From 8ab8d05cc40c391f8ac650f50f23500666bfc943 Mon Sep 17 00:00:00 2001
From: David Eads <deads@redhat.com>
Date: Tue, 1 Mar 2022 11:51:16 -0500
Subject: [PATCH]  add resource enablement check for e2e tests of beta APIs

---
 .../src/k8s.io/client-go/discovery/helper.go  | 21 ++++++++++++++
 test/e2e/apimachinery/discovery.go            | 29 +++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/staging/src/k8s.io/client-go/discovery/helper.go b/staging/src/k8s.io/client-go/discovery/helper.go
index 3bfe514e823..e79f073b03a 100644
--- a/staging/src/k8s.io/client-go/discovery/helper.go
+++ b/staging/src/k8s.io/client-go/discovery/helper.go
@@ -19,12 +19,33 @@ package discovery
 import (
 	"fmt"
 
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/sets"
 	apimachineryversion "k8s.io/apimachinery/pkg/version"
 )
 
+// IsResourceEnabled queries the server to determine if the resource specified is present on the server.
+// This is particularly helpful when writing a controller or an e2e test that requires a particular resource to function.
+func IsResourceEnabled(client DiscoveryInterface, resourceToCheck schema.GroupVersionResource) (bool, error) {
+	// this is a single request.  The ServerResourcesForGroupVersion handles the core v1 group as legacy.
+	resourceList, err := client.ServerResourcesForGroupVersion(resourceToCheck.GroupVersion().String())
+	if apierrors.IsNotFound(err) { // if the discovery endpoint isn't present, then the resource isn't present.
+		return false, nil
+	}
+	if err != nil {
+		return false, err
+	}
+	for _, actualResource := range resourceList.APIResources {
+		if actualResource.Name == resourceToCheck.Resource {
+			return true, nil
+		}
+	}
+
+	return false, nil
+}
+
 // MatchesServerVersion queries the server to compares the build version
 // (git hash) of the client with the server's build version. It returns an error
 // if it failed to contact the server or if the versions are not an exact match.
diff --git a/test/e2e/apimachinery/discovery.go b/test/e2e/apimachinery/discovery.go
index 0fd96491571..04103aeeb5f 100644
--- a/test/e2e/apimachinery/discovery.go
+++ b/test/e2e/apimachinery/discovery.go
@@ -21,8 +21,10 @@ import (
 	"strings"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	utilversion "k8s.io/apimachinery/pkg/util/version"
 	"k8s.io/apiserver/pkg/endpoints/discovery"
+	clientdiscovery "k8s.io/client-go/discovery"
 	"k8s.io/kubernetes/test/e2e/framework"
 	e2eskipper "k8s.io/kubernetes/test/e2e/framework/skipper"
 	"k8s.io/kubernetes/test/utils/crd"
@@ -45,6 +47,33 @@ var _ = SIGDescribe("Discovery", func() {
 		setupServerCert(namespaceName, serviceName)
 	})
 
+	ginkgo.It("should accurately determine present and missing resources", func() {
+		// checks that legacy api group resources function
+		ok, err := clientdiscovery.IsResourceEnabled(f.ClientSet.Discovery(), schema.GroupVersionResource{Group: "", Version: "v1", Resource: "namespaces"})
+		framework.ExpectNoError(err)
+		if !ok {
+			framework.Failf("namespace.v1 should always be present")
+		}
+		// checks that non-legacy api group resources function
+		ok, err = clientdiscovery.IsResourceEnabled(f.ClientSet.Discovery(), schema.GroupVersionResource{Group: "apps", Version: "v1", Resource: "deployments"})
+		framework.ExpectNoError(err)
+		if !ok {
+			framework.Failf("deployments.v1.apps should always be present")
+		}
+		// checks that nonsense resources in existing api groups function
+		ok, err = clientdiscovery.IsResourceEnabled(f.ClientSet.Discovery(), schema.GroupVersionResource{Group: "apps", Version: "v1", Resource: "please-dont-ever-create-this"})
+		framework.ExpectNoError(err)
+		if ok {
+			framework.Failf("please-dont-ever-create-this.v1.apps should never be present")
+		}
+		// checks that resources resources in nonsense api groups function
+		ok, err = clientdiscovery.IsResourceEnabled(f.ClientSet.Discovery(), schema.GroupVersionResource{Group: "not-these-apps", Version: "v1", Resource: "deployments"})
+		framework.ExpectNoError(err)
+		if ok {
+			framework.Failf("deployments.v1.not-these-apps should never be present")
+		}
+	})
+
 	ginkgo.It("Custom resource should have storage version hash", func() {
 		testcrd, err := crd.CreateTestCRD(f)
 		if err != nil {