Add UT for pkg/discovery

Signed-off-by: Ming <mqiu@vmware.com>

pkg/test/fake_mapper.go

@@ -19,13 +19,15 @@ package test
 import (
 	"github.com/pkg/errors"
 	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 )
 
 type FakeMapper struct {
 	meta.RESTMapper
-	AutoReturnResource bool
-	Resources          map[schema.GroupVersionResource]schema.GroupVersionResource
+	AutoReturnResource   bool
+	Resources            map[schema.GroupVersionResource]schema.GroupVersionResource
+	KindToPluralResource map[schema.GroupVersionKind]schema.GroupVersionResource
 }
 
 func (m *FakeMapper) ResourceFor(input schema.GroupVersionResource) (schema.GroupVersionResource, error) {
@@ -56,3 +58,36 @@ func (m *FakeMapper) ResourceFor(input schema.GroupVersionResource) (schema.Grou
 
 	return schema.GroupVersionResource{}, errors.Errorf("invalid resource %q", input.String())
 }
+
+func (m *FakeMapper) RESTMapping(gk schema.GroupKind, versions ...string) (*meta.RESTMapping, error) {
+	potentialGVK := make([]schema.GroupVersionKind, 0)
+	// Pick an appropriate version
+	for _, version := range versions {
+		if len(version) == 0 || version == runtime.APIVersionInternal {
+			continue
+		}
+		currGVK := gk.WithVersion(version)
+		if _, ok := m.KindToPluralResource[currGVK]; ok {
+			potentialGVK = append(potentialGVK, currGVK)
+			break
+		}
+	}
+	if len(potentialGVK) == 0 {
+		return nil, &meta.NoKindMatchError{GroupKind: gk, SearchedVersions: versions}
+	}
+
+	for _, gvk := range potentialGVK {
+		//Ensure we have a REST mapping
+		res, ok := m.KindToPluralResource[gvk]
+		if !ok {
+			continue
+		}
+
+		return &meta.RESTMapping{
+			Resource:         res,
+			GroupVersionKind: gvk,
+			Scope:            meta.RESTScopeNamespace,
+		}, nil
+	}
+	return nil, &meta.NoResourceMatchError{PartialResource: schema.GroupVersionResource{Group: gk.Group, Resource: gk.Kind}}
+}