Make sure all ports are allocated at once to minimize clashes

cmd/stellar-rpc/internal/integrationtest/infrastructure/test.go

@@ -477,10 +477,11 @@ func (i *Test) spawnRPCDaemon() {
 	// We need to dynamically allocate port numbers since tests run in parallel.
 	// Unfortunately this isn't completely clash-free,
 	// but there is no way to tell core to allocate the port dynamically
-	i.testPorts.captiveCorePort = getFreeTCPPort(i.t)
+	freePorts := getFreeTCPPorts(i.t, 3)
+	i.testPorts.captiveCorePort = freePorts[0]
 	if i.enableCoreHTTPQueryServer {
-		i.testPorts.captiveCoreHTTPQueryPort = getFreeTCPPort(i.t)
-		i.testPorts.captiveCoreHTTPPort = getFreeTCPPort(i.t)
+		i.testPorts.captiveCoreHTTPQueryPort = freePorts[1]
+		i.testPorts.captiveCoreHTTPPort = freePorts[2]
 	}
 	i.generateCaptiveCoreCfgForDaemon()
 	rpcCfg := i.getRPConfigForDaemon()

cmd/stellar-rpc/internal/integrationtest/infrastructure/util.go

@@ -16,15 +16,19 @@ func GetCurrentDirectory() string {
 	return filepath.Dir(currentFilename)
 }
 
-func getFreeTCPPort(t require.TestingT) uint16 {
-	var a *net.TCPAddr
-	a, err := net.ResolveTCPAddr("tcp", "localhost:0")
-	require.NoError(t, err)
-	var l *net.TCPListener
-	l, err = net.ListenTCP("tcp", a)
-	require.NoError(t, err)
-	defer l.Close()
-	return uint16(l.Addr().(*net.TCPAddr).Port)
+func getFreeTCPPorts(t require.TestingT, count int) []uint16 {
+	result := make([]uint16, count)
+	for i := range count {
+		var a *net.TCPAddr
+		a, err := net.ResolveTCPAddr("tcp", "localhost:0")
+		require.NoError(t, err)
+		var l *net.TCPListener
+		l, err = net.ListenTCP("tcp", a)
+		require.NoError(t, err)
+		defer l.Close()
+		result[i] = uint16(l.Addr().(*net.TCPAddr).Port)
+	}
+	return result
 }
 
 func CreateTransactionParams(account txnbuild.Account, op txnbuild.Operation) txnbuild.TransactionParams {