Allow injecting fetch into TypeScript clients

internal/tsemit/templates/api.ts.gotmpl

@@ -11,6 +11,7 @@ export type FetchInterceptorChain = {
 
 export type ClientOptions = {
     baseURL?: string;
+    fetch?: typeof globalThis.fetch;
     interceptors?: FetchInterceptor[];
     responseTimeoutMs?: number;
     sseIdleTimeoutMs?: number;
@@ -489,6 +490,7 @@ async function* parseEventStream<T>(
 async function runInterceptors(
     request: Request,
     interceptors: FetchInterceptor[],
+    fetch: typeof globalThis.fetch,
 ): Promise<Response> {
     async function dispatch(index: number, nextRequest: Request): Promise<Response> {
         const interceptor = interceptors[index];
@@ -511,6 +513,7 @@ async function runInterceptors(
 
 {{end}}export class DefaultApi {
     private baseURL: string;
+    private fetch: typeof globalThis.fetch;
     private interceptors: FetchInterceptor[];
     private responseTimeoutMs: number | undefined;
 {{if .HasSSE}}
@@ -522,6 +525,7 @@ async function runInterceptors(
 
     constructor(options: ClientOptions = {}) {
         this.baseURL = options.baseURL ?? '';
+        this.fetch = options.fetch ?? globalThis.fetch;
         this.interceptors = options.interceptors ?? [];
         this.responseTimeoutMs = configuredTimeout(
             options,
@@ -559,7 +563,7 @@ async function runInterceptors(
         };
         try {
             return {
-                response: await runInterceptors(finalRequest, this.interceptors),
+                response: await runInterceptors(finalRequest, this.interceptors, this.fetch),
                 timeout: timedRequest,
                 request: finalRequest,
             };

oasmith_test.go

@@ -300,6 +300,63 @@ import assert from "node:assert/strict"
 import { DefaultApi, type FetchInterceptor } from "./api.ts"
 
 void describe("api interceptors", () => {
+  void test("passes the final intercepted request to a custom fetch", async () => {
+    let fetchedRequest: Request | undefined
+    const api = new DefaultApi({
+      baseURL: "https://example.test",
+      fetch: async request => {
+        assert.ok(request instanceof Request)
+        fetchedRequest = request
+        return new Response("[]")
+      },
+      interceptors: [
+        async chain => {
+          const headers = new Headers(chain.request.headers)
+          headers.set("traceparent", "custom-trace")
+          return await chain.proceed(new Request(chain.request, { headers }))
+        },
+      ],
+    })
+
+    await api.listTestEmails()
+
+    assert.ok(fetchedRequest instanceof Request)
+    assert.equal(fetchedRequest.headers.get("traceparent"), "custom-trace")
+  })
+
+  void test("uses custom fetch for SSE reconnects", async () => {
+    let fetchCalls = 0
+    const encoder = new TextEncoder()
+    const api = new DefaultApi({
+      baseURL: "https://example.test",
+      fetch: async () => {
+        fetchCalls += 1
+        return new Response(new ReadableStream({
+          start(controller) {
+            controller.enqueue(encoder.encode("data: {}\n\n"))
+            controller.close()
+          },
+        }), { headers: { "content-type": "text/event-stream" } })
+      },
+      responseTimeoutMs: 0,
+      sseMaxRetries: 1,
+      sseReconnectBaseDelayMs: 0,
+    })
+
+    const response = await api.episodeProcessingEventsResult({
+      episodeId: "episode_1",
+      showId: "show_1",
+      teamId: "team_1",
+    })
+    assert.equal(response.status, 200)
+    if (response.status !== 200) throw new Error("unexpected status")
+    const iterator = response.body[Symbol.asyncIterator]()
+    assert.equal((await iterator.next()).done, false)
+    assert.equal((await iterator.next()).done, false)
+    assert.equal(fetchCalls, 2)
+    await iterator.return?.()
+  })
+
   void test("run in order and allow repeated proceed", async () => {
     const events: Array<string> = []
     const interceptors: Array<FetchInterceptor> = [

testdata/golden/config-typescript/api.ts

@@ -9,6 +9,7 @@ export type FetchInterceptorChain = {
 
 export type ClientOptions = {
   baseURL?: string
+  fetch?: typeof globalThis.fetch
   interceptors?: FetchInterceptor[]
   responseTimeoutMs?: number
   sseIdleTimeoutMs?: number
@@ -99,6 +100,7 @@ function responseTimeout(
 async function runInterceptors(
   request: Request,
   interceptors: FetchInterceptor[],
+  fetch: typeof globalThis.fetch,
 ): Promise<Response> {
   async function dispatch(
     index: number,
@@ -120,11 +122,13 @@ async function runInterceptors(
 
 export class DefaultApi {
   private baseURL: string
+  private fetch: typeof globalThis.fetch
   private interceptors: FetchInterceptor[]
   private responseTimeoutMs: number | undefined
 
   constructor(options: ClientOptions = {}) {
     this.baseURL = options.baseURL ?? ""
+    this.fetch = options.fetch ?? globalThis.fetch
     this.interceptors = options.interceptors ?? []
     this.responseTimeoutMs = configuredTimeout(
       options,
@@ -157,7 +161,11 @@ export class DefaultApi {
     }
     try {
       return {
-        response: await runInterceptors(finalRequest, this.interceptors),
+        response: await runInterceptors(
+          finalRequest,
+          this.interceptors,
+          this.fetch,
+        ),
         timeout: timedRequest,
         request: finalRequest,
       }

testdata/golden/private-typescript/api.ts

@@ -50,6 +50,7 @@ export type FetchInterceptorChain = {
 
 export type ClientOptions = {
   baseURL?: string
+  fetch?: typeof globalThis.fetch
   interceptors?: FetchInterceptor[]
   responseTimeoutMs?: number
   sseIdleTimeoutMs?: number
@@ -555,6 +556,7 @@ async function* parseEventStream<T>(
 async function runInterceptors(
   request: Request,
   interceptors: FetchInterceptor[],
+  fetch: typeof globalThis.fetch,
 ): Promise<Response> {
   async function dispatch(
     index: number,
@@ -686,6 +688,7 @@ export interface RenderShowRSSFeedRequest {
 
 export class DefaultApi {
   private baseURL: string
+  private fetch: typeof globalThis.fetch
   private interceptors: FetchInterceptor[]
   private responseTimeoutMs: number | undefined
 
@@ -696,6 +699,7 @@ export class DefaultApi {
 
   constructor(options: ClientOptions = {}) {
     this.baseURL = options.baseURL ?? ""
+    this.fetch = options.fetch ?? globalThis.fetch
     this.interceptors = options.interceptors ?? []
     this.responseTimeoutMs = configuredTimeout(
       options,
@@ -736,7 +740,11 @@ export class DefaultApi {
     }
     try {
       return {
-        response: await runInterceptors(finalRequest, this.interceptors),
+        response: await runInterceptors(
+          finalRequest,
+          this.interceptors,
+          this.fetch,
+        ),
         timeout: timedRequest,
         request: finalRequest,
       }