unity-testing

Unity Testing

Overview

The Unity Test Framework (NUnit 3 underneath) runs tests in two modes. EditMode tests run in the editor without entering Play mode — fast, ideal for plain C# rules, ScriptableObjects and editor tooling. PlayMode tests run the player loop — needed for scenes, physics, coroutines and input, and slower. Most tests should be EditMode tests against plain classes (testable-game-logic).

Core principle: EditMode first; PlayMode only for behaviour that needs the player loop. Read the result XML, not the log tail.

Which mode

Question	Mode	Typical setup
Does the damage/cooldown/inventory rule compute correctly?	EditMode	new the plain class
Is every shipped definition valid?	EditMode	AssetDatabase.FindAssets
Does a ScriptableObject-driven system behave?	EditMode	ScriptableObject.CreateInstance<T>()
Does the character land on the floor / trigger fire?	PlayMode	load a test scene, WaitForFixedUpdate
Does pressing Jump jump?	PlayMode	InputTestFixture
Does the coroutine/Awaitable sequence finish?	PlayMode	[UnityTest] yielding frames

Test assemblies

{
  "name": "Tests.EditMode",
  "references": ["Game.Core", "Game.Runtime", "UnityEngine.TestRunner", "UnityEditor.TestRunner"],
  "includePlatforms": ["Editor"],
  "overrideReferences": true,
  "precompiledReferences": ["nunit.framework.dll"],
  "defineConstraints": ["UNITY_INCLUDE_TESTS"],
  "autoReferenced": false
}

PlayMode assemblies leave includePlatforms empty (any platform) and drop UnityEditor.TestRunner unless they need editor APIs. Tests live where the repository keeps them (often Assets/Tests/EditMode and Assets/Tests/PlayMode); follow its naming — Method_Scenario_Expected when there is none.

EditMode examples

public class InventoryTests {
    [Test] public void Add_BeyondStackLimit_OverflowsToNewSlot() {
        var potion = ScriptableObject.CreateInstance<ItemDefinition>();
        potion.Configure(id: "potion", maxStack: 5);
        var inv = new Inventory(slots: 4);

        inv.Add(potion, 7);

        Assert.That(inv.Slots[0].Count, Is.EqualTo(5));
        Assert.That(inv.Slots[1].Count, Is.EqualTo(2));
        Object.DestroyImmediate(potion);
    }

    [TestCase(0f, 100)] [TestCase(0.5f, 50)] [TestCase(1f, 0)]
    public void Damage_ByArmorFraction_ReducesLinearly(float armor, int expected) =>
        Assert.That(DamageMath.Apply(100, armor), Is.EqualTo(expected));
}