Try RESTClient

RESTClient gives us the ability to access API endpoint directly.
For the custom resources, we can access their API endpoint to get/update resources.

Author: JianLi-RH

.openshift-tests-extension/openshift_payload_cluster-version-operator.json

@@ -8,5 +8,15 @@
     "source": "openshift:payload:cluster-version-operator",
     "lifecycle": "blocking",
     "environmentSelector": {}
+  },
+  {
+    "name": "[Jira:\"Cluster Version Operator\"] cluster-version-operator-tests should support passing tests Demo",
+    "labels": {},
+    "resources": {
+      "isolation": {}
+    },
+    "source": "openshift:payload:cluster-version-operator",
+    "lifecycle": "blocking",
+    "environmentSelector": {}
   }
 ]

test/cvo/cvo.go

@@ -1,12 +1,45 @@
 package cvo
 
 import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+
 	g "github.com/onsi/ginkgo/v2"
 	o "github.com/onsi/gomega"
+	configv1 "github.com/openshift/api/config/v1"
+
+	"github.com/openshift/cluster-version-operator/test/utilities"
 )
 
 var _ = g.Describe(`[Jira:"Cluster Version Operator"] cluster-version-operator-tests should support passing tests`, func() {
 	g.It("the sanity test should pass", func() {
 		o.Expect(true).To(o.BeTrue())
 	})
+
+	g.It("Demo", func() {
+
+		result := &configv1.ClusterVersion{}
+		apiPath := "/apis/config.openshift.io/v1/clusterversions/version"
+
+		client := utilities.MustGetRestClient(configv1.GroupVersion.Group, configv1.GroupVersion.Version, apiPath)
+		err := client.
+			Get().
+			AbsPath(apiPath).
+			Namespace("default").
+			// Resource("clusterversion").
+			// Name("version").
+			Do(context.TODO()).Into(result)
+
+		o.Expect(err).NotTo(o.HaveOccurred(), err.Error())
+
+		jsonData, err := json.MarshalIndent(result, "", "  ")
+		if err != nil {
+			log.Fatalf("Error marshaling to JSON: %v", err)
+		}
+
+		// Print the JSON data as a string
+		fmt.Printf("Successfully retrieved data: %v", string(jsonData))
+	})
 })

test/utilities/connection.go

@@ -5,17 +5,26 @@ import (
 	"fmt"
 	"os"
 
+	"github.com/openshift/client-go/build/clientset/versioned/scheme"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/clientcmd"
 )
 
-// getKubeClient creates a Kubernetes clientset.
-func getKubeClient() (*kubernetes.Clientset, error) {
+func getClientConfig() (*rest.Config, error) {
 	configPath, present := os.LookupEnv("KUBECONFIG")
 	if !present {
 		return nil, errors.New("the environment variable KUBECONFIG must be set")
 	}
 	config, err := clientcmd.BuildConfigFromFlags("", configPath)
+	return config, err
+}
+
+// getKubeClient creates a Kubernetes clientset.
+func getKubeClient() (*kubernetes.Clientset, error) {
+	config, err := getClientConfig()
 	if err != nil {
 		return nil, fmt.Errorf("unable to load build config: %w", err)
 	}
@@ -24,14 +33,44 @@ func getKubeClient() (*kubernetes.Clientset, error) {
 	if err != nil {
 		return nil, fmt.Errorf("unable to create a Kubernetes clientset: %w", err)
 	}
+
 	return clientset, nil
 }
 
-// MustGetKubeClient creates a Kubernetes clientset, or panics on failures.
+// getRestClient creates a Kubernetes RESTClient instance, or panics on failures.
+// RESTClient is more powerfull than clientset which provides access to
+// the Kubernetes API as a set of basic REST primitives (GET, POST, PUT, DELETE).
+func getRestClient(groupName string, groupVersion string, apiPath string) (*rest.RESTClient, error) {
+	config, err := getClientConfig()
+	if err != nil {
+		return nil, fmt.Errorf("unable to load build config: %w", err)
+	}
+
+	config.APIPath = apiPath
+	config.GroupVersion = &schema.GroupVersion{Group: groupName, Version: groupVersion}
+	config.ContentType = runtime.ContentTypeJSON
+	config.NegotiatedSerializer = scheme.Codecs.WithoutConversion()
+
+	restClient, err := rest.RESTClientFor(config)
+	return restClient, err
+}
+
+// MustGetKubeClient creates a Kubernetes clientset instance, or panics on failures.
 func MustGetKubeClient() *kubernetes.Clientset {
 	clientset, err := getKubeClient()
 	if err != nil {
 		panic("unable to create a Kubernetes clientset: " + err.Error())
 	}
 	return clientset
 }
+
+// MustGetRestClient creates a Kubernetes RESTClient instance, or panics on failures.
+// RESTClient is more powerfull than clientset which provides access to
+// the Kubernetes API as a set of basic REST primitives (GET, POST, PUT, DELETE).
+func MustGetRestClient(groupName string, groupVersion string, apiPath string) *rest.RESTClient {
+	clientset, err := getRestClient(groupName, groupVersion, apiPath)
+	if err != nil {
+		panic("unable to create a RESTClient instance: " + err.Error())
+	}
+	return clientset
+}

test/utilities/deepcopy.go

@@ -0,0 +1,32 @@
+package utilities
+
+import "k8s.io/apimachinery/pkg/runtime"
+
+// DeepCopyInto copies all properties of this object into another object of the
+// same type that is provided as a pointer.
+func (in *Resourse) DeepCopyInto(out *Resourse) {
+	out.TypeMeta = in.TypeMeta
+	out.ObjectMeta = in.ObjectMeta
+	out.Spec = in.Spec
+	out.Status = in.Status
+}
+
+// DeepCopyObject returns a generically typed copy of an object
+func (in *Resourse) DeepCopyObject() runtime.Object {
+	out := Resourse{}
+	in.DeepCopyInto(&out)
+
+	return &out
+}
+
+func (in *ResourseList) DeepCopyObject() runtime.Object {
+	out := ResourseList{}
+	if in.Items != nil {
+		out.Items = make([]Resourse, len(in.Items))
+		for i := range in.Items {
+			in.Items[i].DeepCopyInto(&out.Items[i])
+		}
+	}
+
+	return &out
+}

test/utilities/object.go

@@ -0,0 +1,18 @@
+package utilities
+
+import metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+
+type Resourse struct {
+	metav1.TypeMeta `json:",inline"`
+
+	metav1.ObjectMeta `json:"metadata,omitempty"`
+
+	Spec map[string]any `json:"spec"`
+
+	Status map[string]any `json:"status"`
+}
+
+type ResourseList struct {
+	metav1.TypeMeta `json:",inline"`
+	Items           []Resourse `json:"items"`
+}