import { describe, expectTypeOf, it } from 'vitest' import { QueryClient } from '@tanstack/query-core' import { useMutation } from '../useMutation' import type { DefaultError } from '@tanstack/query-core' import type { UseMutationResult } from '../types' describe('useMutation', () => { it('should infer TData from mutationFn return type', () => { const mutation = useMutation({ mutationFn: () => Promise.resolve('data'), }) expectTypeOf(mutation.data).toEqualTypeOf() expectTypeOf(mutation.error).toEqualTypeOf() }) it('should infer TVariables from mutationFn parameter', () => { const mutation = useMutation({ mutationFn: (vars: { id: string }) => Promise.resolve(vars.id), }) expectTypeOf(mutation.mutate).toBeCallableWith({ id: '1' }) expectTypeOf(mutation.data).toEqualTypeOf() }) it('should infer TOnMutateResult from onMutate return type', () => { useMutation({ mutationFn: () => Promise.resolve('data'), onMutate: () => { return { token: 'abc' } }, onSuccess: (_data, _variables, onMutateResult) => { expectTypeOf(onMutateResult).toEqualTypeOf<{ token: string }>() }, onError: (_error, _variables, onMutateResult) => { expectTypeOf(onMutateResult).toEqualTypeOf< { token: string } | undefined >() }, }) }) it('should allow explicit generic types', () => { const mutation = useMutation({ mutationFn: (vars) => { expectTypeOf(vars).toEqualTypeOf<{ id: number }>() return Promise.resolve('result') }, }) expectTypeOf(mutation.data).toEqualTypeOf() expectTypeOf(mutation.error).toEqualTypeOf() }) it('should return correct UseMutationResult type', () => { const mutation = useMutation({ mutationFn: () => Promise.resolve(42), }) expectTypeOf(mutation).toEqualTypeOf< UseMutationResult >() }) it('should type mutateAsync with correct return type', () => { const mutation = useMutation({ mutationFn: (id: string) => Promise.resolve(id.length), }) expectTypeOf(mutation.mutateAsync).toBeCallableWith('test') expectTypeOf(mutation.mutateAsync('test')).toEqualTypeOf>() }) it('should default TVariables to void when mutationFn has no parameters', () => { const mutation = useMutation({ mutationFn: () => Promise.resolve('data'), }) expectTypeOf(mutation.mutate).toBeCallableWith() }) it('should infer custom TError type', () => { class CustomError extends Error { code: number constructor(code: number) { super() this.code = code } } const mutation = useMutation({ mutationFn: () => Promise.resolve('data'), }) expectTypeOf(mutation.error).toEqualTypeOf() expectTypeOf(mutation.data).toEqualTypeOf() }) it('should infer types for onSettled callback', () => { useMutation({ mutationFn: () => Promise.resolve(42), onSettled: (data, error, _variables, _onMutateResult) => { expectTypeOf(data).toEqualTypeOf() expectTypeOf(error).toEqualTypeOf() }, }) }) it('should infer custom TError in onError callback', () => { class CustomError extends Error { code: number constructor(code: number) { super() this.code = code } } useMutation({ mutationFn: () => Promise.resolve('data'), onError: (error) => { expectTypeOf(error).toEqualTypeOf() }, }) }) it('should accept queryClient as second argument', () => { const queryClient = new QueryClient() const mutation = useMutation( { mutationFn: () => Promise.resolve('data'), }, queryClient, ) expectTypeOf(mutation.data).toEqualTypeOf() }) })