fix: end response stream on mocked 204 responses

src/middleware.ts

@@ -68,6 +68,8 @@ export function createMiddleware(
               mockedResponse.body as ReadableStream,
             )
             stream.pipe(res)
+          } else {
+            res.end()
           }
         },
         onPassthroughResponse() {

test/middleware.test.ts

@@ -11,6 +11,10 @@ const httpServer = new HttpServer((app) => {
   // so that any matching request is resolved from the mocks.
   app.use(
     createMiddleware(
+      http.post('/users', () => {
+        return new HttpResponse(null, { status: 204 })
+      }),
+
       http.get('/user', () => {
         return HttpResponse.json(
           { firstName: 'John' },
@@ -53,6 +57,14 @@ it('returns the mocked response when requesting the middleware', async () => {
   }
 })
 
+it('returns the mocked 204 with empty body', async () => {
+  const res = await fetch(httpServer.http.url('/users'), { method: 'POST' })
+
+  expect(res.status).toEqual(204)
+  expect(res.ok).toBeTruthy()
+  expect(res.bodyUsed).toBeFalsy()
+})
+
 it('returns the original response given no matching request handler', async () => {
   const res = await fetch(httpServer.http.url('/book'))
   const text = await res.text()