Write your first test

Run the example tests, then write a Play Mode test with two players in a real ClientSim session and an Edit Mode test with a spy. You need the test assemblies from Add Udon Test Kit to your project.

Run the examples

1. Open Window > General > Test Runner.
2. In the PlayMode tab, select ExamplePlayModeTests and click Run Selected.

Unity enters Play Mode, ClientSim starts with a local player, the test spawns a second player, and the test passes.

If it fails before ClientSim starts, with a message naming project settings, run Tools > TsVRC > Udon Test Kit > Fix ClientSim Project Settings once and run the test again. See Fix the project settings ClientSim rejects.

Write a Play Mode test

In your Tests/PlayMode folder, create PlayerListTests.cs:

using System.Collections;
using NUnit.Framework;
using Tsvrc.UdonTestKit;
using UnityEngine.TestTools;
using VRC.SDKBase;

public class PlayerListTests : ClientSimTestBase
{
    [UnityTest]
    public IEnumerator RemovePlayer_AfterSpawning_LeavesOnlyTheLocalPlayer()
    {
        yield return Session.Start();
        VRCPlayerApi remote = Session.SpawnRemotePlayer("Remote");

        Session.RemovePlayer(remote);

        Assert.That(VRCPlayerApi.GetPlayerCount(), Is.EqualTo(1));
        Assert.That(ClientSimSession.FindPlayerByName("Remote"), Is.Null);
    }
}

ClientSimTestBase gives the test a Session and ends it after the test. Session.Start returns once the local player has joined, and SpawnRemotePlayer and RemovePlayer take effect before they return, so the test can assert straight away.

Run it from the PlayMode tab. It passes.

Write an Edit Mode test with a spy

UdonSharp code often calls other behaviours by method name, with SendCustomEvent. A spy records those calls. In your Tests/EditMode folder, create SpyTests.cs:

using NUnit.Framework;
using Tsvrc.UdonTestKit;

public class SpyTests
{
    [Test]
    public void SendCustomEvent_TwoSpies_RecordsBothInOrder()
    {
        using var calls = new CallLog();
        CallbackSpy first = calls.CreateSpy("First");
        CallbackSpy second = calls.CreateSpy("Second");

        second.SendCustomEvent(nameof(CallbackSpy.CallbackB));
        first.SendCustomEvent(nameof(CallbackSpy.CallbackA));

        Assert.That(calls, Is.EqualTo(new[] { "Second.CallbackB", "First.CallbackA" }));
    }
}

Here the test makes the calls itself. In a real test, you pass the spy to your own code as the behaviour it calls, and the log shows what your code called, in order. The using destroys both spies when the test ends.

Run it from the EditMode tab. It passes.

Where to go next

To test your own behaviours, add them to GameObjects in a Play Mode test, drive them, and assert on what they did. The how-to guides cover the usual next steps:

• Run tests in a scene of their own, including your world's scene.
• Test what happens for a player who isn't the owner.
• Check that saved data survives a rejoin.
• Check the calls your code makes by name.
• Run tests from the command line.