refactor: remove unused query.setDefaultOptions

Author: TkDodo

docs/src/pages/guides/migrating-to-react-query-4.md

@@ -217,9 +217,9 @@ The `useQueries` hook now accepts an object with a `queries` prop as its input.
 ```
 
 
-### Removed undocumented methods from the `queryClient`
+### Removed undocumented methods from the `queryClient` and `query`
 
-The methods `cancelMutatations` and `executeMutation` were undocumented and unused internally, so we removed them. Since they were just wrappers around methods available on the `mutationCache`, you can still use the functionality.
+The methods `cancelMutatations` and `executeMutation` on the `QueryClient` were undocumented and unused internally, so we removed them. Since they were just wrappers around methods available on the `mutationCache`, you can still use the functionality.
 
 ```diff
 - cancelMutations(): Promise<void> {
@@ -243,6 +243,8 @@ The methods `cancelMutatations` and `executeMutation` were undocumented and unus
 - }
 ```
 
+Additionally, `query.setDefaultOptions` was removed because it was also unused.
+
 ### TypeScript
 
 Types now require using TypeScript v4.1 or greater

src/core/query.ts

@@ -188,12 +188,6 @@ export class Query<
     this.updateCacheTime(this.options.cacheTime)
   }
 
-  setDefaultOptions(
-    options: QueryOptions<TQueryFnData, TError, TData, TQueryKey>
-  ): void {
-    this.defaultOptions = options
-  }
-
   protected optionalRemove() {
     if (!this.observers.length && this.state.fetchStatus === 'idle') {
       this.cache.remove(this)

src/core/tests/query.test.tsx

@@ -634,21 +634,6 @@ describe('query', () => {
     )
   })
 
-  test('should set default options', async () => {
-    const key = queryKey()
-
-    await queryClient.prefetchQuery(key, () => 'data')
-    const query = queryCache.find(key)!
-
-    query.setDefaultOptions({ retryDelay: 20 })
-
-    await queryClient.prefetchQuery(key, () => 'data', {
-      cacheTime: 100,
-    })
-
-    expect(query.options).toMatchObject({ cacheTime: 100, retryDelay: 20 })
-  })
-
   test('should refetch the observer when online method is called', async () => {
     const key = queryKey()