Using LazyInject in UnitTests

[FireDragonGameStudio]

Hi, is it possible to use LazyInject within UnitTests? I tried something like the following and _foo in class Bar (line 13) is always null when executing the UnitTest. I already played around with the order of binding and couldn't solve this.

Best regards :)

using System;
using System.Threading.Tasks;
using Zenject;

public class Bar : BarBase, IBar {
    LazyInject<Foo> _foo;

    public Bar(LazyInject<Foo> foo) {
        _foo = foo;
    }

    public async Task<bool> Run() {
        return await _foo.Value.Run();
    }

    public void Register(Action<bool> callback) {
        int a = 5 + 2;
        callback.Invoke(true);
    }
}

public class BarBase {
    public BarBase() { }
}

using System;
using System.Threading.Tasks;

public interface IBar {
    Task<bool> Run();
    void Register(Action<bool> callback);
}

using System.Threading.Tasks;

public class Foo : IFoo {
    public async Task<bool> Run() {
        await Task.Delay(1000);
        return true;
    }
}

using System.Threading.Tasks;

public interface IFoo {
    Task<bool> Run();
}

using Moq;
using NUnit.Framework;
using System;
using Zenject;

[TestFixture]
public class FooBarUnitTest : ZenjectUnitTestFixture {

    [Inject]
    IBar _bar;
    [Inject]
    IFoo _foo;

    [SetUp]
    public void CommonInstall() {

        Container.Bind<IFoo>().To<Foo>().AsSingle();

        Mock<IBar> bar = new Mock<Bar>(_foo).As<IBar>();
        bar.CallBase = true;
        bar.Setup(b => b.Register(It.IsAny<Action<bool>>()))
            .Callback<Action<bool>>(async (action) => {
                action.Invoke(await bar.Object.Run());
            }
        );

        Container.BindInstance(bar.Object).AsSingle();
        Container.Inject(this);
    }

    [Test]
    public void TestInitialValues() {
        bool wasRunning = _bar.Run().GetAwaiter().GetResult();

        Assert.True(wasRunning);
    }
}

[svermeulen]

It looks like you are using moq to create the instance of Bar? You need to use zenject for this. If you create it through zenject then it should inject LazyInject parameters properly

[FireDragonGameStudio]

Thx for your swift reply an suggestion. I'll try it asap and close this issue afterwards :)

[FireDragonGameStudio]

@svermeulen If I use Zenject without moq, the object graph can't be created and the test fails. It either takes forever to fail (maybe some kind of loop) or fails with the error ZenjectException: Unable to resolve 'Foo' while building object with type 'Bar'.

[svermeulen]

Can you post your entire test?

[FireDragonGameStudio]

sure :)

using NUnit.Framework;
using Zenject;

[TestFixture]
public class FooBarUnitTest : ZenjectUnitTestFixture {

    [Inject]
    IBar _bar;

    [SetUp]
    public void CommonInstall() {
        Container.Bind<IFoo>().To<Foo>().AsSingle();
        Container.Bind<IBar>().To<Bar>().AsSingle();
        Container.Inject(this);
    }

    [Test]
    public void TestInitialValues() {
        bool wasRunning = _bar.Run().GetAwaiter().GetResult();

        Assert.True(wasRunning);
    }
}

[svermeulen]

The error message suggests that you need to bind Foo. In your code you are only binding IFoo

[FireDragonGameStudio]

When changing the binding to Foo (like Container.Bind<Foo>().AsSingle(); the test results in an endless loop and doesn't finish.

[svermeulen]

Is it waiting when you call GetResult? I'm guessing zenject has created IBar correctly and it's on to running your code

[FireDragonGameStudio]

Yes, but I'm just waiting for 1 second, before moving on. After calling await Task.Delay(1000); in class Foo it never returns.

[svermeulen]

I think it has something to do with your async code though, not zenject. Maybe check into what SynchronizationContext you're using, since that will determine how code is continued after an await

[FireDragonGameStudio]

Found the issue! The error is caused by Unitys old NUnit version (https://forum.unity.com/threads/async-await-in-unittests.513857/) The execution of async await in UnitTests is... different.

Thank you for pointing me into the right direction :) Correct test looks now like this:

using NUnit.Framework;
using System.Threading.Tasks;
using Zenject;

[TestFixture]
public class FooBarUnitTest : ZenjectUnitTestFixture {

    [Inject]
    IBar _bar;

    [SetUp]
    public void CommonInstall() {
        Container.Bind<Foo>().AsSingle();
        Container.Bind<IBar>().To<Bar>().AsSingle();
        Container.Inject(this);
    }

    [Test]
    public void TestInitialValues() {

        bool wasRunning = false;

        wasRunning = Task.Run(() => _bar.Run()).GetAwaiter().GetResult();

        Assert.True(wasRunning);
    }
}

Best regards :)