Turn this into MemberData where you yield the MethodInfo.
```C#
public static IEnumerable<object[]> NonActionAttributeData
{
    get
    {
        return typeof(Controller).GetTypeInfo()
                                 .DeclaredMethods
                                 .Select(method => new [] { method });
    }
}


public void NonActionAttribute_IsOnEveryPublicMethodFromController(MethodInfo method)
 {
     Assert.True(method.IsDefined(typeof(NonActionAttribute)));
 }
```

This way the test failure would say what method doesn't have the attribute as part of the failure.