Fix: type support for suspense and fallbackData(#2396)

_internal/types.ts

@@ -232,27 +232,23 @@ export interface SWRHook {
     SWRKey extends Key = StrictKey,
     SWROptions extends
       | SWRConfiguration<Data, Error, Fetcher<Data, SWRKey>>
-      | undefined =
-      | SWRConfiguration<Data, Error, Fetcher<Data, SWRKey>>
-      | undefined
+      | undefined = SWRConfiguration<Data, Error, Fetcher<Data, SWRKey>>
   >(
     key: SWRKey,
-    config: SWROptions
-  ): SWRResponse<Data, Error, SWROptions>
+    config: SWROptions | undefined
+  ): SWRResponse<Data, Error, Required<SWROptions>>
   <
     Data = any,
     Error = any,
     SWRKey extends Key = StrictKey,
     SWROptions extends
       | SWRConfiguration<Data, Error, Fetcher<Data, SWRKey>>
-      | undefined =
-      | SWRConfiguration<Data, Error, Fetcher<Data, SWRKey>>
-      | undefined
+      | undefined = SWRConfiguration<Data, Error, Fetcher<Data, SWRKey>>
   >(
     key: SWRKey,
     fetcher: Fetcher<Data, SWRKey> | null,
-    config: SWROptions
-  ): SWRResponse<Data, Error, SWROptions>
+    config: SWROptions | undefined
+  ): SWRResponse<Data, Error, Required<SWROptions>>
   <Data = any, Error = any>(key: Key): SWRResponse<Data, Error>
   <Data = any, Error = any>(
     key: Key,
@@ -263,22 +259,22 @@ export interface SWRHook {
     Error = any,
     SWROptions extends
       | SWRConfiguration<Data, Error, BareFetcher<Data>>
-      | undefined = SWRConfiguration<Data, Error, BareFetcher<Data>> | undefined
+      | undefined = SWRConfiguration<Data, Error, BareFetcher<Data>>
   >(
     key: Key,
-    config: SWROptions
-  ): SWRResponse<Data, Error, SWROptions>
+    config: SWROptions | undefined
+  ): SWRResponse<Data, Error, Required<SWROptions>>
   <
     Data = any,
     Error = any,
     SWROptions extends
       | SWRConfiguration<Data, Error, BareFetcher<Data>>
-      | undefined = SWRConfiguration<Data, Error, BareFetcher<Data>> | undefined
+      | undefined = SWRConfiguration<Data, Error, BareFetcher<Data>>
   >(
     key: Key,
     fetcher: BareFetcher<Data> | null,
-    config: SWROptions
-  ): SWRResponse<Data, Error, SWROptions>
+    config: SWROptions | undefined
+  ): SWRResponse<Data, Error, Required<SWROptions>>
 }
 
 // Middleware guarantees that a SWRHook receives a key, fetcher, and config as the argument

test/type/config.tsx

@@ -2,7 +2,11 @@ import React from 'react'
 import type { Cache, SWRResponse } from 'swr'
 import useSWR, { useSWRConfig, SWRConfig } from 'swr'
 import { expectType } from './utils'
-import type { FullConfiguration } from 'swr/_internal'
+import type {
+  BareFetcher,
+  FullConfiguration,
+  PublicConfiguration
+} from 'swr/_internal'
 import type { Equal } from '@type-challenges/utils'
 
 export function testCache() {
@@ -53,13 +57,45 @@ export function testSWRResponseCachedDataTypes() {
 }
 
 export function testSuspense() {
-  const { data: suspenseyData } = useSWR(
+  // Basic
+  const { data: data1 } = useSWR('/api', (k: string) => Promise.resolve(k), {
+    suspense: true
+  })
+  expectType<string>(data1)
+
+  // Basic(default fetcher)
+  const { data: data2 } = useSWR('/api', {
+    suspense: true
+  })
+  expectType<any>(data2)
+
+  // Generics
+  const { data: data3 } = useSWR<string>(
     '/api',
     (k: string) => Promise.resolve(k),
     { suspense: true }
   )
+  expectType<string>(data3)
+
+  // Generics(default fetcher)
+  const { data: data4 } = useSWR<string>('/api', { suspense: true })
+  expectType<string>(data4)
+
+  // Generics(SWRKey)
+  const { data: data5 } = useSWR<string, any, '/api'>(
+    '/api',
+    (k: string) => Promise.resolve(k),
+    {
+      suspense: true
+    }
+  )
+  expectType<string>(data5)
 
-  expectType<string>(suspenseyData)
+  // Generics(SWRKey, default fetcher)
+  const { data: data6 } = useSWR<string, any, '/api'>('/api', {
+    suspense: true
+  })
+  expectType<string>(data6)
 }
 
 export function testFallbackData() {
@@ -86,4 +122,45 @@ export function testFallbackData() {
     fallbackData: { value: 'fallback' }
   })
   expectType<{ value: string }>(data3)
+
+  // Does not need specific fetcher
+
+  // Basic(default fetcher)
+  const { data: data4 } = useSWR('/api', { fallbackData: 'fallback' })
+  expectType<any>(data4)
+
+  // Generics
+  const { data: data5 } = useSWR<string>(
+    '/api',
+    (k: string) => Promise.resolve(k),
+    { fallbackData: 'fallback' }
+  )
+  expectType<string>(data5)
+
+  // Generics(default fetcher)
+  const { data: data6 } = useSWR<string>('/api', { fallbackData: 'fallback' })
+  expectType<string>(data6)
+
+  // Generics(SWRKey)
+  const { data: data7 } = useSWR<string, any, '/api'>(
+    '/api',
+    (k: string) => Promise.resolve(k),
+    { fallbackData: 'fallback' }
+  )
+  expectType<string>(data7)
+
+  // Generics(SWRKey, default fetcher)
+  const { data: data8 } = useSWR<string, any, '/api'>('/api', {
+    fallbackData: 'fallback'
+  })
+  expectType<string>(data8)
+}
+export function testUndefined() {
+  // Undefined can be passed to config.
+  expectType<
+    Equal<
+      Parameters<typeof useSWR<string, any>>['2'],
+      Partial<PublicConfiguration<string, any, BareFetcher<string>>> | undefined
+    >
+  >(true)
 }