Merge pull request #132499 from liggitt/unwanted-json-patch-v5

Add json-patch v4 compatibility test

hack/unwanted-dependencies.json

@@ -20,6 +20,7 @@
       "github.com/bketelsen/crypt": "unused, crypto",
       "github.com/containerd/cgroups": "standardize on single cgroups library from runc, refer #128157",
       "github.com/davecgh/go-spew": "refer to #103942",
+      "github.com/evanphx/json-patch/v5": "refer to https://github.com/kubernetes/kubernetes/pull/91622#issuecomment-637087847",
       "github.com/form3tech-oss/jwt-go": "unmaintained, archive mode",
       "github.com/getsentry/raven-go": "unmaintained, archive mode",
       "github.com/go-bindata/go-bindata": "refer to #99829",

staging/src/k8s.io/apiserver/pkg/endpoints/handlers/rest_test.go

@@ -29,6 +29,7 @@ import (
 
 	"github.com/google/go-cmp/cmp"
 	jsonpatch "gopkg.in/evanphx/json-patch.v4"
+
 	apiequality "k8s.io/apimachinery/pkg/api/equality"
 	apierrors "k8s.io/apimachinery/pkg/api/errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -249,6 +250,15 @@ func TestJSONPatch(t *testing.T) {
 			name:  "valid-negative-index-patch",
 			patch: `[{"op": "test", "value": "foo", "path": "/metadata/finalizers/-1"}]`,
 		},
+		// This demonstrates out-of-spec behavior json-patch v4 allows,
+		// which Kubernetes clients may depend on, and which updating to json-patch v5 currently breaks
+		{
+			name: "replace-missing-path-allowed",
+			patch: `[
+				{"op":"replace", "path":"/metadata/path", "value":"foo"},
+				{"op":"test", "path":"/metadata/path", "value":"foo"}
+			]`,
+		},
 	} {
 		p := &patcher{
 			patchType:  types.JSONPatchType,