Add test keep the query params on proxy without params in prefix

test/test.js

@@ -47,6 +47,10 @@ async function run () {
     return `this is "variable-api" endpoint with id ${request.params.id} and query params ${JSON.stringify(request.query)}`
   })
 
+  origin.get('/api/endpoint-with-query', async (request, reply) => {
+    return `this is "api" endpoint with query params ${JSON.stringify(request.query)}`
+  })
+
   origin.get('/timeout', async (request, reply) => {
     await new Promise((resolve) => setTimeout(resolve, 600))
     return 'this is never received'
@@ -917,6 +921,28 @@ async function run () {
     const queryParams = JSON.stringify(qs.parse('foo=bar&foo=baz&abc=qux'))
     t.equal(firstProxyPrefix.body, `this is "variable-api" endpoint with id 123 and query params ${queryParams}`)
   })
+
+  test('keep the query params on proxy without params in prefix', { only: true }, async t => {
+    const proxyServer = Fastify()
+
+    proxyServer.register(proxy, {
+      upstream: `http://localhost:${origin.server.address().port}`,
+      prefix: '/api/endpoint',
+      rewritePrefix: '/api/endpoint-with-query'
+    })
+
+    await proxyServer.listen({ port: 0 })
+
+    t.teardown(() => {
+      proxyServer.close()
+    })
+
+    const firstProxyPrefix = await got(
+      `http://localhost:${proxyServer.server.address().port}/api/endpoint?foo=bar&foo=baz&abc=qux`
+    )
+    const queryParams = JSON.stringify(qs.parse('foo=bar&foo=baz&abc=qux'))
+    t.equal(firstProxyPrefix.body, `this is "api" endpoint with query params ${queryParams}`)
+  })
 }
 
 run()