Unit testing a method decorator created using createMethodDecorator

[ib-tfenright]

I have a factory function that uses the createMethodDecorator method to create a decorator that looks like this:

export function deco() {
    console.log("method decorated at start time");
    return createMethodDecorator(async ({ root, args, context, info }, next) => {
        console.log("decorated method was called");
        const { authorizedUser } = context as IGraphQLContext;
        // some stuff using the authorized user...
        return next();
    });
}

and a test class inside of my jest .test.ts that uses it that looks like this:

class ResolverTest {
    @deco()
    async resolve(
        context: IGraphQLContext,
        entity: TestEntity
    ): Promise<TestEntity> {
        Console.log("resolve method called");
        return entity;
    }
}

The TestEntity is a simple class with a single field called "id".

and then finally, a set of expectations and a call to it that looks like this:

describe('methodDecorator', () => {
    it('should execute the log statement for when the decorated method is executed', () => {
        // setup
        const entity: TestEntity = new TestEntity();
        const resolver: ResolverTest = new ResolverTest();
       
        // call
       resolver.resolve(entity);
    });
});

My basic understanding of standard typescript decorators was that upon calling resolve, I would see the following order of log messages:

• method decorated at start time
• decorated method was called
• resolve method called

However, I only see the first and last messages. If I use a standard typescript decorator factory method like so:

export function deco() {
    console.log("method decorated at start time";
    return function(target: Object, name: PropertyKey) {
        console.log("decorated method was called");
    }
}

I see the messages in the order I described. I need the authorizedUser from the IGraphQLContext, so I can't revert back to the standard decorator syntax.

I know the decorator works because when I use it on an actual resolver within a service, I see the messages I expect. I don't know how why in the context of a test it isn't working, though. I've tried decorating the resolver and entity like one of our actual production resolvers and entities, but that also didn't work. I also tried a few different permutations of declaring the decorator as a variable and trying to call it myself, with no success.

I went looking through the docs and found several examples of how to use the createMethodDecorator method, but came up short finding unit test code to exercise them. Hoping I'm missing something simple.

Thanks!

[MichalLytek]

TypeGraphQL decorators works inside GraphQL runtime. When you call that resolver methods, it's executed outside the pipeline. So you can't expect next to work as it's a framework initialized function to control execution of middlewares and resolvers.

[ib-tfenright]

I see - sounds like I need to refactor my decorator to extract most of the brains into methods that can be invoked outside of that pipeline. Thank you for the tip.