From 1be78f778089c38ae20170550f81c35e37c39691 Mon Sep 17 00:00:00 2001
From: Yixuan Xu <yixuanxu94@outlook.com>
Date: Thu, 21 Apr 2022 06:13:14 +0800
Subject: [PATCH] type: extends useConfig cache interface (#1938)

---
 src/types.ts                |  7 ++++---
 src/utils/use-swr-config.ts |  6 ++++--
 test/type/config.ts         | 12 ++++++++++++
 3 files changed, 20 insertions(+), 5 deletions(-)
 create mode 100644 test/type/config.ts

diff --git a/src/types.ts b/src/types.ts
index 0dea512cd..37638f555 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -17,8 +17,8 @@ export type Fetcher<
   : never
 
 // Configuration types that are only used internally, not exposed to the user.
-export interface InternalConfiguration {
-  cache: Cache
+export interface InternalConfiguration<T extends Cache = Cache> {
+  cache: T
   mutate: ScopedMutator
 }
 
@@ -77,7 +77,8 @@ export interface PublicConfiguration<
   isVisible: () => boolean
 }
 
-export type FullConfiguration = InternalConfiguration & PublicConfiguration
+export type FullConfiguration<T extends Cache = Cache> =
+  InternalConfiguration<T> & PublicConfiguration
 
 export type ProviderConfiguration = {
   initFocus: (callback: () => void) => (() => void) | void
diff --git a/src/utils/use-swr-config.ts b/src/utils/use-swr-config.ts
index 24814006e..a12ec7b73 100644
--- a/src/utils/use-swr-config.ts
+++ b/src/utils/use-swr-config.ts
@@ -2,8 +2,10 @@ import { useContext } from 'react'
 import { defaultConfig } from './config'
 import { SWRConfigContext } from './config-context'
 import { mergeObjects } from './helper'
-import { FullConfiguration } from '../types'
+import { FullConfiguration, Cache } from '../types'
 
-export const useSWRConfig = (): FullConfiguration => {
+export const useSWRConfig = <
+  T extends Cache = Map<string, any>
+>(): FullConfiguration<T> => {
   return mergeObjects(defaultConfig, useContext(SWRConfigContext))
 }
diff --git a/test/type/config.ts b/test/type/config.ts
new file mode 100644
index 000000000..54a9ff9f7
--- /dev/null
+++ b/test/type/config.ts
@@ -0,0 +1,12 @@
+import { useSWRConfig, Cache } from 'swr'
+import { expectType } from './utils'
+
+interface CustomCache<Data = any> extends Cache<Data> {
+  reset(): void
+}
+
+export function useTestCache() {
+  expectType<Map<string, any>>(useSWRConfig().cache)
+  expectType<Map<string, number>>(useSWRConfig<Map<string, number>>().cache)
+  expectType<CustomCache>(useSWRConfig<CustomCache>().cache)
+}