allow body to be a binary ReadableStream

.changeset/wet-hairs-wink.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+Allow body to be a binary ReadableStream

packages/kit/src/runtime/server/endpoint.js

@@ -100,9 +100,12 @@ export async function render_endpoint(event, mod) {
 
 	const type = headers.get('content-type');
 
-	if (!is_text(type) && !(body instanceof Uint8Array || is_string(body))) {
+	if (
+		!is_text(type) &&
+		!(body instanceof Uint8Array || body instanceof ReadableStream || is_string(body))
+	) {
 		return error(
-			`${preface}: body must be an instance of string or Uint8Array if content-type is not a supported textual content-type`
+			`${preface}: body must be an instance of string, Uint8Array or ReadableStream if content-type is not a supported textual content-type`
 		);
 	}
 

packages/kit/test/apps/basics/src/routes/endpoint-output/stream.js

@@ -0,0 +1,14 @@
+/** @type {import('@sveltejs/kit').RequestHandler} */
+export function get() {
+	return {
+		headers: {
+			'content-type': 'application/octet-stream'
+		},
+		body: new ReadableStream({
+			start: (controller) => {
+				controller.enqueue(new Uint8Array([1, 2, 3]));
+				controller.close();
+			}
+		})
+	};
+}

packages/kit/test/apps/basics/test/test.js

@@ -769,6 +769,12 @@ test.describe('Endpoints', () => {
 		const r2 = await request.get('/endpoint-output/simple/__data.json');
 		expect(r2.status()).toBe(404);
 	});
+
+	test('body can be a binary ReadableStream', async ({ request }) => {
+		const response = await request.get('/endpoint-output/stream');
+		const body = await response.body();
+		expect(Array.from(body)).toEqual([1, 2, 3]);
+	});
 });
 
 test.describe('Encoded paths', () => {