typescript: Dates in controller response are not Dates but are strings; numbers are numbers though

[small pebble]

I have a response object that looks like this
class MyResponse {
id: string;
qty: number;
paid: Date;
}

My controller looks like
@Get("/test")
async test(): Promise<MyResponse> {
const res: MyResponse = {
id: 'hi',
qty: 1,
paid: new Date(),
}
return res;
}

In my swagger and in my unit test however, my responses look like
{
id: 'hi',
qty: 1,
paid: 'string-ified version'
}

The qty is coming across as a number but why is the date coming across as not a Date object? Why is it a string? I'm asking because I can't get my e2e test to pass because of the type mis-match. I would really prefer it to be of type Date and not string anyway. Is there a way to force nest to serialize it properly? I've tried adding a ValidationPipe to that endpoint as well as having an @Transform on my paid field.

[amber cradle]

Because JSON does not have a Date type.

[small pebble]

That's true, I just assumed that the nestjs e2e test harness (as documented) would have transformed Dates into Dates

[echo pawn]

Transformation into Date must be performed on the client. Nest has no power there. It would be wrong to transform it in tests and have it break in a real application

[small pebble]

So how does one perform assertions on dates? I had hoped to just one-line it with a jest expect(expectedResponse).toStrictEqual(actoualResponse)
In my real life example the objects are very complicated with lots of nested arrays of objects and dates all over.

We're talking hundreds of fields. So doing individual expects on every field in the response isn't going to be maintainable.