InterfaceType's Class Extensions' Metadata is missing

[johnsonjo4531]

Describe the Bug
It appears InterfaceTypes do not carry their Class' extensions metadata when queried.

To Reproduce
The below repo contains what happens in regular GraphQL.js and what happens in TypeGraphQL. There is more info on the repo's readme.

https://github.com/johnsonjo4531/type-graphql-issue-interface-extensions

Expected Behavior
The InterfaceType should carry it's extensions metadata when queried

Logs
I currently log in the example repo that the tests fail when they do what they shouldn't and pass when they do what they should.

Environment (please complete the following information):

• OS: Fedora Linux
• Node 22.11.0
• Package version 2.0.0-rc.2
• TypeScript version 5.7.3

Additional Context
Here's the current contents of the repo's readme for better searchability of this issue for others:

Example Repo Showing Issue with TypeGraphQL's Metadata in Interface Types.

This repo has an example in src/index.ts that compares the output of pure graphql.js and type-graphql.
The outputs differ in that the type-graphql does not seem to have the intreface type's extensions metadata along with it this is a bug and prevents me from using
certain libraries along with type-graphql.

Running the example

If you have make available just run the following from the root of the repo:

make

otherwise use the following in your terminal at the root of the repo:

npm i && npm run build && npm run start

Without doing anything you should see the one test failing comparing type-graphql's metadata on the interface to graphql's metadata on the interface.

More on the Underlying Issue

The following someMetadata: true is missing from this InterfaceType's extensions when you try and get the metadata from the query.

src/User.ts

@InterfaceType({
  resolveType(obj) {
    return obj.$type;
  },
})
@Extensions({
  someMetadata: true,
})
export class User {
  @Field({ nullable: true })
  id: number;
}

I also have the following query:

src/QueryRoot.ts

@Resolver(() => Query)
export class QueryRoot {
  @Query(() => User, {
    nullable: true,
  })
  user(@Info() resolveInfo: GraphQLResolveInfo) {
    return {
      id: 1,
    };
  }
}

After the schema is built I expect the metadata to be available on the schema, just as it is on the graphQLSchema (which is the same example schema but in pure graphql.js) but currently it is not in schema... and the below test fails instead of passes.

console.log({
  graphqlHasSomeMetadata: (graphQLSchema as any)._queryType._fields.user.type
    .extensions.someMetadata,
  typeGraphQLHasSomeMetadata: (schema as any)._queryType._fields.user.type
    .extensions?.someMetadata,
});
if (
  (schema as any)._queryType._fields.user.type.extensions?.someMetadata !=
  (graphQLSchema as any)._queryType._fields.user.type.extensions.someMetadata
) {
  throw new Error("TEST FAILED: NO SUCH EXTENSION METADATA in TypeGraphQL!!!");
}
console.log("TEST PASSED! Extension metadata exists just as in GraphQL");

The Info I Can Give at the Moment Towards the Problem.

In the below code as I was stepping through it I noticed that interfaceType.type does not have the metadata but interfaceType.metadata does!
I'm not sure what the difference is between those two, but I thought this information would help.

type-graphql/build/esm/schema.js

// elided...
export class SchemaGenerator {
    // elided...
    static getGraphQLOutputType(target, propertyName, type, typeOptions = {}) {
        let gqlType;
        gqlType = convertTypeIfScalar(type);
        // elided...
        if (!gqlType) {
            const interfaceType = this.interfaceTypesInfo.find(it => it.target === type);
            if (interfaceType) {
                this.usedInterfaceTypes.add(interfaceType.target);
                // Around line 509 This interfaceType.type does not have the metadata but interfaceType.metadata does!!!
                gqlType = interfaceType.type;
            }
        }
        // elided...
        const { nullableByDefault } = BuildContext;
        return wrapWithTypeOptions(target, propertyName, gqlType, typeOptions, nullableByDefault);
    }
    // elided...
}
// elided...