fix: isLoading and isValidating should always respect cache value (#2048

)

* fix: isLoading and isValidating should always respect cache value

fix #2030

* test: case for #2030

core/use-swr.ts

@@ -204,8 +204,8 @@ export const useSWRHandler = <Data = any, Error = any>(
     isInitialMount &&
     shouldDoInitialRevalidation
   )
-  const isValidating = cached.isValidating || defaultValidatingState
-  const isLoading = cached.isLoading || defaultValidatingState
+  const isValidating = isUndefined(cached.isValidating) ? defaultValidatingState : cached.isValidating
+  const isLoading = isUndefined(cached.isLoading) ? defaultValidatingState : cached.isLoading
 
   // The revalidation function is a carefully crafted wrapper of the original
   // `fetcher`, to correctly handle the many edge cases.

test/use-swr-loading.test.tsx

@@ -318,4 +318,23 @@ describe('useSWR - loading', () => {
     screen.getByText('loading,validating')
     await screen.findByText('ready,ready')
   })
+  it('isLoading and isValidating should always respect cache value', async () => {
+    const key = createKey()
+    const Page = () => {
+      const { data } = useSWR(key, () => createResponse('result', { delay: 10 }))
+      const { data: response } = useSWR(data, () => createResponse('data', { delay: 10 }))
+      // eslint-disable-next-line react/display-name
+      const Component = ((_: any) => () => {
+        // eslint-disable-next-line react-hooks/rules-of-hooks
+        const { data: result, isLoading, isValidating } = useSWR(key, () => createResponse('result', { delay: 10 }))
+        return (
+          <div>{`result is ${result ? result : 'null'},${isLoading},${isValidating}`}</div>
+        )
+      })(response)
+      return <Component></Component>
+    }
+    renderWithConfig(<Page />)
+    screen.getByText('result is null,true,true')
+    await screen.findByText('result is result,false,false')
+  })
 })