Refactor GlusterFS PV spec.

This patch introduces glusterfsPersistentVolumeSource addition
to glusterfsVolumeSource. All fields remains same as glusterfsVolumeSource
with an addition of a new field
called `EndpointsNamespace` to define namespace of endpoint in the
spec.

Signed-off-by: Humble Chirammal <hchiramm@redhat.com>

pkg/apis/core/validation/validation_test.go

@@ -1774,6 +1774,60 @@ func TestValidateGlusterfs(t *testing.T) {
 	}
 }
 
+func TestValidateGlusterfsPersistentVolumeSource(t *testing.T) {
+	var epNs *string
+	namespace := ""
+	epNs = &namespace
+
+	testCases := []struct {
+		name     string
+		gfs      *core.GlusterfsPersistentVolumeSource
+		errtype  field.ErrorType
+		errfield string
+	}{
+		{
+			name:     "missing endpointname",
+			gfs:      &core.GlusterfsPersistentVolumeSource{EndpointsName: "", Path: "/tmp"},
+			errtype:  field.ErrorTypeRequired,
+			errfield: "endpoints",
+		},
+		{
+			name:     "missing path",
+			gfs:      &core.GlusterfsPersistentVolumeSource{EndpointsName: "my-endpoint", Path: ""},
+			errtype:  field.ErrorTypeRequired,
+			errfield: "path",
+		},
+		{
+			name:     "non null endpointnamespace with empty string",
+			gfs:      &core.GlusterfsPersistentVolumeSource{EndpointsName: "my-endpoint", Path: "/tmp", EndpointsNamespace: epNs},
+			errtype:  field.ErrorTypeInvalid,
+			errfield: "endpointsNamespace",
+		},
+		{
+			name:     "missing endpointname and path",
+			gfs:      &core.GlusterfsPersistentVolumeSource{EndpointsName: "", Path: ""},
+			errtype:  field.ErrorTypeRequired,
+			errfield: "endpoints",
+		},
+	}
+
+	for i, tc := range testCases {
+		errs := validateGlusterfsPersistentVolumeSource(tc.gfs, field.NewPath("field"))
+
+		if len(errs) > 0 && tc.errtype == "" {
+			t.Errorf("[%d: %q] unexpected error(s): %v", i, tc.name, errs)
+		} else if len(errs) == 0 && tc.errtype != "" {
+			t.Errorf("[%d: %q] expected error type %v", i, tc.name, tc.errtype)
+		} else if len(errs) >= 1 {
+			if errs[0].Type != tc.errtype {
+				t.Errorf("[%d: %q] expected error type %v, got %v", i, tc.name, tc.errtype, errs[0].Type)
+			} else if !strings.HasSuffix(errs[0].Field, "."+tc.errfield) {
+				t.Errorf("[%d: %q] expected error on field %q, got %q", i, tc.name, tc.errfield, errs[0].Field)
+			}
+		}
+	}
+}
+
 func TestValidateCSIVolumeSource(t *testing.T) {
 	testCases := []struct {
 		name     string