Add retries for Selenium tests

[craigfowler]

These tests fail sometimes for reasons outside my control. For example timeouts and lack of response from BrowserStack.

I'd like to use NUnit's retry feature to retry tests which fail, so that they aren't recorded as flaky.

[craigfowler]

Consider Meta Llama for doing this (from the makers of PostSharp). This could add the attribute globally without repeating it on every test.

Might not be worth it though.

[craigfowler]

This is an AI generated response about metalama:

---

Yes, Metalama (PostSharp's successor) can absolutely do this. It's designed for exactly this kind of use case — applying aspects globally across an assembly using a fabric. Here's how you'd do it.

Install the packages:

dotnet add package Metalama.Framework

First, define an aspect that introduces the [Retry] attribute:

using Metalama.Framework.Aspects;
using NUnit.Framework;

public class AddRetryAspect : MethodAspect
{
    public override void BuildAspect(IAspectBuilder<IMethod> builder)
    {
        builder.Advice.IntroduceAttribute(
            AttributeConstruction.Create<RetryAttribute>(3));
    }
}

Then use a fabric to apply it globally across the assembly. A fabric is a compile-time class that Metalama automatically discovers and executes — you don't need to decorate anything with it manually:

using Metalama.Framework.Fabrics;
using NUnit.Framework;

public class ApplyRetryFabric : ProjectFabric
{
    public override void AmendProject(IProjectAmender amender)
    {
        amender.SelectMany(p => p.Types.SelectMany(t => t.Methods))
               .Where(m => m.Attributes.Any(a => 
                   a.Type.Is(typeof(TestAttribute)) || 
                   a.Type.Is(typeof(TestCaseAttribute))))
               .Where(m => !m.Attributes.Any(a => 
                   a.Type.Is(typeof(RetryAttribute))))
               .AddAspect<AddRetryAspect>();
    }
}

Just drop these two classes anywhere in your test assembly and Metalama picks them up at build time. The fabric selects every method carrying [Test] or [TestCase] that doesn't already have [Retry], and applies the aspect to it.

A few things worth knowing about Metalama compared to PostSharp:

Licensing — Metalama has a free tier that covers straightforward scenarios like this one, so you may not need a paid licence at all depending on what else you're doing with it.

IDE support — Metalama has a Visual Studio extension that shows you a "diff" of what the aspect is doing to your code at design time, which makes it much easier to verify the aspect is behaving as expected without having to inspect IL.

Maturity — It's relatively young compared to PostSharp, so you may occasionally hit rough edges, but for a use case this focused it should be solid.

This is now my top recommendation over the Fody approach given that PostSharp is being retired and Metalama is its intended replacement with a more accessible free tier.