managedfields: Create NewFakeFieldManager

And simplify how a lot of the fakes are created. Notably, the converter
was never really used to do anything so this is simplified.

staging/src/k8s.io/apimachinery/pkg/util/managedfields/internal/skipnonapplied_test.go

@@ -33,7 +33,7 @@ func TestNoUpdateBeforeFirstApply(t *testing.T) {
 	f := internaltesting.NewTestFieldManagerImpl(fakeTypeConverter, schema.FromAPIVersionAndKind("v1", "Pod"), "", func(m internal.Manager) internal.Manager {
 		return internal.NewSkipNonAppliedManager(
 			m,
-			internaltesting.NewFakeObjectCreater(),
+			&internaltesting.FakeObjectCreater{},
 			schema.FromAPIVersionAndKind("v1", "Pod"),
 		)
 	})
@@ -73,7 +73,7 @@ func TestUpdateBeforeFirstApply(t *testing.T) {
 	f := internaltesting.NewTestFieldManagerImpl(fakeTypeConverter, schema.FromAPIVersionAndKind("v1", "Pod"), "", func(m internal.Manager) internal.Manager {
 		return internal.NewSkipNonAppliedManager(
 			m,
-			internaltesting.NewFakeObjectCreater(),
+			&internaltesting.FakeObjectCreater{},
 			schema.FromAPIVersionAndKind("v1", "Pod"),
 		)
 	})

staging/src/k8s.io/apimachinery/pkg/util/managedfields/internal/testing/testfieldmanager.go

@@ -27,62 +27,42 @@ import (
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/util/managedfields"
 	"k8s.io/apimachinery/pkg/util/managedfields/internal"
-	"sigs.k8s.io/structured-merge-diff/v4/fieldpath"
-	"sigs.k8s.io/structured-merge-diff/v4/merge"
-	"sigs.k8s.io/structured-merge-diff/v4/typed"
 )
 
-// NewFakeObjectCreater implements ObjectCreater, it can create empty
+// FakeObjectCreater implements ObjectCreater, it can create empty
 // objects (unstructured) of the given GVK.
-func NewFakeObjectCreater() runtime.ObjectCreater {
+type FakeObjectCreater struct{}
-	return &fakeObjectCreater{}
-}
 
-type fakeObjectCreater struct{}
+func (f *FakeObjectCreater) New(gvk schema.GroupVersionKind) (runtime.Object, error) {
-
-func (f *fakeObjectCreater) New(gvk schema.GroupVersionKind) (runtime.Object, error) {
 	u := unstructured.Unstructured{Object: map[string]interface{}{}}
 	u.SetAPIVersion(gvk.GroupVersion().String())
 	u.SetKind(gvk.Kind)
 	return &u, nil
 }
 
-type fakeObjectConvertor struct {
+// FakeObjectConvertor implements runtime.ObjectConvertor but it
-	converter  merge.Converter
+// actually does nothing but return its input.
-	apiVersion fieldpath.APIVersion
+type FakeObjectConvertor struct{}
-}
 
 //nolint:staticcheck,ineffassign // SA4009 backwards compatibility
-func (c *fakeObjectConvertor) Convert(in, out, context interface{}) error {
+func (c *FakeObjectConvertor) Convert(in, out, context interface{}) error {
-	if typedValue, ok := in.(*typed.TypedValue); ok {
+	out = in
-		var err error
-		out, err = c.converter.Convert(typedValue, c.apiVersion)
-		return err
-	}
 	return nil
 }
 
-func (c *fakeObjectConvertor) ConvertToVersion(in runtime.Object, _ runtime.GroupVersioner) (runtime.Object, error) {
+func (c *FakeObjectConvertor) ConvertToVersion(in runtime.Object, _ runtime.GroupVersioner) (runtime.Object, error) {
 	return in, nil
 }
 
-func (c *fakeObjectConvertor) ConvertFieldLabel(_ schema.GroupVersionKind, _, _ string) (string, string, error) {
+func (c *FakeObjectConvertor) ConvertFieldLabel(_ schema.GroupVersionKind, _, _ string) (string, string, error) {
 	return "", "", errors.New("not implemented")
 }
 
-type fakeObjectDefaulter struct{}
+// FakeObjectDefaulter implements runtime.Defaulter, but it actually
+// does nothing.
+type FakeObjectDefaulter struct{}
 
-func (d *fakeObjectDefaulter) Default(in runtime.Object) {}
+func (d *FakeObjectDefaulter) Default(in runtime.Object) {}
-
-type sameVersionConverter struct{}
-
-func (sameVersionConverter) Convert(object *typed.TypedValue, version fieldpath.APIVersion) (*typed.TypedValue, error) {
-	return object, nil
-}
-
-func (sameVersionConverter) IsMissingVersionError(error) bool {
-	return false
-}
 
 type TestFieldManagerImpl struct {
 	fieldManager *internal.FieldManager
@@ -139,12 +119,10 @@ func (f *TestFieldManagerImpl) ManagedFields() []metav1.ManagedFieldsEntry {
 
 // NewTestFieldManager creates a new manager for the given GVK.
 func NewTestFieldManagerImpl(typeConverter managedfields.TypeConverter, gvk schema.GroupVersionKind, subresource string, chainFieldManager func(internal.Manager) internal.Manager) *TestFieldManagerImpl {
-	apiVersion := fieldpath.APIVersion(gvk.GroupVersion().String())
-	objectConverter := &fakeObjectConvertor{sameVersionConverter{}, apiVersion}
 	f, err := internal.NewStructuredMergeManager(
 		typeConverter,
-		objectConverter,
+		&FakeObjectConvertor{},
-		&fakeObjectDefaulter{},
+		&FakeObjectDefaulter{},
 		gvk.GroupVersion(),
 		gvk.GroupVersion(),
 		nil,
@@ -166,8 +144,8 @@ func NewTestFieldManagerImpl(typeConverter managedfields.TypeConverter, gvk sche
 					internal.NewManagedFieldsUpdater(
 						internal.NewStripMetaManager(f),
 					), gvk.GroupVersion(), subresource,
-				), NewFakeObjectCreater(), gvk, internal.DefaultTrackOnCreateProbability,
+				), &FakeObjectCreater{}, gvk, internal.DefaultTrackOnCreateProbability,
-			), typeConverter, objectConverter, gvk.GroupVersion(),
+			), typeConverter, &FakeObjectConvertor{}, gvk.GroupVersion(),
 		),
 	)
 	if chainFieldManager != nil {

staging/src/k8s.io/apimachinery/pkg/util/managedfields/managedfieldstest/testfieldmanager.go

@@ -63,4 +63,32 @@ func NewTestFieldManager(typeConverter managedfields.TypeConverter, gvk schema.G
 // for the given gvk, on the given sub-resource.
 func NewTestFieldManagerSubresource(typeConverter managedfields.TypeConverter, gvk schema.GroupVersionKind, subresource string) TestFieldManager {
 	return testing.NewTestFieldManagerImpl(typeConverter, gvk, subresource, nil)
+
+}
+
+// NewFakeFieldManager creates an actual FieldManager but that doesn't
+// perform any conversion. This is just a convenience for tests to
+// create an actual manager that they can use but in very restricted
+// ways.
+//
+// This is different from the TestFieldManager because it's not meant to
+// assert values, or hold the state, this acts like a normal
+// FieldManager.
+//
+// Also, this only operates on the main-resource, and sub-resource can't
+// be configured.
+func NewFakeFieldManager(typeConverter managedfields.TypeConverter, gvk schema.GroupVersionKind) *managedfields.FieldManager {
+	ffm, err := managedfields.NewDefaultFieldManager(
+		typeConverter,
+		&testing.FakeObjectConvertor{},
+		&testing.FakeObjectDefaulter{},
+		&testing.FakeObjectCreater{},
+		gvk,
+		gvk.GroupVersion(),
+		"",
+		nil)
+	if err != nil {
+		panic(err)
+	}
+	return ffm
 }