fix: ensure that compress stream stays open (#375)

Author: fabianszabo

index.js

@@ -447,7 +447,7 @@ function compress (params) {
 
     stream = zipStream(params.compressStream, encoding)
     pump(payload, stream, onEnd.bind(this))
-    this.send(stream)
+    return this.send(stream)
   }
 }
 

test/regression/issue-350.test.js

@@ -0,0 +1,43 @@
+'use strict'
+
+const { test } = require('node:test')
+const zlib = require('node:zlib')
+const Fastify = require('fastify')
+const fastifyCompress = require('../..')
+
+const largeJsonString = JSON.stringify({
+  text: 'Lorem ipsum dolor sit amet. '.repeat(2048),
+})
+
+async function routes (fastify) {
+  fastify.route({
+    method: 'GET',
+    url: '/api/compress-test',
+    handler: async function (_request, reply) {
+      reply.type('application/json')
+      return reply.compress(largeJsonString)
+    }
+  })
+}
+
+test('should compress large payload without premature close', async (t) => {
+  const fastify = Fastify()
+  await fastify.register(fastifyCompress, { encodings: ['gzip'], global: true })
+  await fastify.register(routes)
+
+  const response = await fastify.inject({
+    url: '/api/compress-test',
+    method: 'GET',
+    headers: { 'accept-encoding': 'gzip' }
+  })
+
+  t.assert.equal(response.statusCode, 200)
+  t.assert.equal(response.headers['content-encoding'], 'gzip')
+  t.assert.ok(
+    response.rawPayload.length > 0,
+    `Expected compressed response body, got ${response.rawPayload.length} bytes`
+  )
+
+  const decompressed = zlib.gunzipSync(response.rawPayload)
+  t.assert.equal(decompressed.toString('utf-8'), largeJsonString)
+})