add fetching into discovery client for OpenAPI v3

reflect latest struct changes

use correct discovery openapi test data layout

make the OpenAPIv3 interface less blue

field grouping

add copyrights

implement cached discovery client

add cached discovery tests

address review feedback

Kubernetes-commit: 075866b3e3ea029c243d82d8d6eb99e96d9c49d3

discovery/discovery_client_test.go

@@ -28,6 +28,7 @@ import (
 
 	"github.com/gogo/protobuf/proto"
 	openapi_v2 "github.com/google/gnostic/openapiv2"
+	openapi_v3 "github.com/google/gnostic/openapiv3"
 	"github.com/stretchr/testify/assert"
 	golangproto "google.golang.org/protobuf/proto"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -36,6 +37,7 @@ import (
 	"k8s.io/apimachinery/pkg/util/sets"
 	"k8s.io/apimachinery/pkg/version"
 	restclient "k8s.io/client-go/rest"
+	testutil "k8s.io/client-go/util/testing"
 )
 
 func TestGetServerVersion(t *testing.T) {
@@ -535,6 +537,14 @@ func openapiSchemaFakeServer(t *testing.T) (*httptest.Server, error) {
 	return server, nil
 }
 
+func openapiV3SchemaFakeServer(t *testing.T) (*httptest.Server, map[string]*openapi_v3.Document, error) {
+	res, err := testutil.NewFakeOpenAPIV3Server("testdata")
+	if err != nil {
+		return nil, nil, err
+	}
+	return res.HttpServer, res.ServedDocuments, nil
+}
+
 func TestGetOpenAPISchema(t *testing.T) {
 	server, err := openapiSchemaFakeServer(t)
 	if err != nil {
@@ -552,6 +562,45 @@ func TestGetOpenAPISchema(t *testing.T) {
 	}
 }
 
+func TestGetOpenAPISchemaV3(t *testing.T) {
+	server, testV3Specs, err := openapiV3SchemaFakeServer(t)
+	if err != nil {
+		t.Errorf("unexpected error starting fake server: %v", err)
+	}
+	defer server.Close()
+
+	client := NewDiscoveryClientForConfigOrDie(&restclient.Config{Host: server.URL})
+	openapiClient := client.OpenAPIV3()
+	paths, err := openapiClient.Paths()
+	if err != nil {
+		t.Fatalf("unexpected error getting openapi: %v", err)
+	}
+
+	for k, v := range paths {
+		actual, err := v.Schema()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		expected := testV3Specs[k]
+		if !golangproto.Equal(expected, actual) {
+			t.Fatalf("expected \n%v\n\ngot:\n%v", expected, actual)
+		}
+
+		// Ensure that fetching schema once again does not return same instance
+		actualAgain, err := v.Schema()
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if reflect.ValueOf(actual).Pointer() == reflect.ValueOf(actualAgain).Pointer() {
+			t.Fatal("expected schema not to be cached")
+		} else if !golangproto.Equal(actual, actualAgain) {
+			t.Fatal("expected schema values to be equal")
+		}
+	}
+}
+
 func TestGetOpenAPISchemaForbiddenFallback(t *testing.T) {
 	server, err := openapiSchemaDeprecatedFakeServer(http.StatusForbidden, t)
 	if err != nil {