xUnit.net ExtensibilityBrad WilsonJim Newkirk

Schedule

Assert Extensibility 9:00

Before/After Extensibility 9:45

Fact Extensibility 10:15

BREAK 10:45

Fixture Extensibility 11:00

Runner Extensibility 11:30

Putting it all Together 11:45

Assert Extensibility

Not Easy to Add New Asserts

Limitations of the platform & language

Provide core assertions with the framework

Keep “assert language” consistent

No differentiation between failure and exceptions

Customization of Comparisons

IEquatable / IEqualityComparer Assert.Contains

Assert.Equal

IComparable / IComparer Assert.InRange

Fallback for Contains & Equal

Asserts that Return Values

When type is tested Assert.IsAssignableFrom

Assert.IsType

Assert.Throws

When collections are tested Assert.Single

Exception catcher Record.Exception

ExampleCompare dates without times

ExerciseFinish by 9:45

Before/After Extensibility

Design

Cross-cutting concerns Reusable attribute

Initializing environment

Cleaning up after stateful tests

Runs regardless of test outcome

Has no access to test class or method

Unspecified order (compose for guarantee)

ExampleRollback database

Brainstorming ExerciseFinish by 10:15

Fact Extensibility

Design

Answers: “What is a test method?” Enumeration of tests

Execution of tests

Metadata (skip, timeout, display name)

Why?

Metadata changes “I want all my tests to have a timeout”

“I want the display name of my test to be something other than method name”

Enumeration changes “I want this test method to be run many times, perhaps with

different input values for each run”

Execution changes “I want to do something different than just running the

method with no parameters”

Example[Theory] attribute

ExerciseFollowed by break, back by 11:00

Fixture Extensibility

IUseFixture

Share reusable fixture setup and teardown Constructor

Dispose

Most frameworks encourage base classes here Lack of multiple inheritance in the CLR

“Inherit to be reused, not to reuse”

ExampleTest data seed & cleanup

ITestClassCommand and RunWith

Answers: “What is a test class?” Pre- and post-fixture behavior

Pre- and post-test behavior

Test class creation & cleanup

Test method discovery

Test method ordering

ExampleRemove Randomization

ExerciseFinish by 11:30

Runner Extensibility

Design

Version resilient runner APIs

Link against xunit.runner.utility.dll, not xunit.dll

Test assembly lives in a separate app domain Assembly

Configuration File

(Optional) Shadow Copy

Low-Level API

Exector (remote)

ExecutorWrapper (local)

On the wire, it’s: XML as a string (for status)

Boolean continue flag (to cancel)

Don’t use this.

High-Performance API

Thin wrapper on top of ExecutorWrapper TestRunner

TestRunnerResult

IRunnerLogger

Cracks the XML into simple values

Not stateful; callback is mandatory

Runners: MSBuild, TD.NET, Resharper

Object-Oriented API

Object model on top of ExecutorWrapper MultiAssemblyTestEnvironment

TestAssembly, TestClass, TestMethod

TestStatus

ITestMethodRunnerCallback

Cracks the XML into objects

Stateful; callback is optional

Runners: Console, GUI

Project files (.xunit)

One or more assemblies

Output types & locations

Filters

Examplexunit.console

Putting it all Together

ExampleBDD with [Observation]

ExampleBDD with SubSpec

ExampleAmalga Best Practice Analyzer

Exercise

Thank You!http://xunit.codeplex.com/

@bradwilson @jamesnewkirk @xunit