fix(test): use explicit dispatcher in content-encoding tests

The first describe block used the global agent, leaving pooled connections alive after server.closeAllConnections() sent RST. On macOS, the async RST delivery could surface as ECONNRESET in the next describe block's fetch call. Give each block its own Client and await cleanup to eliminate the race.

Signed-off-by: Sam Mayer <sam.mayer@defenseunicorns.com>

Author: samayer12

test/fetch/encoding.js

@@ -10,6 +10,7 @@ describe('content-encoding handling', () => {
   const zstdText = Buffer.from('KLUv/QBYaQAASGVsbG8sIFdvcmxkIQ==', 'base64')
 
   let server
+  let client
   before(async () => {
     server = createServer({
       noDelay: true
@@ -47,16 +48,19 @@ describe('content-encoding handling', () => {
       }
     })
     await once(server.listen(0), 'listening')
+    client = new Client(`http://localhost:${server.address().port}`)
   })
 
-  after(() => {
+  after(async () => {
+    await client.close()
     server.closeAllConnections?.()
     server.close()
+    await once(server, 'close')
   })
 
   test('content-encoding header', async (t) => {
     const response = await fetch(`http://localhost:${server.address().port}`, {
-      keepalive: false,
+      dispatcher: client,
       headers: { 'accept-encoding': 'deflate, gzip' }
     })
 
@@ -67,7 +71,7 @@ describe('content-encoding handling', () => {
 
   test('content-encoding header is case-iNsENsITIve', async (t) => {
     const response = await fetch(`http://localhost:${server.address().port}`, {
-      keepalive: false,
+      dispatcher: client,
       headers: { 'accept-encoding': 'DeFlAtE, GzIp' }
     })
 
@@ -80,7 +84,7 @@ describe('content-encoding handling', () => {
     { skip: typeof require('node:zlib').createZstdDecompress !== 'function' },
     async (t) => {
       const response = await fetch(`http://localhost:${server.address().port}`, {
-        keepalive: false,
+        dispatcher: client,
         headers: { 'accept-encoding': 'zstd' }
       })