client-go tpr example: round trip external tpr types

staging/src/k8s.io/apimachinery/pkg/api/testing/roundtrip.go

@@ -242,8 +242,15 @@ func roundTripOfExternalType(t *testing.T, scheme *runtime.Scheme, codecFactory
 
 // roundTrip applies a single round-trip test to the given runtime object
 // using the given codec.  The round-trip test ensures that an object can be
-// deep-copied and converted from internal -> versioned -> internal without
-// loss of data.
+// deep-copied, converted, marshaled and back without loss of data.
+//
+// For internal types this means
+//
+//   internal -> external -> json/protobuf -> external -> internal.
+//
+// For external types this means
+//
+//   external -> json/protobuf -> external.
 func roundTrip(t *testing.T, scheme *runtime.Scheme, codec runtime.Codec, object runtime.Object) {
 	printer := spew.ConfigState{DisableMethods: true}
 	original := object

staging/src/k8s.io/client-go/examples/third-party-resources/apis/tpr/v1/types_test.go

@@ -17,8 +17,15 @@ limitations under the License.
 package v1
 
 import (
+	"math/rand"
+	"testing"
+
+	"github.com/google/gofuzz"
+
+	apitesting "k8s.io/apimachinery/pkg/api/testing"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/serializer"
 )
 
 var _ runtime.Object = &Example{}
@@ -26,3 +33,31 @@ var _ metav1.ObjectMetaAccessor = &Example{}
 
 var _ runtime.Object = &ExampleList{}
 var _ metav1.ListMetaAccessor = &ExampleList{}
+
+func exampleFuzzerFuncs(t apitesting.TestingCommon) []interface{} {
+	return []interface{}{
+		func(obj *ExampleList, c fuzz.Continue) {
+			c.FuzzNoCustom(obj)
+			obj.Items = make([]Example, c.Intn(10))
+			for i := range obj.Items {
+				c.Fuzz(&obj.Items[i])
+			}
+		},
+	}
+}
+
+// TestRoundTrip tests that the third-party kinds can be marshaled and unmarshaled correctly to/from JSON
+// without the loss of information. Moreover, deep copy is tested.
+func TestRoundTrip(t *testing.T) {
+	scheme := runtime.NewScheme()
+	codecs := serializer.NewCodecFactory(scheme)
+
+	AddToScheme(scheme)
+
+	seed := rand.Int63()
+	fuzzerFuncs := apitesting.MergeFuzzerFuncs(t, apitesting.GenericFuzzerFuncs(t, codecs), exampleFuzzerFuncs(t))
+	fuzzer := apitesting.FuzzerFor(fuzzerFuncs, rand.NewSource(seed))
+
+	apitesting.RoundTripSpecificKindWithoutProtobuf(t, SchemeGroupVersion.WithKind("Example"), scheme, codecs, fuzzer, nil)
+	apitesting.RoundTripSpecificKindWithoutProtobuf(t, SchemeGroupVersion.WithKind("ExampleList"), scheme, codecs, fuzzer, nil)
+}