Typescript circular reference when testing prisma with jest-mock-extended

Question

I started writting tests revolving around prisma(v3.6.0) usage in my application.

To do so I followed the official prisma page Unit testing with prisma and I am using jest-mock-extended.

My issue is that I have a typescript error when using the mocked prisma functions :

describe('User routes', () => {
    it('should respond success with array of users', async () => {
        prismaMock.user.findMany.mockResolvedValue([]); // <- here is the error
    }
}

Type of property 'AND' circularly references itself in mapped type 

There is some discussion about this issue on github Testing with prisma. I got 3 options from this discussion :

• Adding "skipLibCheck": true in tsconfig.json. This breaks some things in my code and doesn't resolve my issue
• Adding "strictNullChecks": true, no effect either
• //@ts-ignore the line. This effectively remove the error, and the test runs smoothly

While I am able to do my tests, I would like not to have to ignore this error everywhere in my tests, and ignoring errors is only a good idea until it's not.

Does someone have more information or recommendations about this issue ?

Answer 1

Set the "stricNullChecks": true in your tsconfig.json, it is highlighted on prisma documentation for the circular dependency error.

https://www.prisma.io/docs/orm/prisma-client/testing/unit-testing