Check the calls Udon code makes

When your code runs as Udon, through UdonHost, give it test doubles that run as Udon too, and have each double record the calls it gets in an UdonCallLog. For code that runs as plain C#, a CallbackSpy does this instead, as in Check the calls your code makes by name.

Write a double

Doubles that run as Udon go in the Tests/UdonDoubles folder that Test Assemblies creates, next to ExampleUdonDouble. Its assembly compiles into player builds, as the compile for upload needs.

In that folder, create the double with Assets > Create > U# Script, which also creates its program asset. Give it a field for the log and a method for each call your code makes, which adds the call to the log:

using Tsvrc.UdonTestKit;
using UdonSharp;

public class RoundListenerDouble : UdonSharpBehaviour
{
    public UdonCallLog Log;

    public void OnRoundEnded()
    {
        Log.Add(name + ".OnRoundEnded");
    }
}

UdonSharp compiles every U# script of a project together, so no other U# class can have the same namespace and name as the double.

Check the calls

In a test class that extends UdonTestBase, create the log, the double and the behaviour under test, connect them, act, and assert on what the log recorded:

UdonBehaviour log = Udon.Create<UdonCallLog>("Log");
UdonBehaviour listener = Udon.Create<RoundListenerDouble>("Listener");
listener.SetProgramVariable(nameof(RoundListenerDouble.Log), log);
UdonBehaviour referee = Udon.Create<RoundReferee>("Referee");
referee.SetProgramVariable(nameof(RoundReferee.Listener), listener);

referee.SendCustomEvent(nameof(RoundReferee.EndRound));

Assert.That(UdonHost.Calls(log), Is.EqualTo(new[] { "Listener.OnRoundEnded" }));

A field that holds an UdonSharpBehaviour takes the UdonBehaviour that Create returned. Doubles that share a log record into it in the order the calls arrive, so one assertion covers several doubles and the order between them.