First piece of validation

I'm adding pieces incrementally to make sure we get full testing of each
piece.

Make syncLoop() private

pkg/api/validation_test.go

@@ -0,0 +1,50 @@
+/*
+Copyright 2014 Google Inc. All rights reserved.
+
+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.
+*/
+
+package api
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestValidateManifest(t *testing.T) {
+	successCases := []ContainerManifest{
+		{Version: "v1beta1", ID: "abc"},
+		{Version: "v1beta1", ID: "123"},
+		{Version: "v1beta1", ID: "abc.123.do-re-mi"},
+	}
+	for _, manifest := range successCases {
+		err := ValidateManifest(&manifest)
+		if err != nil {
+			t.Errorf("expected success: %v", err)
+		}
+	}
+
+	errorCases := map[string]ContainerManifest{
+		"empty version":          {Version: "", ID: "abc"},
+		"invalid version":        {Version: "bogus", ID: "abc"},
+		"zero-length id":         {Version: "v1beta1", ID: ""},
+		"id > 255 characters":    {Version: "v1beta1", ID: strings.Repeat("a", 256)},
+		"id not a DNS subdomain": {Version: "v1beta1", ID: "a.b.c."},
+	}
+	for k, v := range errorCases {
+		err := ValidateManifest(&v)
+		if err == nil {
+			t.Errorf("expected failure for %s", k)
+		}
+	}
+}