From 34f0b321a201724be29ddecaa1d8d1d6e13276f2 Mon Sep 17 00:00:00 2001
From: hugeletters <ckuka71@gmail.com>
Date: Sun, 5 Nov 2023 18:16:58 +0100
Subject: [PATCH 1/4] get queries

---
 packages/openapi-fetch/src/index.d.ts | 30 +++++++++++++++++++--------
 1 file changed, 21 insertions(+), 9 deletions(-)

diff --git a/packages/openapi-fetch/src/index.d.ts b/packages/openapi-fetch/src/index.d.ts
index ea042b8de..f90f61fa4 100644
--- a/packages/openapi-fetch/src/index.d.ts
+++ b/packages/openapi-fetch/src/index.d.ts
@@ -39,6 +39,15 @@ export type QuerySerializer<T> = (
 export type BodySerializer<T> = (body: OperationRequestBodyContent<T>) => any;
 
 export type ParseAs = "json" | "text" | "blob" | "arrayBuffer" | "stream";
+export type ParseAsResponse<T, K> = K extends ParseAs
+  ? {
+      json: T;
+      text: Awaited<ReturnType<Response["text"]>>;
+      blob: Awaited<ReturnType<Response["blob"]>>;
+      arrayBuffer: Awaited<ReturnType<Response["arrayBuffer"]>>;
+      stream: Response["body"];
+    }[K]
+  : T;
 
 export interface DefaultParamsOption {
   params?: {
@@ -62,9 +71,12 @@ export type RequestBodyOption<T> = OperationRequestBodyContent<T> extends never
 
 export type FetchOptions<T> = RequestOptions<T> & Omit<RequestInit, "body">;
 
-export type FetchResponse<T> =
+export type FetchResponse<T, O extends FetchOptions<any>> =
   | {
-      data: FilterKeys<SuccessResponse<ResponseObjectMap<T>>, MediaType>;
+      data: ParseAsResponse<
+        FilterKeys<SuccessResponse<ResponseObjectMap<T>>, MediaType>,
+        O["parseAs"]
+      >;
       error?: never;
       response: Response;
     }
@@ -86,13 +98,12 @@ export default function createClient<Paths extends {}>(
   clientOptions?: ClientOptions,
 ): {
   /** Call a GET endpoint */
-  GET<P extends PathsWithMethod<Paths, "get">>(
+  GET<
+    P extends PathsWithMethod<Paths, "get">,
+    O extends FetchOptions<FilterKeys<Paths[P], "get">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "get">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "get">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "get">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "get" extends infer T
@@ -101,7 +112,8 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a PUT endpoint */

From d94905ecdb186bb7275330fea31de513072b83d5 Mon Sep 17 00:00:00 2001
From: hugeletters <ckuka71@gmail.com>
Date: Sun, 5 Nov 2023 18:36:11 +0100
Subject: [PATCH 2/4] tets updates

---
 packages/openapi-fetch/test/index.test.ts   | 20 +++++++++++++------
 packages/openapi-fetch/test/v7-beta.test.ts | 22 +++++++++++++++------
 2 files changed, 30 insertions(+), 12 deletions(-)

diff --git a/packages/openapi-fetch/test/index.test.ts b/packages/openapi-fetch/test/index.test.ts
index 764a17286..935e926b1 100644
--- a/packages/openapi-fetch/test/index.test.ts
+++ b/packages/openapi-fetch/test/index.test.ts
@@ -569,23 +569,28 @@ describe("client", () => {
       it("text", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", { parseAs: "text" });
+        const { data }: { data?: string } = await client.GET("/anyMethod", {
+          parseAs: "text",
+        });
         expect(data).toBe("{}");
       });
 
       it("arrayBuffer", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", {
-          parseAs: "arrayBuffer",
-        });
+        const { data }: { data?: ArrayBuffer } = await client.GET(
+          "/anyMethod",
+          { parseAs: "arrayBuffer" },
+        );
         expect(data instanceof ArrayBuffer).toBe(true);
       });
 
       it("blob", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", { parseAs: "blob" });
+        const { data }: { data?: Blob } = await client.GET("/anyMethod", {
+          parseAs: "blob",
+        });
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
         expect((data as any).constructor.name).toBe("Blob");
       });
@@ -593,7 +598,10 @@ describe("client", () => {
       it("stream", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", { parseAs: "stream" });
+        const { data }: { data?: ReadableStream | null } = await client.GET(
+          "/anyMethod",
+          { parseAs: "stream" },
+        );
         expect(data instanceof Buffer).toBe(true);
       });
     });
diff --git a/packages/openapi-fetch/test/v7-beta.test.ts b/packages/openapi-fetch/test/v7-beta.test.ts
index 871bcd62c..542da7b86 100644
--- a/packages/openapi-fetch/test/v7-beta.test.ts
+++ b/packages/openapi-fetch/test/v7-beta.test.ts
@@ -578,23 +578,30 @@ describe("client", () => {
       it("text", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", { parseAs: "text" });
+        const { data }: { data?: string } = await client.GET("/anyMethod", {
+          parseAs: "text",
+        });
         expect(data).toBe("{}");
       });
 
       it("arrayBuffer", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", {
-          parseAs: "arrayBuffer",
-        });
+        const { data }: { data?: ArrayBuffer } = await client.GET(
+          "/anyMethod",
+          {
+            parseAs: "arrayBuffer",
+          },
+        );
         expect(data instanceof ArrayBuffer).toBe(true);
       });
 
       it("blob", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", { parseAs: "blob" });
+        const { data }: { data?: Blob } = await client.GET("/anyMethod", {
+          parseAs: "blob",
+        });
         // eslint-disable-next-line @typescript-eslint/no-explicit-any
         expect((data as any).constructor.name).toBe("Blob");
       });
@@ -602,7 +609,10 @@ describe("client", () => {
       it("stream", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data } = await client.GET("/anyMethod", { parseAs: "stream" });
+        const { data }: { data?: ReadableStream | null } = await client.GET(
+          "/anyMethod",
+          { parseAs: "stream" },
+        );
         expect(data instanceof Buffer).toBe(true);
       });
     });

From 7926e49ceebdbada179969a45273bb2d93470dbb Mon Sep 17 00:00:00 2001
From: hugeletters <ckuka71@gmail.com>
Date: Mon, 6 Nov 2023 02:00:13 +0100
Subject: [PATCH 3/4] stumped :|

---
 packages/openapi-fetch/src/index.d.ts | 98 +++++++++++++--------------
 1 file changed, 49 insertions(+), 49 deletions(-)

diff --git a/packages/openapi-fetch/src/index.d.ts b/packages/openapi-fetch/src/index.d.ts
index f90f61fa4..fca48e3c8 100644
--- a/packages/openapi-fetch/src/index.d.ts
+++ b/packages/openapi-fetch/src/index.d.ts
@@ -117,13 +117,12 @@ export default function createClient<Paths extends {}>(
     >
   >;
   /** Call a PUT endpoint */
-  PUT<P extends PathsWithMethod<Paths, "put">>(
+  PUT<
+    P extends PathsWithMethod<Paths, "put">,
+    O extends FetchOptions<FilterKeys<Paths[P], "put">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "put">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "put">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "put">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "put" extends infer T
@@ -132,17 +131,17 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a POST endpoint */
-  POST<P extends PathsWithMethod<Paths, "post">>(
+  POST<
+    P extends PathsWithMethod<Paths, "post">,
+    O extends FetchOptions<FilterKeys<Paths[P], "post">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "post">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "post">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "post">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "post" extends infer T
@@ -151,17 +150,17 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a DELETE endpoint */
-  DELETE<P extends PathsWithMethod<Paths, "delete">>(
+  DELETE<
+    P extends PathsWithMethod<Paths, "delete">,
+    O extends FetchOptions<FilterKeys<Paths[P], "delete">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "delete">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "delete">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "delete">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "delete" extends infer T
@@ -170,17 +169,17 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a OPTIONS endpoint */
-  OPTIONS<P extends PathsWithMethod<Paths, "options">>(
+  OPTIONS<
+    P extends PathsWithMethod<Paths, "options">,
+    O extends FetchOptions<FilterKeys<Paths[P], "options">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "options">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "options">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "options">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "options" extends infer T
@@ -189,17 +188,17 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a HEAD endpoint */
-  HEAD<P extends PathsWithMethod<Paths, "head">>(
+  HEAD<
+    P extends PathsWithMethod<Paths, "head">,
+    O extends FetchOptions<FilterKeys<Paths[P], "head">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "head">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "head">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "head">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "head" extends infer T
@@ -208,17 +207,17 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a PATCH endpoint */
-  PATCH<P extends PathsWithMethod<Paths, "patch">>(
+  PATCH<
+    P extends PathsWithMethod<Paths, "patch">,
+    O extends FetchOptions<FilterKeys<Paths[P], "patch">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "patch">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "patch">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "patch">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "patch" extends infer T
@@ -227,17 +226,17 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
   /** Call a TRACE endpoint */
-  TRACE<P extends PathsWithMethod<Paths, "trace">>(
+  TRACE<
+    P extends PathsWithMethod<Paths, "trace">,
+    O extends FetchOptions<FilterKeys<Paths[P], "trace">> = {},
+  >(
     url: P,
-    ...init: HasRequiredKeys<
-      FetchOptions<FilterKeys<Paths[P], "trace">>
-    > extends never
-      ? [(FetchOptions<FilterKeys<Paths[P], "trace">> | undefined)?]
-      : [FetchOptions<FilterKeys<Paths[P], "trace">>]
+    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
   ): Promise<
     FetchResponse<
       "trace" extends infer T
@@ -246,7 +245,8 @@ export default function createClient<Paths extends {}>(
             ? Paths[P][T]
             : unknown
           : never
-        : never
+        : never,
+      O
     >
   >;
 };

From 30f93837a90bae85a2a5dc02592616bf9cd84498 Mon Sep 17 00:00:00 2001
From: Drew Powers <drew@pow.rs>
Date: Sat, 18 Nov 2023 15:30:32 -0500
Subject: [PATCH 4/4] Add parseAs inference

---
 packages/openapi-fetch/src/index.d.ts     | 140 ++++++++--------------
 packages/openapi-fetch/src/index.js       |   5 +-
 packages/openapi-fetch/test/index.test.ts |  39 +++---
 3 files changed, 77 insertions(+), 107 deletions(-)

diff --git a/packages/openapi-fetch/src/index.d.ts b/packages/openapi-fetch/src/index.d.ts
index fca48e3c8..e5ee414b0 100644
--- a/packages/openapi-fetch/src/index.d.ts
+++ b/packages/openapi-fetch/src/index.d.ts
@@ -39,14 +39,14 @@ export type QuerySerializer<T> = (
 export type BodySerializer<T> = (body: OperationRequestBodyContent<T>) => any;
 
 export type ParseAs = "json" | "text" | "blob" | "arrayBuffer" | "stream";
-export type ParseAsResponse<T, K> = K extends ParseAs
-  ? {
-      json: T;
-      text: Awaited<ReturnType<Response["text"]>>;
-      blob: Awaited<ReturnType<Response["blob"]>>;
-      arrayBuffer: Awaited<ReturnType<Response["arrayBuffer"]>>;
-      stream: Response["body"];
-    }[K]
+export type ParseAsResponse<T, K extends ParseAs> = K extends "text"
+  ? Awaited<ReturnType<Response["text"]>>
+  : K extends "blob"
+  ? Awaited<ReturnType<Response["blob"]>>
+  : K extends "arrayBuffer"
+  ? Awaited<ReturnType<Response["arrayBuffer"]>>
+  : K extends "stream"
+  ? Awaited<ReturnType<Response["body"]>>
   : T;
 
 export interface DefaultParamsOption {
@@ -71,11 +71,19 @@ export type RequestBodyOption<T> = OperationRequestBodyContent<T> extends never
 
 export type FetchOptions<T> = RequestOptions<T> & Omit<RequestInit, "body">;
 
-export type FetchResponse<T, O extends FetchOptions<any>> =
+/** This type helper makes the 2nd function param required if params/requestBody are required; otherwise, optional */
+export type MaybeOptionalInit<
+  P extends {},
+  M extends keyof P,
+> = HasRequiredKeys<FetchOptions<FilterKeys<P, M>>> extends never
+  ? [(FetchOptions<FilterKeys<P, M>> | undefined)?]
+  : [FetchOptions<FilterKeys<P, M>>];
+
+export type FetchResponse<T, R extends ParseAs = "json"> =
   | {
       data: ParseAsResponse<
         FilterKeys<SuccessResponse<ResponseObjectMap<T>>, MediaType>,
-        O["parseAs"]
+        R
       >;
       error?: never;
       response: Response;
@@ -100,153 +108,105 @@ export default function createClient<Paths extends {}>(
   /** Call a GET endpoint */
   GET<
     P extends PathsWithMethod<Paths, "get">,
-    O extends FetchOptions<FilterKeys<Paths[P], "get">> = {},
+    I extends MaybeOptionalInit<Paths[P], "get">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "get" extends infer T
-        ? T extends "get"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["get"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a PUT endpoint */
   PUT<
     P extends PathsWithMethod<Paths, "put">,
-    O extends FetchOptions<FilterKeys<Paths[P], "put">> = {},
+    I extends MaybeOptionalInit<Paths[P], "put">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "put" extends infer T
-        ? T extends "put"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["put"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a POST endpoint */
   POST<
     P extends PathsWithMethod<Paths, "post">,
-    O extends FetchOptions<FilterKeys<Paths[P], "post">> = {},
+    I extends MaybeOptionalInit<Paths[P], "post">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "post" extends infer T
-        ? T extends "post"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["post"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a DELETE endpoint */
   DELETE<
     P extends PathsWithMethod<Paths, "delete">,
-    O extends FetchOptions<FilterKeys<Paths[P], "delete">> = {},
+    I extends MaybeOptionalInit<Paths[P], "delete">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "delete" extends infer T
-        ? T extends "delete"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["delete"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a OPTIONS endpoint */
   OPTIONS<
     P extends PathsWithMethod<Paths, "options">,
-    O extends FetchOptions<FilterKeys<Paths[P], "options">> = {},
+    I extends MaybeOptionalInit<Paths[P], "options">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "options" extends infer T
-        ? T extends "options"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["options"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a HEAD endpoint */
   HEAD<
     P extends PathsWithMethod<Paths, "head">,
-    O extends FetchOptions<FilterKeys<Paths[P], "head">> = {},
+    I extends MaybeOptionalInit<Paths[P], "head">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "head" extends infer T
-        ? T extends "head"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["head"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a PATCH endpoint */
   PATCH<
     P extends PathsWithMethod<Paths, "patch">,
-    O extends FetchOptions<FilterKeys<Paths[P], "patch">> = {},
+    I extends MaybeOptionalInit<Paths[P], "patch">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "patch" extends infer T
-        ? T extends "patch"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["patch"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
   /** Call a TRACE endpoint */
   TRACE<
     P extends PathsWithMethod<Paths, "trace">,
-    O extends FetchOptions<FilterKeys<Paths[P], "trace">> = {},
+    I extends MaybeOptionalInit<Paths[P], "trace">,
   >(
     url: P,
-    ...init: HasRequiredKeys<O> extends never ? [O?] : [O]
+    ...init: I
   ): Promise<
     FetchResponse<
-      "trace" extends infer T
-        ? T extends "trace"
-          ? T extends keyof Paths[P]
-            ? Paths[P][T]
-            : unknown
-          : never
-        : never,
-      O
+      Paths[P]["trace"],
+      I[0]["parseAs"] extends ParseAs ? I[O]["parseAs"] : "json"
     >
   >;
 };
diff --git a/packages/openapi-fetch/src/index.js b/packages/openapi-fetch/src/index.js
index 23e069fa5..acd39dcf4 100644
--- a/packages/openapi-fetch/src/index.js
+++ b/packages/openapi-fetch/src/index.js
@@ -21,8 +21,8 @@ export default function createClient(clientOptions) {
 
   /**
    * Per-request fetch (keeps settings created in createClient()
-   * @param {string} url
-   * @param {import('./index.js').FetchOptions} fetchOptions
+   * @param {T} url
+   * @param {import('./index.js').FetchOptions<T>} fetchOptions
    */
   async function coreFetch(url, fetchOptions) {
     const {
@@ -50,6 +50,7 @@ export default function createClient(clientOptions) {
     );
 
     // fetch!
+    /** @type {RequestInit} */
     const requestInit = {
       redirect: "follow",
       ...baseOptions,
diff --git a/packages/openapi-fetch/test/index.test.ts b/packages/openapi-fetch/test/index.test.ts
index 935e926b1..7125ac344 100644
--- a/packages/openapi-fetch/test/index.test.ts
+++ b/packages/openapi-fetch/test/index.test.ts
@@ -569,40 +569,49 @@ describe("client", () => {
       it("text", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data }: { data?: string } = await client.GET("/anyMethod", {
+        const { data, error } = await client.GET("/anyMethod", {
           parseAs: "text",
         });
-        expect(data).toBe("{}");
+        if (error) {
+          throw new Error(`parseAs text: error`);
+        }
+        expect(data.toLowerCase()).toBe("{}");
       });
 
       it("arrayBuffer", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data }: { data?: ArrayBuffer } = await client.GET(
-          "/anyMethod",
-          { parseAs: "arrayBuffer" },
-        );
-        expect(data instanceof ArrayBuffer).toBe(true);
+        const { data, error } = await client.GET("/anyMethod", {
+          parseAs: "arrayBuffer",
+        });
+        if (error) {
+          throw new Error(`parseAs arrayBuffer: error`);
+        }
+        expect(data.byteLength).toBe(true);
       });
 
       it("blob", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data }: { data?: Blob } = await client.GET("/anyMethod", {
+        const { data, error } = await client.GET("/anyMethod", {
           parseAs: "blob",
         });
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        expect((data as any).constructor.name).toBe("Blob");
+        if (error) {
+          throw new Error(`parseAs blob: error`);
+        }
+        expect((data as any).constructor.name).toBe("Blob"); // eslint-disable-line @typescript-eslint/no-explicit-any
       });
 
       it("stream", async () => {
         const client = createClient<paths>();
         mockFetchOnce({ status: 200, body: "{}" });
-        const { data }: { data?: ReadableStream | null } = await client.GET(
-          "/anyMethod",
-          { parseAs: "stream" },
-        );
-        expect(data instanceof Buffer).toBe(true);
+        const { data } = await client.GET("/anyMethod", {
+          parseAs: "stream",
+        });
+        if (!data) {
+          throw new Error(`parseAs stream: error`);
+        }
+        expect(data.byteLength).toBe(8);
       });
     });
   });