Pre-populate QueryClient cache with Zod schema-valid data for tests. No fetch mocking needed

[gonll]

Hey everyone, I wanted to share a small testing utility I built that pairs well
with TanStack Query projects already using Zod for schema validation.

The problem

Testing components that depend on queries usually means one of:

• Wrapping in a real QueryClientProvider and mocking fetch / MSW
• Hand-writing fixture objects that drift from your actual schemas over time

If you're already using Zod to validate API responses, your schemas are the
source of truth, so why not generate test data directly from them?

What I built

zodmint/tanstack-query pre-populates a QueryClient cache synchronously
using your Zod schemas. No network, no fetch mock, no MSW required.

import { mockQueryClient } from "zodmint/tanstack-query";

const client = mockQueryClient([
  { queryKey: ["user", "1"], schema: UserSchema },
  { queryKey: ["posts"],     schema: z.array(PostSchema) },
]);

render(
  <QueryClientProvider client={client}>
    <UserProfile userId="1" />
  </QueryClientProvider>
);
// component renders immediately with valid, schema-conforming data

The client comes with test-friendly defaults (retry: false, staleTime: Infinity,
gcTime: Infinity) and every generated value is guaranteed to pass
schema.safeParse(v).success === true.

There's also mockQueryFn for dropping into useQuery directly, and
mockInfiniteQueryClient for infinite query testing with the v5
{ pages, pageParams } shape.

Install

npm install zodmint
# @tanstack/query-core is the only peer dep (you already have it)

import { mockQueryClient, mockQueryFn, mockInfiniteQueryClient } from "zodmint/tanstack-query";

Full docs: github.com/gonll/zodmint

Would love feedback, especially from anyone doing complex query testing patterns
I might have missed.