Add unit test case for empty list

pkg/kubectl/cmd/get/get_test.go

@@ -560,6 +560,15 @@ func TestRuntimeSorter(t *testing.T) {
 		expect      string
 		expectError string
 	}{
+		{
+			name:  "ensure sorter works with an empty object list",
+			field: "metadata.name",
+			objs:  []runtime.Object{},
+			op: func(sorter *RuntimeSorter, objs []runtime.Object, out io.Writer) error {
+				return nil
+			},
+			expect: "",
+		},
 		{
 			name:  "ensure sorter returns original position",
 			field: "metadata.name",