PrismockClient type is incorrect

[electrovir]

Problem

This type cast is incorrect:

prismock/src/lib/client.ts

Line 116 in 1b3baeb

} as unknown as typeof PrismaClient & PrismockData;

It's intersecting the PrismockData interface as a static interface, not an instance interface.

What I mean by that is that with the current types, this is a type error (but not a run-time error):

const client = new PrismockClient();
client.getData();

while this is not a type error but is a run-time error:

const client = new PrismockClient();
PrismockClient.getData();

Solution

You basically need to unwrap and rewrap the PrismaClient constructor so you can modify the returned instance type. There might be a more elegant way of doing this, but this is working for me:

import type {Constructor} from 'type-fest';

type RealPrismockClient = Constructor<
    PrismaClient & PrismockData,
    ConstructorParameters<typeof PrismaClient>
>;

Note that if you don't want to include the type-fest dependency, the Constructor type that it exports is as follows:

export type Constructor<T, Arguments extends unknown[] = any[]> = new(...arguments_: Arguments) => T;

[morintd]

Hello @electrovir , thanks a lot! I'll think about the best way to fix that and try to get something done in the next few days