xUnit.js (http://xunitjs.codeplex.com) is a host-agnostic javascript unit test framework that can be run directly from the command line on Linux, Mac, and Windows. Primarily file I/O-based, and requiring neither an HTTP server nor a browser, xUnit.js is a prime candidate for seamless inclusion in build automation systems, continuous integration environments, and even IDEs. xUnit.js encourages developers and quality engineers to follow common testing patterns such as Arrange-Act-Assert, Single-Assert, and Behavior-Naming; and development patterns such as Loose-Coupling, Inversion-Of-Control, Dependency-Injection, and Design-For-Testability. Join us to talk about how to write testable javascript, and how to exercise your javascript APIs and programs cleanly and consistently.

1. Javascript Unit Testing with xUnit.js
Building cleaner APIs, faster!
John Buchanan, salesforce.com, inc.
Lead Member of Technical Staff

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3. Challenges:
1. What are some of the problems with testing javascript?

4. Challenges:
1. What are some of the problems with testing javascript?
• Boundary Control (Web requests, DOM access)

5. Challenges:
1. What are some of the problems with testing javascript?
• Boundary Control (Web requests, DOM access)
• Automation / Continuous Integration

6. Challenges:
1. What are some of the problems with testing javascript?
• Boundary Control (Web requests, DOM access)
• Automation / Continuous Integration
• Design Dependencies, Encapsulation

7. Challenges:
2. What are the differences between unit and integration tests?

8. Challenges:
2. What are the differences between unit and integration tests?
• Single module or component vs. interactions between modules

9. Challenges:
2. What are the differences between unit and integration tests?
• Single module or component vs. interactions between modules
• Boundary Control (Web requests, DOM access)

10. Challenges:
2. What are the differences between unit and integration tests?
• Single module or component vs. interactions between modules
• Boundary Control (Web requests, DOM access)
• Cost to exercise in automation: Unit tests are cheap

11. Challenges:
2. What are the differences between unit and integration tests?
• Single module or component vs. interactions between modules
• Boundary Control (Web requests, DOM access)
• Cost to exercise in automation: Unit tests are cheap
• Dependencies are abstracted in units, included in integrations

12. xUnit.js

13. So what is
xUnit.js?

14. xUnit.js
A Host-Agnostic Test Engine with an
Attribution Based Console Runner

15. lolwut.

16. A brief history of
xUnit.js

17. xUnit.js:
• Started in 2006, open source project hosted on CodePlex
• Frustrated with typical test registration systems
• Environmental requirements were expensive (Server, browser)
• Loved the simplicity and speed of the WSH (cscript.exe)
• Starting to understand using unit tests as a design tool

18. Unit Tests:
• Should be easily organizable
• Must to be simple to add, minimizing “dev bounce”
• Need to be easy to run, but also run fast
• Should help enforce dependency isolation
• Could allow for custom types of decoration (Ignore, Test Category,
etc.)

19. Host Agnostic:
• Should support common hosts out of the box:
•Google Chrome (V8)
•Mozilla Firefox (SpiderMonkey)
•Microsoft Internet Explorer 4-11 (JScript and Chakra, via cscript.exe)
•Mozilla Rhino
• Must also be able to easily add new and special use hosts:
•JSDB
•NodeJS
•PhantomJS

20. Realization:
• We don’t need a web server
• We don’t even need a browser
• All we need is the engine, the test file, and the file under test.*
* Drastic simplification – wait for it… ☺

21. xUnit.js
A Host-Agnostic Test Engine with an
Attribution Based Console Runner

22. Missed Mandates:
•
•
Organizable:
• Let’s call tests “Facts”, to encourage single aspect-testing
• We’ll group Facts into “Fixtures”, based on “like behavior”
• E.g. several tests exercising a single method
Easy To
Add:
• Want to maintain registration with the test
• C# style attributes are a great [Example] of this behavior
• The syntax is valid javascript, and will be ignored!

23. Test
Code
[Fixture]
Source Code
function FooClass(){
function foo(){
this.foo=function(){
return “foo”;
};
[Fact]
function ReturnsFoo(){
var expected=“foo”;
}
var actual=new FooClass().foo();
Assert.Equal(expected, actual);
}
}

24. Successful Run:

25. Failures, Errors, Script Errors:
[Fixture]
function foo(){
[Fact]
function FailsEqualityAssertion(){
var expected=true;
var actual=false;
Assert.Equal(expected, actual);
}
}
Failure

26. Failures, Errors, Script Errors:

27. Failures, Errors, Script Errors:
[Fixture]
function foo(){
[Fact]
function ErrorsOnUnknownMember(){
var expected=true;
var actual={value:true}.slice(0,1);
Assert.Equal(expected, actual);
}
}
Error

28. Failures, Errors, Script Errors:

29. Failures, Errors, Script Errors:
[Fixture]
function foo(){
[Fact]
function ThrowsSyntaxErrorOnLoad(){
var expected=if(true));
var actual=false;
Assert.Equal(expected, actual);
}
}
Script Error

30. Failures, Errors, Script Errors:

31. Mocks and Stubs:
[Fact]
function MocksWindowReferenceOnHost(){
var expected="expected";
var mockWindow=Mocks.GetMock(Object.Global(), "window", expected);
var actual=null;
mockWindow(function(){
actual=window;
});
Assert.Equal(expected, actual);
}

32. Mocks and Stubs:
[Fact]
function ReturnsResultWindowHandle(){
var expected="expected";
var windowStub=Stubs.GetObject(
{open:{returnValue:expected}},
{location:"known/url"}
);
var actual=openResults(windowStub);
Assert.Equal(expected, actual);
}
function openResults(
targetWindow
){
var resultsWindow =
targetWindow.open(
"results/url"
);
return resultsWindow;
}

33. Data-Driven
Tests:Data(1,2,3,4)]
[Fact,
function VerifiesDataIsInRange(data){
var expectedLow = 1;
var expectedHigh = 3;
var actual=data;
Assert.InRange(actual,expectedLow,expectedHigh);
}

34. Usage:
[…]

35. Benefits of Use Driven Development:
• Lightweight code host improves development cycle
• No need to wait for browser to manually test most code
• Waste less time understanding emergent side effects
• Maintain confidence while refactoring
• Use unit tests to architect cleaner, more usable APIs
The Big One:

36. +
xUnit.js =

37. Challenges:
• Multiple build automation and CI systems
• OS interoperability requirements
• Large browser (javascript engine) support matrix
• Many different teams and modules, with different behaviors
• Existing tests required full system and browser automation
• Selenium tests were becoming increasingly slow and unwieldy

38. Solutions:
• xUnit.js integrates easily as a command line or processor task
• Out-of-box support for native file I/O strategies and host environments
• Pluggable design allows for simple override and customization patterns
• Custom output strategies allow for report and issue tracker integration
• Shell execution and boundary control obviate end-to-end setup needs
• Selenium tests can be retargeted as integration and smoke tests

39. Custom Enhancements:
• JSCover Support (http://tntim96.github.io/JSCover/)
• Automatic issue assignment based on changelist author
• Test health history report integration

40. +
xUnit.js =

41. Preparation:
• Determine your test matrix
• Build or acquire necessary host engines
• Identify your build system’s executable target structure
• Identify your target test directories and files

42. Integration:
• Create CI target, .bat file, or .sh script
cscript ./Tools/xUnit.js.Console.js ../../Tests
d8 – ./Tools/xUnit.js.Console.js -- ../../Tests
js ./Tools/xUnit.js.Console.js ../../Tests
• Customize your installation (Optional)
•Attributes (Default file import locations, etc.)
•Output strategies (Reporting, Custom xml formats)
• Integrate additional tools (Optional, but highly recommended)
•JSCover (http://tntim96.github.io/JSCover/)

43. Happy Coding!

44. xUnit.js
http://xunitjs.codeplex.com/
John Buchanan
LMTS, salesforce.com, inc.