Type generation with nullability fails

[rijulg]

Brief explanation

Having multiple optional and required properties on a class results in unexpected nullability info in the generated types.
Issue on commit id: 27d7f9e

Minimal Example

The following dotnet module generated the corresponding types as shown

node node-api-dotnet-generator --assembly dotnet.dll --typedefs types.d.ts

// dotnet.dll
namespace ExampleSpace
{
  public class Model1
  {
    public DateTime requiredDate { get; set; }
    public string? optionalString { get; set; }
  }
  public class Model2
  {
    public DateTime requiredDate { get; set; }
    
    public DateTime? optionalDate { get; set; }
  }
  public class Model3
  {
    public DateTime requiredDate { get; set; }
    public string requiredString { get; set; }
    public string? optionalString { get; set; }
  }
}

// types.d.ts
declare module 'node-api-dotnet' {

	export namespace ExampleSpace {
		export class Model1 {
			constructor();

			requiredDate?: Date;

			optionalString?: string;
		}
	}

	export namespace ExampleSpace {
		export class Model2 {
			constructor();

			requiredDate: Date;

			optionalDate?: Date;
		}
	}

	export namespace ExampleSpace {
		export class Model3 {
			constructor();

			requiredDate: Date;

			requiredString: string;

			optionalString?: string;
		}
	}
}

Further Investigation

I have investigated the issue rather thoroughly and implemented the following reflection method to test where the issue is coming from

    static void MyReflect(Assembly assembly) {
        Console.WriteLine($"Reflecting Assembly: {assembly.FullName}");
        NullabilityInfoContext _nullability = new();
        foreach(Type type in assembly.GetTypes()) {
            Console.WriteLine($"{type}{{");
            foreach (PropertyInfo property in type.GetProperties()) {
                var nullability = _nullability.Create(property);
                Console.WriteLine($"\tname: {property.Name}");
                Console.WriteLine($"\ttype: {property.GetType()}");
                Console.WriteLine($"\tpropertyType: {property.PropertyType}");
                Console.WriteLine($"\treflectedType: {property.ReflectedType}");
                Console.WriteLine($"\t\tnullability: ");
                Console.WriteLine($"\t\tReadState: {nullability.ReadState}");
                Console.WriteLine($"\t\tWriteState: {nullability.WriteState}");
            }
            Console.WriteLine("}");
        }
    }

Within TypeDefinitionsGenerator.cs the assembly is loaded using an assemblyResolver; To pinpoint the issue I call MyReflect as following:

        Assembly assembly = loadContext.LoadFromAssemblyPath(assemblyPath);
        MyReflect(assembly);
        MyReflect(Assembly.LoadFrom(assemblyPath));

Which provides the following information (note the output has been cut down)

1. Calling assembly loaded by assemblyResolver

ExampleSpace.Model1{
        name: requiredDate
        type: System.Reflection.TypeLoading.Ecma.EcmaProperty
        propertyType: System.DateTime
        reflectedType: ExampleSpace.Model1
                nullability: 
                ReadState: Nullable
                WriteState: Nullable
        name: optionalString
        type: System.Reflection.TypeLoading.Ecma.EcmaProperty
        propertyType: System.String
        reflectedType: ExampleSpace.Model1
                nullability: 
                ReadState: Nullable
                WriteState: Nullable
}

2. Calling assembly loaded directly

ExampleSpace.Model1{
        name: requiredDate
        type: System.Reflection.RuntimePropertyInfo
        propertyType: System.DateTime
        reflectedType: ExampleSpace.Model1
                nullability: 
                ReadState: NotNull
                WriteState: NotNull
        name: optionalString
        type: System.Reflection.RuntimePropertyInfo
        propertyType: System.String
        reflectedType: ExampleSpace.Model1
                nullability: 
                ReadState: Nullable
                WriteState: Nullable
}

Hypothesis

Based on the observations I believe that the Ecma Module is messing with the nullability information somehow; I haven't worked with that so far so I am not sure what within that module may be causing the issue. If there are any ideas, then I will be happy to investigate and provide a fix if and when I get time in future.

[jasongin]

I'll investigate.

[jasongin]

Fixed in #158