[BUG] Providing a Policy Name Selector which returns null causes an infinite loop

[kylejuliandev]

Observed behavior

If you use the OpenFeature Dependency Injection to setup a Policy, and you fail to specify a name in DefaultNameSelector function, the application will hang while infinitely trying to resolve IFeatureClient.

Expected Behavior

Specifying no name when configuring a DefaultNameSelector should resolve the default IFeatureClient.

Steps to reproduce

If you call AddOpenFeature and specify a Policy Name Selector which returns null, no IFeatureClient can be resolved from the dependency injection scope.

builder.Services.AddOpenFeature(featureBuilder =>
{
    featureBuilder
        .AddHostedFeatureLifecycle()
        .AddInMemoryProvider("InMemory", _ => new Dictionary<string, Flag>()
        {
            {
                "welcome-message", new Flag<bool>(
                    new Dictionary<string, bool> { { "show", true }, { "hide", false } }, "show")
            }
        })
        .AddPolicyName(policy =>
        {
            policy.DefaultNameSelector = provider =>
            {
                return null;
            };
        });
});

I suspect the issue is here:

dotnet-sdk/src/OpenFeature.DependencyInjection/OpenFeatureBuilderExtensions.cs

Lines 229 to 232 in 417f3fe

	if (name == null)
	{
	return provider.GetRequiredService<IFeatureClient>();
	}

If no name is configured, we attempt to resolve any IFeatureClients already registered. However, this just ends up calling itself.

[kylejuliandev]

Fix should be ported in to #531