WIP

[Bartleby2718]

@manfred-brands @mikkelbu I've been looking into #759 in the past couple of days, but I'm getting the following error message in tests:

CS0103 The name 'Assert.ThatAsync' does not exist in the current context
at line 24 and character 18 in file TestClass.cs | await ↓Assert.ThatAsync(() => GetResultAsync(), Is.EqualTo(42));

I suppose this is because I didn't restrict the Analyzer/CodeFix to NUnit 4+. Is it possible to do so? If not, should I consider this not startable yet?

I tried updating TestUtility.WrapMethodInClassNamespaceAndAddUsings() to add #if NUNIT4 like this, but I'm still getting the error:

    #pragma warning disable CS8019
    using System;
    using System.Threading.Tasks;
    using NUnit.Framework;
    #if NUNIT4
    using NUnit.Framework.Legacy;
    #else
    using ClassicAssert = NUnit.Framework.Assert;
    #endif
    
    #pragma warning restore CS8019
    
    
    namespace NUnit.Analyzers.Tests.Targets.TestCaseUsage
    {
        [TestFixture]
        public class TestClass
        {
    #if NUNIT4
    
            [Test]
            public async Task Test1()
            {
                await Assert.ThatAsync(() => GetResultAsync(), Is.EqualTo(42));
            }
    
            private static Task<int> GetResultAsync() => Task.FromResult(42);
    #endif
        }
    }

[manfred-brands]

I suppose this is because I didn't restrict the Analyzer/CodeFix to NUnit 4+.

Correct and yes this is possible.
Your analyzer needs to override the AnalyzAssertInvocation that has the Version nunitVersion parameter.
See UpdateStringFormatToInterpolatableStringAnalyzer for an example.
And then only continue if the user uses NUnit4: nunitVersion.Major > 4