcludeFromCodeCoverage

15. Other Test Types
 Integration Tests
 User Interface Tests
 Performance and Stress Tests
 Security Tests
 User Acceptance Tests