6 files changed, 56 insertions, 12 deletions
diff --git a/jest.config.ts b/jest.config.ts
index 1c6e6c1..838b86c 100644
--- a/jest.config.ts
+++ b/jest.config.ts
@@ -1,8 +1,7 @@
 import type { Config } from 'jest'
 
 const config: Config = {
-  preset: 'ts-jest',
-  roots: ['<rootDir>/src']
+  preset: 'ts-jest'
 }
 
 export default config
diff --git a/package.json b/package.json
index 0e2ccfe..e4f0298 100644
--- a/package.json
+++ b/package.json
@@ -18,10 +18,12 @@
   "author": "Zhineng Li",
   "type": "module",
   "main": "dist/index.js",
+  "types": "dist/index.d.ts",
   "scripts": {
     "build": "tsc",
     "test": "jest",
     "test:watch": "jest --watch",
+    "test:types": "tsd --files tests/**/*.test-d.ts",
     "format": "prettier --write --cache ."
   },
   "devDependencies": {
@@ -31,6 +33,7 @@
     "prettier": "3.6.2",
     "ts-jest": "^29.4.0",
     "ts-node": "^10.9.2",
+    "tsd": "^0.32.0",
     "typescript": "^5.8.3"
   }
 }
diff --git a/src/index.ts b/src/index.ts
index 04a1870..de0ad68 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -3,7 +3,9 @@ type QueryString = Record<string, string>
 type HttpMethod = WechatMiniprogram.RequestOption['method']
 type RequestTask = WechatMiniprogram.RequestTask | WechatMiniprogram.UploadTask
 type RequestData = Record<string, unknown>
-type ResponseData = WechatMiniprogram.RequestSuccessCallbackResult['data']
+type ResponseData =
+  | WechatMiniprogram.RequestSuccessCallbackResult['data']
+  | WechatMiniprogram.UploadFileSuccessCallbackResult['data']
 type MiddlewareNext<T extends ResponseData> = (
   request: PendingRequest
 ) => RequestPromise<Response<SuccessCallbackResult<T>, T>>
@@ -87,7 +89,7 @@ class PendingRequest {
 
   #data: RequestData = {}
 
-  #middlewares: Middleware<any>[] = []
+  #middlewares: Middleware<ResponseData>[] = []
 
   method(method: HttpMethod) {
     const request = this.#clone()
@@ -192,7 +194,12 @@ class PendingRequest {
 
     return this.#throughMiddlewares(request)(
       this.#dispatchUpload(option.name, option.filePath)
-    )
+    ) as RequestPromise<
+      Response<
+        WechatMiniprogram.UploadFileSuccessCallbackResult,
+        WechatMiniprogram.UploadFileSuccessCallbackResult['data']
+      >
+    >
   }
 
   #dispatchUpload(name: string, filePath: string) {
@@ -232,10 +239,12 @@ class PendingRequest {
     }
   }
 
-  #send<T extends ResponseData>(): RequestPromise<
-    Response<SuccessCallbackResult<T>, T>
-  > {
-    return this.#throughMiddlewares<T>(this)(this.#dispatchRequest<T>)
+  #send<T extends ResponseData>() {
+    return this.#throughMiddlewares<T>(this)(
+      this.#dispatchRequest<T>
+    ) as RequestPromise<
+      Response<WechatMiniprogram.RequestSuccessCallbackResult<T>, T>
+    >
   }
 
   #dispatchRequest<T extends ResponseData>(request: PendingRequest) {
@@ -274,7 +283,7 @@ class PendingRequest {
     return (handler: MiddlewareNext<T>) =>
       this.#middlewares.reduceRight(
         (next: MiddlewareNext<T>, middleware) => (request: PendingRequest) =>
-          middleware(request, next),
+          (middleware as Middleware<T>)(request, next),
         handler
       )(request)
   }
diff --git a/tests/index.test-d.ts b/tests/index.test-d.ts
new file mode 100644
index 0000000..52df93c
--- /dev/null
+++ b/tests/index.test-d.ts
@@ -0,0 +1,32 @@
+import { expectType } from 'tsd'
+import { Client } from '../src'
+
+interface User {
+  name: string
+}
+
+;async () => {
+  const response = await Client.new().get('http://example.com')
+  expectType<WechatMiniprogram.RequestSuccessCallbackResult['data']>(
+    response.data()
+  )
+}
+
+;async () => {
+  const response = await Client.new().get<User>('http://example.com')
+  expectType<User>(response.data())
+}
+
+;async () => {
+  const response = await Client.new().get<string>('http://example.com/string')
+  expectType<string>(response.data())
+}
+
+;async () => {
+  const response = await Client.new().upload({
+    url: 'http://example.com',
+    filePath: '/tmp/foo.txt',
+    name: 'file'
+  })
+  expectType<string>(response.data())
+}
diff --git a/src/index.test.ts b/tests/index.test.ts
index 8d73700..c8e0a64 100644
--- a/src/index.test.ts
+++ b/tests/index.test.ts
@@ -1,4 +1,4 @@
-import { Factory, Response } from './'
+import { Factory, Response } from '../src'
 
 describe('HTTP Client', () => {
   beforeEach(() => {
diff --git a/tsconfig.json b/tsconfig.json
index d5c5877..6b51bae 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -15,5 +15,6 @@
       "./node_modules/miniprogram-api-typings"
     ]
   },
-  "include": ["src/**/*.ts"]
+  "include": ["src"],
+  "exclude": ["*.test.ts", "*.test-d.ts"]
 }