Jest integration nested values

[alexnsorensen]

Question

I'm using Jest and jest-mock-extended to do unit testing on some more complex functions in my code. However I ran into an issue where I need to get nested data or something from prisma. and I can't see anything on Prisma's official website about this and couldn't see anything, I also had a read through this article

For example:

primsa.person.findFirstOrThrow({where: {id: 1}}).posts()`

When I just run this code:

primsa.person.findFirstOrThrow({where: {id: 1}})

Jest works great and gets the mocked data, but when I add the .posts() I get an error saying TypeError: person.posts is not a function.

I do my mocked person data like so:

mockPrisma.person.findUniqueOrThrow.mockResolvedValue({
    id: 1
    name: 'John Smith'
});

I understand why this error occurs, but I can't work out the syntax to get the mocked posts in there as everything I try throws a TS error.

Things I tried (assume data between the []):

mockPrisma.person.findUniqueOrThrow.mockResolvedValue({
    id: 1
    name: 'John Smith',
    posts: mockPrisma.post.findMany.mockResolvedValue([]);
});

////////////////////////////////////////////////////

mockPrisma.post.findMany.mockResolvedValue([])

mockPrisma.person.findUniqueOrThrow.mockResolvedValue({
    id: 1
    name: 'John Smith',
    posts: mockPrisma.post.findMany
});

How to reproduce (optional)

Expected behavior (optional)

No response

Information about Prisma Schema, Client Queries and Environment (optional)

No response

[ludralph]

Hi @alexnsorensen 👋

Thank you for raising this question.

Can you use mockReturnValue for the first call instead of mockResolvedValue?

prismaMock.person.findUniqueOrThrow.mockReturnValue({
    posts: jest.fn().mockResolvedValue(posts),
});

[alexnsorensen]

Hi, what I ended up having to do was this:

prismaMock.person.findUniqueOrThrow.mockReturnValue({
    posts: jest.fn().mockResolvedValue(posts),
    then: jest.fn().mockReturnValue(Promise.resolve(mockedPerson))(),
    catch: jest.fn().mockResolvedValue(null),
    finally: jest.fn().mockResolvedValue(mockedPerson)(),
    [Symbol.toStringTag]: 'PrismaPromise',
});

If I didn't add these then I would get a tonne of TS errors, so I Imagine it's to do with my TS settings probably being rather strict...

[raphaelumoh]

Thank you for sharing the final outcome. It's really helpful.