Finding a call inside a async method does not work (sometimes)

[Urganot]

Hi,

I currently struggle with a really weird issue. What I am trying to do is to write a test that makes sure that DateTime.Now is never used. My code works most of the time. I observed that if a method uses the async keyword, the test will not find a call to DateTime.Now

This is my test code:

private static readonly Architecture architecture =
        new ArchLoader().LoadAssemblies(typeof(Startup).Assembly,
                                        typeof(DateTime).Assembly,
                                        typeof(GuidelineTests).Assembly)
                        .Build();

    [Fact]
    public void NameSpace_UsageCheck_NoDateTimeNowForGettingTimestamps()
    {
        var dateTimeNowGetMethodName = typeof(DateTime).GetProperty(nameof(DateTime.Now))?.GetGetMethod()?.Name;
        dateTimeNowGetMethodName.Should().NotBeNull();

        var methods = MethodMembers()
                     .That()
                     .AreDeclaredIn(typeof(DateTime))
                     .And()
                     .HaveFullNameContaining(dateTimeNowGetMethodName);

        var types = Types().That().DoNotResideInNamespace(typeof(DateTime).Namespace).And().DoNotHaveFullName(typeof(GuidelineTests).FullName);

        var method = MethodMembers().That().HaveNameContaining("InsertAsync_ConnectionInformationPersisted3").GetObjects(architecture).ToList();
        
        var rule = MethodMembers()
                  .That()
                  .AreDeclaredIn(types)
                  .Should()
                  .NotCallAny(methods);

        rule.Check(architecture);
    }

The weird thing now is that when I tried to replicate this behaviour in a new project, it suddenly works as I expect it.
You can find the test project here: https://github.com/Urganot/ArchUnitAsyncIssue
Unfortunately I am unable to share code from the original project.

If I run my tests in the demo project, all usages of DateTime.Now will be found. In my original project, only calls from non async methods are found.
To test this, I just changed the signature.

In my original project, this DateTime.Now will NOT be found.

    [Fact]
    public async Task Test1()
    {
        var timeStamp = DateTime.Now;
    }

But only changing the signature to

    [Fact]
    public void Test1()
    {
        var timeStamp = DateTime.Now;
    }

Makes it so that it IS found

Does anybody have any idea, what is happening here?

[alexanderlinne]

Hi @Urganot,

internally, the compiler transforms async methods into a state machine, so I would suspect that the issue stems from the specific structure of your method. Maybe you could inspect the IL generated by dotnet for your internal code and the IL of the example project and see if there are any differences in how your code is transformed? Did you make sure to run both projects in debug mode?

[Urganot]

God damn it...

The issue was that I was in Release mode... that cost me two hours yesterday. Thank you so much :)

To prevent this in the future, I added a check for this:

#if !DEBUG
        throw new Exception("Architecture tests should only be run in DEBUG mode!");
#endif

[alexanderlinne]

I'll put this on my list, maybe ArchUnitNET should print a warning when running in release mode or even fail when something is encountered that is known to not work.