TDDTest Driven Development

What is TDD ?

Test Driven Development (First test programming) Is a software development process It’s actually an approach to design and develop testable code It’s base on short 5 step cycles

1-Start with writing unit tests. Unit tests are written based on Specs and Failure conditions (e.g. boundary conditions, potential exceptions, ...)

2-Run the unit tests and confirm that they fail 3-Then implement the actual methods to pass the tests 4-Run tests and confirm they pass 5-Refactor your code (Clean up the code, remove duplications …)

Why TDD?

Automated testing (saves a lot of time for assuring code’s health) Facilitates debugging (saves a lot of time in detecting problems) Protects the code from breaking changes Facilitates Continuous Integration (CI) and Delivery Improves the app design and quality of the code Forces developers to comply with SOLID design principles

Single Responsibility, Open-Closed, Liskov substitution, Interface Segregation, Dependency inversion

Types of Tests Unit test

A unit test is actually a class that tests another app component (another class) A unit test method Only tests a single unit of work (a method) There should be no dependency to Database, File, Network or any other I/O

resources whatsoever. Everything should happen in the memory So they should pass all the time, otherwise something’s wrong with code

Integration test It’s a class that tests combination of multiple units of work It’s OK to have dependencies to I/O resources So Configuration of dependencies (e.g. connection string) could result in test failure

Functional Test (a.k.a E2E test) Manual tests (QA’s Job) Automated E2E tests

Unit Testing

Unit test classes Unit Test Methods

3 main sections : Arrange Initialize values, fake dependencies Act Run the System under test (SUT), actually the Method under test Assert Check the return value or system status against expected values/criteria

Example

Arrange

ActAssert

Unit Test Tools

Tools for Running Tests and Asserting results Unit Test Frameworks :

Back-end (C#.net): MS Test, xUnit.net, NUnit, MbUnit, etc. Front-end (JS/AngularJS2): Jasmine, Chai, QUnit , etc.

Tools for faking dependencies Isolation Frameworks :

Back-end (C#.net): Moq, NSubstitute, MS Fakes (Moles), JustMock, TypeMock, Rhino Mocks

Front-end (JS): Jasmine, SinonJs

Back-end Unit Testing FrameworksFeature MS Test (v2) XUnit.net

(v2.x)NUnit (v3) MbUnit

DNX/.net Core Support YES YES YES but in next version’s RC

NO

Community No Open Source community

50 Contributors3 Active Devs1144 StarsPart of .NET Foundation

74 Contributors8 Active Devs763 Stars

WeakLatest update Oct 2014

VS Integration YES YES (Through plug-ins) YES (Through plug-ins) YES (Through plug-ins)

Supported by CI Tools TFS, VS Online, Team City, Jenkins

TeamCity, Jenkins, VS Online, TFS

TeamCity, Jenkins, VS Online, TFS

TFS

Parallel Execution Support YES (Per Test Class) – newly added

YES (Per Test Method) Yes (Per Test Class) NO

Extensible (Through Attribute Inheritance)

NO YES YES but limited and not documented yet

NO

Parameterized Test YES YES YES YES

Performance Supposed to be slower Faster (due to parallelism) Fast No comments found

Other • Not as active as the others and Slower in releasing new versions

• The most modern, Part of .NET Foundation

• More TDD adherence• 1 instance per test

method• Resharper integration• Prevents bad habits• .NET Core’s Default

• Widely used, currently de facto FW, Posted from Java

• Parameterized tests• 1 instance for all test

methods• Resharper integration• Well Documented

Seems to be dying!

The most popular frameworks in .NET landscape :

Types of Isolation Frameworks

Constrained Constrained to .net Compiler restrictions as they generate .net code and

compile it at runtime Can only mock public, non static members, no sealed classes

Unconstrained They use unmanaged APIs (Profiling APIs). They wrapped around the

running instance of CLR and are able to manipulate the way that managed code works

They can fake almost everything, private members, static members, and even 3rd party stuff

Back-end Isolation FrameworksMoq (4.x) NSubstitute MSFakes

(Moles) TypeMock FakeItEasy

Framework Type Constrained Constrained Unconstrained Unconstrained (Commercial)Constrained (Free)

Constrained

Needs profiling to be enabled

NO NO YES YES (Commercial)No (Free)

NO

Can fake 3rd Party systems

NO NO YES YES(Commercial)No (Free)

NO

.net Core Support YES YES YES Not Yet NO

Community 44 Contributors6 Active Contributors1460 Stars

31 Contributors5 Active Contributors696 Stars

Not Open source Not Open source 24 Contributor6 Active Contributors595

Notes • The most popular one

• More Readable

• Less readability

Only for 3rd Party Components99% of cases

Conclusion

Test runner/Framework for .net : XUnit.net .net Core Support, well adopted by community and being a part of .NET Foundation Forces testing best practices (through 1 instance per method approach) Good performance NUnit could be an option if we care about the abundance of resources

(Stackoverflow, blog articles, …) but XUnit.net is future proof Isolation Framework for .net : Moq (for 99% of cases), MSFakes (just for

mocking non-mockable 3rd party components) Moq is widely used, well documented and mature enough. MSFakes is the only free unconstrained FW among major players

Use FluentAssertions for better test readability

Final Points

For a real production code unit testing is a must, not just a choice What matters more than tools and frameworks we’re using, is writing

a well-designed testable code and being committed to testing. Watching Code Coverage and keeping it high Code and Test Review to prevent cutting corners and maintain the

test and code quality In the front-end we need to do unit testing as well. As it’s got UI logic

in it and exactly because of design and clean code concerns De facto libs for testing AngularJS apps are : Jasmine (Unit test FW) ,Karma (Test Runner), Protractor (code driven End-to-End automated test for AngularJS 2) runs on top of Selenium Webdriver