Add ConfigMap patch e2e test with validation step

Test originally written by draveness for this PR:
kubernetes#78924

This commit adds a validation step to the test.

Author: BobyMCbobs

test/e2e/common/configmap.go

@@ -27,6 +27,7 @@ import (
 	imageutils "k8s.io/kubernetes/test/utils/image"
 
 	"github.com/onsi/ginkgo"
+	"github.com/onsi/gomega"
 )
 
 var _ = ginkgo.Describe("[sig-node] ConfigMap", func() {
@@ -134,6 +135,27 @@ var _ = ginkgo.Describe("[sig-node] ConfigMap", func() {
 		configMap, err := newConfigMapWithEmptyKey(f)
 		framework.ExpectError(err, "created configMap %q with empty key in namespace %q", configMap.Name, f.Namespace.Name)
 	})
+
+	ginkgo.It("should patch ConfigMap successfully", func() {
+		name := "configmap-test-" + string(uuid.NewUUID())
+		configMap := newConfigMap(f, name)
+		configMapOriginalState := *configMap
+		ginkgo.By(fmt.Sprintf("Creating configMap %v/%v", f.Namespace.Name, configMap.Name))
+		_, err := f.ClientSet.CoreV1().ConfigMaps(f.Namespace.Name).Create(configMap)
+		framework.ExpectNoError(err)
+
+		configMap.Data = map[string]string{
+			"data": "value",
+		}
+		ginkgo.By(fmt.Sprintf("Updating configMap %v/%v", f.Namespace.Name, configMap.Name))
+		_, err = f.ClientSet.CoreV1().ConfigMaps(f.Namespace.Name).Update(configMap)
+		framework.ExpectNoError(err)
+
+		configMapFromUpdate, err := f.ClientSet.CoreV1().ConfigMaps(f.Namespace.Name).Get(name, metav1.GetOptions{})
+		framework.ExpectNoError(err)
+		ginkgo.By(fmt.Sprintf("Verifying update of configMap %v/%v", f.Namespace.Name, configMap.Name))
+		gomega.Expect(configMapFromUpdate.Data).NotTo(gomega.Equal(configMapOriginalState.Data))
+	})
 })
 
 func newEnvFromConfigMap(f *framework.Framework, name string) *v1.ConfigMap {