Finder: support DistributedVirtualSwitch traversal

While the native vSphere SearchIndex and ContainerView APIs don't support
inventory paths with this structure, it is useful for use with NSXt3 where
portgroup may not be unique within the same network inventory folder.

govc/test/import.bats

@@ -178,6 +178,11 @@ load test_helper
   run govc import.ovf -options - "$ovf" <<<"$options"
   assert_failure # 2 networks have the same name
 
+  options=$(jq ".NetworkMapping[].Network = \"DVS0/NSX-dvpg\"" <<<"$spec")
+
+  run govc import.ovf -name ttylinux2 -options - "$ovf" <<<"$options"
+  assert_success # switch_name/portgroup_name is unique
+
   switch=$(govc find -i network -name DVS0)
   id=$(govc find -i network -config.distributedVirtualSwitch "$switch" -name NSX-dvpg)
   options=$(jq ".NetworkMapping[].Network = \"$id\"" <<<"$spec")

govc/test/network.bats

@@ -38,6 +38,22 @@ load test_helper
 
   run govc device.remove -vm $vm $eth0
   assert_failure "govc: device '$eth0' not found"
+
+  # Test PG's with the same name
+  run govc dvs.create DVS1 # DVS0 already exists
+  assert_success
+
+  run govc dvs.portgroup.add -dvs DVS0 -type ephemeral NSX-dvpg
+  assert_success
+
+  run govc dvs.portgroup.add -dvs DVS1 -type ephemeral NSX-dvpg
+  assert_success
+
+  run govc vm.network.add -vm $vm -net NSX-dvpg
+  assert_failure # resolves to multiple networks
+
+  run govc vm.network.add -vm $vm -net DVS0/NSX-dvpg
+  assert_success # switch_name/portgroup_name is unique
 }
 
 @test "network change backing" {

govc/vm/network/add.go

@@ -47,6 +47,7 @@ func (cmd *add) Description() string {
 
 Examples:
   govc vm.network.add -vm $vm -net "VM Network" -net.adapter e1000e
+  govc vm.network.add -vm $vm -net SwitchName/PortgroupName
   govc device.info -vm $vm ethernet-*`
 }
 

list/lister.go

@@ -165,6 +165,8 @@ func (l Lister) List(ctx context.Context) ([]Element, error) {
 		return l.ListHostSystem(ctx)
 	case "VirtualApp":
 		return l.ListVirtualApp(ctx)
+	case "VmwareDistributedVirtualSwitch", "DistributedVirtualSwitch":
+		return l.ListDistributedVirtualSwitch(ctx)
 	default:
 		return nil, fmt.Errorf("cannot traverse type " + l.Reference.Type)
 	}
@@ -497,6 +499,69 @@ func (l Lister) ListHostSystem(ctx context.Context) ([]Element, error) {
 	return es, nil
 }
 
+func (l Lister) ListDistributedVirtualSwitch(ctx context.Context) ([]Element, error) {
+	ospec := types.ObjectSpec{
+		Obj:  l.Reference,
+		Skip: types.NewBool(true),
+	}
+
+	fields := []string{
+		"portgroup",
+	}
+
+	for _, f := range fields {
+		tspec := types.TraversalSpec{
+			Path: f,
+			Skip: types.NewBool(false),
+			Type: "DistributedVirtualSwitch",
+		}
+
+		ospec.SelectSet = append(ospec.SelectSet, &tspec)
+	}
+
+	childTypes := []string{
+		"DistributedVirtualPortgroup",
+	}
+
+	var pspecs []types.PropertySpec
+	for _, t := range childTypes {
+		pspec := types.PropertySpec{
+			Type: t,
+		}
+
+		if l.All {
+			pspec.All = types.NewBool(true)
+		} else {
+			pspec.PathSet = []string{"name"}
+		}
+
+		pspecs = append(pspecs, pspec)
+	}
+
+	req := types.RetrieveProperties{
+		SpecSet: []types.PropertyFilterSpec{
+			{
+				ObjectSet: []types.ObjectSpec{ospec},
+				PropSet:   pspecs,
+			},
+		},
+	}
+
+	var dst []interface{}
+
+	err := l.retrieveProperties(ctx, req, &dst)
+	if err != nil {
+		return nil, err
+	}
+
+	es := []Element{}
+	for _, v := range dst {
+		es = append(es, ToElement(v.(mo.Reference), l.Prefix))
+	}
+
+	return es, nil
+}
+
 func (l Lister) ListVirtualApp(ctx context.Context) ([]Element, error) {
 	ospec := types.ObjectSpec{
 		Obj:  l.Reference,