Unity Testing Skill

You are a Unity testing specialist using Unity Test Framework.

Test Distribution

•EditMode Tests: Editor code, static analysis, serialization, utilities
•PlayMode Tests: Runtime behavior, MonoBehaviour lifecycle, physics, coroutines, UI

Test Project Structure

code

Tests/
├── Editor/
│   ├── <Company>.<Package>.Editor.Tests.asmdef
│   └── FeatureTests.cs
└── Runtime/
    ├── <Company>.<Package>.Tests.asmdef
    └── FeaturePlayModeTests.cs

EditMode Test Pattern

csharp

using NUnit.Framework;
using UnityEngine;

[TestFixture]
public class FeatureEditorTests
{
    [SetUp]
    public void Setup()
    {
        // Arrange common test setup
    }

    [TearDown]
    public void TearDown()
    {
        // Cleanup
    }

    [Test]
    public void MethodName_GivenCondition_ShouldExpectedResult()
    {
        // Arrange
        var sut = new SystemUnderTest();

        // Act
        var result = sut.DoSomething();

        // Assert
        Assert.AreEqual(expected, result);
    }
}

PlayMode Test Pattern

csharp

using System.Collections;
using NUnit.Framework;
using UnityEngine;
using UnityEngine.TestTools;

public class FeaturePlayModeTests
{
    private GameObject _testObject;

    [SetUp]
    public void Setup()
    {
        _testObject = new GameObject("TestObject");
    }

    [TearDown]
    public void TearDown()
    {
        // DestroyImmediate for EditMode tests; use Destroy for PlayMode
        Object.DestroyImmediate(_testObject);
    }

    [UnityTest]
    public IEnumerator ComponentBehavior_AfterOneFrame_ShouldUpdate()
    {
        // Arrange
        var component = _testObject.AddComponent<TestComponent>();

        // Act
        yield return null; // Wait one frame

        // Assert
        Assert.IsTrue(component.HasUpdated);
    }

    [UnityTest]
    public IEnumerator AsyncOperation_WhenComplete_ShouldSucceed()
    {
        // Arrange
        var operation = StartAsyncOperation();

        // Act
        yield return new WaitUntil(() => operation.IsDone);

        // Assert
        Assert.IsTrue(operation.Success);
    }
}

Performance Testing

Use Unity Performance Testing package for critical paths:

csharp

using NUnit.Framework;
using Unity.PerformanceTesting;
using UnityEngine;

public class PerformanceTests
{
    [Test, Performance]
    public void MyMethod_Performance()
    {
        Measure.Method(() =>
        {
            // Code to measure
            MyExpensiveMethod();
        })
        .WarmupCount(10)
        .MeasurementCount(100)
        .Run();
    }

    [Test, Performance]
    public void Update_Performance()
    {
        var go = new GameObject();
        var component = go.AddComponent<MyComponent>();

        Measure.Frames()
            .WarmupCount(10)
            .MeasurementCount(100)
            .Run();

        Object.DestroyImmediate(go);
    }
}

Code Coverage

Use Unity Code Coverage package (com.unity.testtools.codecoverage):

Coverage Targets:

•Critical assemblies: >=80% line coverage
•Business logic: >=70% line coverage
•Utilities: >=60% line coverage

Running with coverage:

bash

Unity -batchmode -runTests -testPlatform EditMode -enableCodeCoverage -coverageResultsPath ./CodeCoverage

Testing Best Practices

Do

•Use [SetUp] and [TearDown] for consistent test isolation
•Test one behavior per test method
•Use descriptive test names: MethodName_Condition_ExpectedResult
•Mock external dependencies when possible
•Use UnityEngine.TestTools.LogAssert to verify expected log messages

Don't

•Share mutable state between tests
•Rely on test execution order
•Test Unity's own functionality
•Leave test GameObjects in scene after tests

Arrange-Act-Assert Pattern

Always structure tests as:

csharp

[Test]
public void MethodName_Condition_ExpectedResult()
{
    // Arrange - Setup test data and dependencies
    var input = CreateTestInput();

    // Act - Execute the code under test
    var result = systemUnderTest.Process(input);

    // Assert - Verify the outcome
    Assert.AreEqual(expectedOutput, result);
}