Add mock server outline and test (#19)

Author: polinasok

cmd/mockserver/main.go

@@ -0,0 +1,32 @@
+// Copyright 2019 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// This starts a mock DAP server that runs indefinitely, accepts DAP
+// requests and responds with dummy or error responses.
+
+package main
+
+import (
+	"flag"
+	"log"
+)
+
+func main() {
+	port := flag.String("port", "54321", "TCP port to listen on")
+	flag.Parse()
+	err := server(*port)
+	if err != nil {
+		log.Fatal("Could not start server: ", err)
+	}
+}