Removed hard coded ports from thttpclient_standalone.nim. (#18374)

Co-authored-by: Dominik Picheta <dominikpicheta@googlemail.com>
Co-authored-by: Mark Pointing <mark@futurepoint.com.au>
Co-authored-by: Andreas Rumpf <rumpf_a@web.de>
Co-authored-by: Timothee Cour <timothee.cour2@gmail.com>

tests/stdlib/thttpclient_standalone.nim

@@ -2,29 +2,37 @@ discard """
   cmd: "nim c --threads:on $file"
 """
 
-import asynchttpserver, httpclient, asyncdispatch, strutils
+import asynchttpserver, httpclient, asyncdispatch, strutils, net
 
 block: # bug #16436
-  proc startServer() {.async.} =
+  proc startServer(): AsyncHttpServer =
+    result = newAsyncHttpServer()
+    result.listen(Port(0))
+
+  proc processRequest(server: AsyncHttpServer) {.async.} =
     proc cb(req: Request) {.async.} =
       let headers = { "Content-length": "15"} # Provide invalid content-length
       await req.respond(Http200, "Hello World", headers.newHttpHeaders())
 
-    var server = newAsyncHttpServer()
-    await server.serve(Port(5555), cb)
+    await server.acceptRequest(cb)
 
-  proc runClient() {.async.} =
+  proc runClient(port: Port) {.async.} =
     let c = newAsyncHttpClient(headers = {"Connection": "close"}.newHttpHeaders)
-    let r = await c.getContent("http://127.0.0.1:5555")
+    discard await c.getContent("http://127.0.0.1:" & $port)
     doAssert false, "should fail earlier"
 
-  asyncCheck startServer()
+  let server = startServer()
+  asyncCheck processRequest(server)
+  let port = server.getPort()
   doAssertRaises(ProtocolError):
-    waitFor runClient()
+    waitFor runClient(port)
 
 block: # bug #14794 (And test for presence of content-length header when using postContent)
-  proc startServer() {.async.} =
-    var killServer = false
+  proc startServer(): AsyncHttpServer =
+    result = newAsyncHttpServer()
+    result.listen(Port(0))
+
+  proc runServer(server: AsyncHttpServer) {.async.} =
     proc cb(req: Request) {.async.} =
       doAssert(req.body.endsWith(httpNewLine), "Multipart body does not end with a newline.")
       # this next line is probably not required because asynchttpserver does not call
@@ -32,23 +40,18 @@ block: # bug #14794 (And test for presence of content-length header when using p
       # Error: unhandled exception: 411 Length Required
       # Added for good measure in case the server becomes more permissive.
       doAssert(req.headers.hasKey("content-length"), "Content-Length header is not present.")
-      killServer = true
       asyncCheck req.respond(Http200, "OK")
 
-    var server = newAsyncHttpServer()
-    server.listen(Port(5556))
-    while not killServer:
-      if server.shouldAcceptRequest():
-        await server.acceptRequest(cb)
-      else:
-        poll()
+    await server.acceptRequest(cb)
 
-  proc runClient() {.async.} =
+  proc runClient(port: Port) {.async.} =
     let c = newAsyncHttpClient()
-    var data = newMultipartData()
+    let data = newMultipartData()
     data.add("file.txt", "This is intended to be an example text file.\r\nThis would be the second line.\r\n")
-    let r = await c.postContent("http://127.0.0.1:5556", multipart = data)
+    discard await c.postContent("http://127.0.0.1:" & $port, multipart = data)
     c.close()
 
-  asyncCheck startServer()
-  waitFor runClient()
+  let server = startServer()
+  let port = server.getPort()
+  asyncCheck runServer(server)
+  waitFor runClient(port)