fix(query-core): ensureQueryData should not call fetchQuery for queri…

…es with falsy data (#6261)

* fix(query-core): ensureQueryData call fetchQuery when the query actually does not exist

* fix: all the returned data covered by the test case to be falsy values

---------

Co-authored-by: goo <goo@tossbank.com>

packages/query-core/src/queryClient.ts

@@ -132,7 +132,9 @@ export class QueryClient {
   ): Promise<TData> {
     const cachedData = this.getQueryData<TData>(options.queryKey)
 
-    return cachedData ? Promise.resolve(cachedData) : this.fetchQuery(options)
+    return cachedData !== undefined
+      ? Promise.resolve(cachedData)
+      : this.fetchQuery(options)
   }
 
   getQueriesData<TQueryFnData = unknown>(

packages/query-core/src/tests/queryClient.test.tsx

@@ -433,6 +433,17 @@ describe('queryClient', () => {
       ).resolves.toEqual('bar')
     })
 
+    test('should return the cached query data if the query is found and cached query data is falsey', async () => {
+      const key = queryKey()
+      const queryFn = () => Promise.resolve(0)
+
+      queryClient.setQueryData([key, 'id'], null)
+
+      await expect(
+        queryClient.ensureQueryData({ queryKey: [key, 'id'], queryFn }),
+      ).resolves.toEqual(null)
+    })
+
     test('should call fetchQuery and return its results if the query is not found', async () => {
       const key = queryKey()
       const queryFn = () => Promise.resolve('data')