test(query-core/utils): add tests for 'ensureQueryFn' initialPromise fallback and skipToken handling

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: KimHyeongRae0

packages/query-core/src/__tests__/utils.test.tsx

@@ -4,6 +4,7 @@ import { QueryClient } from '..'
 import {
   addToEnd,
   addToStart,
+  ensureQueryFn,
   hashKey,
   hashQueryKeyByOptions,
   isPlainArray,
@@ -14,6 +15,7 @@ import {
   replaceEqualDeep,
   shallowEqualObjects,
   shouldThrowError,
+  skipToken,
 } from '../utils'
 import { Mutation } from '../mutation'
 
@@ -534,6 +536,57 @@ describe('core/utils', () => {
     })
   })
 
+  describe('ensureQueryFn', () => {
+    it('should return a function that resolves to initialPromise when queryFn is missing and initialPromise is provided', async () => {
+      const initialPromise = Promise.resolve('initial-data')
+
+      const resolved = ensureQueryFn(
+        { queryHash: '["key"]' },
+        { initialPromise },
+      )
+
+      await expect(
+        (resolved as unknown as () => Promise<string>)(),
+      ).resolves.toBe('initial-data')
+    })
+
+    it('should return a function that rejects when initialPromise rejects', async () => {
+      const error = new Error('initial-promise-error')
+      const initialPromise = Promise.reject(error)
+
+      const resolved = ensureQueryFn(
+        { queryHash: '["key"]' },
+        { initialPromise },
+      )
+
+      await expect(
+        (resolved as unknown as () => Promise<unknown>)(),
+      ).rejects.toBe(error)
+    })
+
+    it('should return a function that rejects with missing queryFn error when queryFn is set to skipToken', async () => {
+      const consoleErrorSpy = vi
+        .spyOn(console, 'error')
+        .mockImplementation(() => undefined)
+
+      const resolved = ensureQueryFn({
+        queryFn: skipToken,
+        queryHash: '["skip"]',
+      })
+
+      expect(consoleErrorSpy).toHaveBeenCalledWith(
+        expect.stringContaining(
+          'Attempted to invoke queryFn when set to skipToken',
+        ),
+      )
+      await expect(
+        (resolved as unknown as () => Promise<unknown>)(),
+      ).rejects.toThrow('Missing queryFn: \'["skip"]\'')
+
+      consoleErrorSpy.mockRestore()
+    })
+  })
+
   describe('shouldThrowError', () => {
     it('should return the result of executing throwOnError if throwOnError parameter is a function', () => {
       const throwOnError = (error: Error) => error.message === 'test error'