Export default SWR config to allow more flexible extensions (#1023)

* Export default SWR config to allow more flexible extensions

* export default config as static property on SWRConfig

Author: jakubriedl

src/use-swr.ts

@@ -804,7 +804,12 @@ function useSWR<Data = any, Error = any>(
   return memoizedState
 }
 
-const SWRConfig = SWRConfigContext.Provider
+Object.defineProperty(SWRConfigContext.Provider, 'default', {
+  value: defaultConfig
+})
+const SWRConfig = SWRConfigContext.Provider as typeof SWRConfigContext.Provider & {
+  default: SWRConfiguration
+}
 
 export { trigger, mutate, SWRConfig }
 export default useSWR

test/use-swr-configs.test.tsx

@@ -2,6 +2,7 @@ import { act, render, screen, fireEvent } from '@testing-library/react'
 import React, { useEffect, useState } from 'react'
 import useSWR, { mutate, SWRConfig } from '../src'
 import { sleep } from './utils'
+import defaultConfig from '../src/config'
 
 describe('useSWR - configs', () => {
   it('should read the config fallback from the context', async () => {
@@ -88,4 +89,8 @@ describe('useSWR - configs', () => {
     await act(() => revalidate())
     screen.getByText('data: 1')
   })
+
+  it('should expose default config as static property on SWRConfig', () => {
+    expect(SWRConfig.default).toBe(defaultConfig)
+  })
 })