VOL-2087 reorganize and unit test arouterd

Change-Id: Iadacd1829095e8ffde306e5ebf164f4d67196a68
diff --git a/cmd/arouterd/arouterd_test.go b/cmd/arouterd/arouterd_test.go
new file mode 100644
index 0000000..e0f0ac4
--- /dev/null
+++ b/cmd/arouterd/arouterd_test.go
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2018-present Open Networking Foundation
+
+ * 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
+
+ * http://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 file implements an exit handler that tries to shut down all the
+// running servers before finally exiting. There are 2 triggers to this
+// clean exit thread: signals and an exit channel.
+
+package main
+
+import (
+	"github.com/stretchr/testify/assert"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+// run the function fp() and return its return value and stdout
+func CaptureStdout(fp func() int) (int, string, error) {
+	origStdout := os.Stdout
+
+	// log.Cleanup() will call Sync on sys.stdout, and that doesn't
+	// work on pipes. Instead of creating a pipe, write the output
+	// to a file, then read that file back in.
+	f, err := ioutil.TempFile("", "arouter.json")
+	if err != nil {
+		return 0, "", err
+	}
+
+	// Make sure the file is closed and deleted on exit
+	defer func() { f.Close(); os.Remove(f.Name()) }()
+
+	// reassign stdout to the file, ensure it will be restored on exit
+	os.Stdout = f
+	defer func() { os.Stdout = origStdout }()
+
+	status := fp()
+
+	// read back the contents of the tempfile
+	_, err = f.Seek(0, 0)
+	if err != nil {
+		return 0, "", err
+	}
+	out := make([]byte, 16384)
+	numRead, err := f.Read(out)
+	if err != nil {
+		return 0, "", err
+	}
+
+	return status, string(out[:numRead]), nil
+}
+
+// Test output of "--version" command
+func TestStartupVersionOnly(t *testing.T) {
+	oldArgs := os.Args
+	defer func() { os.Args = oldArgs }()
+
+	os.Args = []string{os.Args[0], "--version"}
+
+	status, s, err := CaptureStdout(startup)
+	assert.Nil(t, err)
+
+	assert.Equal(t, 0, status)
+
+	expected := `VOLTHA API Server (afrouterd)
+  Version:      unknown-version
+  GoVersion:    unknown-goversion
+  VCS Ref:      unknown-vcsref
+  VCS Dirty:    unknown-vcsdirty
+  Built:        unknown-buildtime
+  OS/Arch:      unknown-os/unknown-arch
+
+`
+	assert.Equal(t, expected, s)
+}
+
+// An unknown command-line option should produce an error
+func TestStartupBadCommandLine(t *testing.T) {
+	oldArgs := os.Args
+	defer func() { os.Args = oldArgs }()
+
+	os.Args = []string{os.Args[0], "--badoption"}
+
+	status, s, err := CaptureStdout(startup)
+	assert.Nil(t, err)
+
+	assert.Equal(t, 1, status)
+
+	assert.Contains(t, s, "Error: flag provided but not defined: -badoption")
+}