Fix initial isValidating when isPaused() returns true (#1440)

* Fix initial isValidating when isPaused returns true

* Update unit test description

src/use-swr.ts

@@ -85,11 +85,13 @@ export const useSWRHandler = <Data = any, Error = any>(
 
   // A revalidation must be triggered when mounted if:
   // - `revalidateOnMount` is explicitly set to `true`.
+  // - `isPaused()` returns to `true`.
   // - Suspense mode and there's stale data for the initial render.
   // - Not suspense mode and there is no fallback data and `revalidateIfStale` is enabled.
   // - `revalidateIfStale` is enabled but `data` is not defined.
   const shouldRevalidateOnMount = () => {
     if (!isUndefined(revalidateOnMount)) return revalidateOnMount
+    if (configRef.current.isPaused()) return false
 
     return suspense
       ? !initialMountedRef.current && !isUndefined(data)

test/use-swr-revalidate.test.tsx

@@ -136,4 +136,19 @@ describe('useSWR - revalidate', () => {
     await act(() => sleep(70))
     screen.getByText('count: 2')
   })
+
+  it('should set initial isValidating be false when config.isPaused returns true', async () => {
+    function Page() {
+      const { isValidating } = useSWR(
+        'set isValidating for config.isPaused',
+        () => '123',
+        { isPaused: () => true }
+      )
+
+      return <div>{isValidating ? 'true' : 'false'}</div>
+    }
+
+    render(<Page />)
+    screen.getByText('false')
+  })
 })