Alba + Razor

[joemcbride]

It appears that to be able to invoke an endpoint that returns a Razor view you have to manually tell Razor where the needed Assemblies are. Yes, I just threw up a little myself. The end user may need to manually add additional assemblies.

Maybe this is the start of #28 ?

Original problem/solution: aspnet/Hosting#954 (comment)

public class SystemTestBase
{
    protected Task<IScenarioResult> run(Action<Scenario> configuration, Action<SystemUnderTest> systemConfigure = null)
    {
        using (var system = SystemUnderTest.ForStartup<Startup>())
        {
            system.ConfigureRazor<Startup>();

            system.Environment.EnvironmentName = "Local";
            systemConfigure?.Invoke(system);
            return system.Scenario(configuration);
        }
    }
}

public static class SystemUnderTestExtensions
{
    public static void ConfigureRazor<T>(this SystemUnderTest system, params string[] additionalAssemblies)
    {
        system.ConfigureServices(c =>
        {
            c.Configure((RazorViewEngineOptions options) =>
            {
                var previous = options.CompilationCallback;
                options.CompilationCallback = (context) =>
                {
                    previous?.Invoke(context);
                    context.Compilation = context.Compilation.AddReferences(GetReferences<T>(additionalAssemblies));
                };
            });
        });
    }

    private static IEnumerable<MetadataReference> GetReferences<T>(IEnumerable<string> additionalAssemblies)
    {
        var assemblyNames = new List<string>
        {
            "mscorlib",
            "System.Dynamic.Runtime",
            "System.Private.CoreLib",
            "System.Runtime",
            "Microsoft.AspNetCore.Html.Abstractions",
            "Microsoft.AspNetCore.Razor"
        };

        var assembly = typeof(T).GetTypeInfo().Assembly;
        var assemblies = assembly.GetReferencedAssemblies().Select(x => MetadataReference.CreateFromFile(Assembly.Load(x).Location))
                .ToList();

            assemblies.AddRange(CreateReferences(additionalAssemblies.Concat(assemblyNames).ToArray()));

        return assemblies;
    }

    private static IEnumerable<PortableExecutableReference> CreateReferences(params string[] assemblies)
    {
        return assemblies.Select(x =>
        {
            try
            {
                return MetadataReference.CreateFromFile(Assembly.Load(new AssemblyName(x)).Location);
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
                return null;
            }
        }).Where(x => x != null);
    }
}