Unit Testing and

Test-Driven Development

In Unity3D

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Definitions

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Test“Automated code that

invokes a system and checks behaviour.”

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Unit Test“Checks a single

assumption about the behavior of one system.”

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Integration Test

“Checks multiple systems are correctly connected”

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Unit Test != Integration Test

Only fails when target assumption fails

Fails when one of multiple implicit assumptions fail

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Qualities of a Unit Test

Readable

Maintainable Trustworthy

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[Test] void UpdatePath_OneActionChild_AddsSelAndChildToPath() { var actionNode = FakeAction.CreateStub(); m_selNode.AddChild(actionNode);

m_selNode.UpdatePath(m_path, NodeResult.Fails, null);

var desiredPath = new ITreeNode[] { m_selNode, actionNode }; Assert.IsEqualSequence(m_path, desiredPath); }

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Test Driven Development

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SCIENCE!•15-30% higher code “quality”•10-20% longer development time

http://biblio.gdinwiddie.com/biblio/StudiesOfTestDrivenDevelopmentThursday, 22 August 13

TDD1: Write a unit test2: Watch it fail3: Make it pass simply4: Refactor5: Goto 1

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Demo

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TDD and Unity3D

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NON-TRIVALNo post-

compile hook

MonoBehaviours are un-unit-testable

Maintainable

Lots of alt-tabbing

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Model View Controller

Maintainable

MonoBehaviour View

Game code Controller

Struct data Model

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class InitialGunSetupView : MonoBehaviour

Model View Controller

Maintainable

class Gun : MonoBehaviour

class GunController

class AmmoView : MonoBehaviour

struct GunModelTDD

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Model View Controller

Maintainable

class Gun : MonoBehaviour { public GunModel Model { get; private set; }

void Awake() { Model = new GunModel(); m_controller = new GunController(Model); class AmmoView : MonoBehaviour { void Awake() { m_model = GetComponent<Gun>().GunModel;

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Dependency Injection

public void GunController(GunModel model, IWorldPhysics physics) { Physics = physics; Model = model;}

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Recap

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•Unit tests test only one thing•Readable, maintainable, trustable•SCIENCE says TDD is e!ective•Write test, see fail, make pass, refactor•Model-View-Controller and Dependency Injection make TDD possible in Unity

•Kent Beck, “Test Driven Development”•Roy Osherove, “Art of Unit Testing”•UnTest http://www.github.com/tenpn/untest•Moq https://www.nuget.org/packages/moq•StrangeIOC http://thirdmotion.github.io/strangeioc/

Andrew Fray, @tenpn, andrew.fray@gmail.com http://andrewfray.wordpress.com

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