add item + union and item + zeroroneof output tests

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/union/simple/doc.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// +k8s:validation-gen=TypeMeta
+// +k8s:validation-gen-scheme-registry=k8s.io/code-generator/cmd/validation-gen/testscheme.Scheme
+
+// This is a test package.
+package unionsimple
+
+import "k8s.io/code-generator/cmd/validation-gen/testscheme"
+
+var localSchemeBuilder = testscheme.New()
+
+type Struct struct {
+	TypeMeta int `json:"typeMeta"`
+
+	// +k8s:listType=map
+	// +k8s:listMapKey=name
+	// +k8s:item(name: "succeeded")=+k8s:unionMember
+	// +k8s:item(name: "failed")=+k8s:unionMember
+	Tasks []Task `json:"tasks"`
+}
+
+type Task struct {
+	Name  string `json:"name"`
+	State string `json:"state"`
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/union/simple/doc_test.go

@@ -0,0 +1,64 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package unionsimple
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+func Test(t *testing.T) {
+	st := localSchemeBuilder.Test(t)
+
+	st.Value(&Struct{
+		Tasks: []Task{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "other", State: "Other"},
+		},
+	}).ExpectValid()
+
+	invalidBothSet := &Struct{
+		Tasks: []Task{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "failed", State: "Failed"},
+		},
+	}
+
+	st.Value(invalidBothSet).ExpectMatches(
+		field.ErrorMatcher{},
+		field.ErrorList{
+			field.Invalid(field.NewPath("tasks"), "{Tasks[{\"name\": \"failed\"}], Tasks[{\"name\": \"succeeded\"}]}",
+				"must specify exactly one of: `Tasks[{\"name\": \"succeeded\"}]`, `Tasks[{\"name\": \"failed\"}]`"),
+		},
+	)
+
+	invalidEmpty := &Struct{
+		Tasks: []Task{},
+	}
+	st.Value(invalidEmpty).ExpectMatches(
+		field.ErrorMatcher{},
+		field.ErrorList{
+			field.Invalid(field.NewPath("tasks"), "",
+				"must specify one of: `Tasks[{\"name\": \"succeeded\"}]`, `Tasks[{\"name\": \"failed\"}]`"),
+		},
+	)
+
+	// Test ratcheting.
+	st.Value(invalidEmpty).OldValue(invalidEmpty).ExpectValid()
+	st.Value(invalidBothSet).OldValue(invalidBothSet).ExpectValid()
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/union/simple/zz_generated.validations.go

@@ -0,0 +1,82 @@
+//go:build !ignore_autogenerated
+// +build !ignore_autogenerated
+
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Code generated by validation-gen. DO NOT EDIT.
+
+package unionsimple
+
+import (
+	context "context"
+	fmt "fmt"
+
+	equality "k8s.io/apimachinery/pkg/api/equality"
+	operation "k8s.io/apimachinery/pkg/api/operation"
+	safe "k8s.io/apimachinery/pkg/api/safe"
+	validate "k8s.io/apimachinery/pkg/api/validate"
+	field "k8s.io/apimachinery/pkg/util/validation/field"
+	testscheme "k8s.io/code-generator/cmd/validation-gen/testscheme"
+)
+
+func init() { localSchemeBuilder.Register(RegisterValidations) }
+
+// RegisterValidations adds validation functions to the given scheme.
+// Public to allow building arbitrary schemes.
+func RegisterValidations(scheme *testscheme.Scheme) error {
+	scheme.AddValidationFunc((*Struct)(nil), func(ctx context.Context, op operation.Operation, obj, oldObj interface{}) field.ErrorList {
+		switch op.Request.SubresourcePath() {
+		case "/":
+			return Validate_Struct(ctx, op, nil /* fldPath */, obj.(*Struct), safe.Cast[*Struct](oldObj))
+		}
+		return field.ErrorList{field.InternalError(nil, fmt.Errorf("no validation found for %T, subresource: %v", obj, op.Request.SubresourcePath()))}
+	})
+	return nil
+}
+
+var unionMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_union_simple_Struct_Tasks_ = validate.NewUnionMembership([2]string{"Tasks[{\"name\": \"succeeded\"}]", ""}, [2]string{"Tasks[{\"name\": \"failed\"}]", ""})
+
+func Validate_Struct(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *Struct) (errs field.ErrorList) {
+	// field Struct.TypeMeta has no validation
+
+	// field Struct.Tasks
+	errs = append(errs,
+		func(fldPath *field.Path, obj, oldObj []Task) (errs field.ErrorList) {
+			if op.Type == operation.Update && equality.Semantic.DeepEqual(obj, oldObj) {
+				return nil // no changes
+			}
+			errs = append(errs, validate.Unique(ctx, op, fldPath, obj, oldObj, func(a Task, b Task) bool { return a.Name == b.Name })...)
+			errs = append(errs, validate.Union(ctx, op, fldPath, obj, oldObj, unionMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_union_simple_Struct_Tasks_, func(list []Task) bool {
+				for i := range list {
+					if list[i].Name == "failed" {
+						return true
+					}
+				}
+				return false
+			}, func(list []Task) bool {
+				for i := range list {
+					if list[i].Name == "succeeded" {
+						return true
+					}
+				}
+				return false
+			})...)
+			return
+		}(fldPath.Child("tasks"), obj.Tasks, safe.Field(oldObj, func(oldObj *Struct) []Task { return oldObj.Tasks }))...)
+
+	return errs
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/union/typedef/doc.go

@@ -0,0 +1,42 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// +k8s:validation-gen=TypeMeta
+// +k8s:validation-gen-scheme-registry=k8s.io/code-generator/cmd/validation-gen/testscheme.Scheme
+
+// This is a test package.
+package uniontypedef
+
+import "k8s.io/code-generator/cmd/validation-gen/testscheme"
+
+var localSchemeBuilder = testscheme.New()
+
+type Struct struct {
+	TypeMeta int `json:"typeMeta"`
+
+	Tasks TaskList `json:"tasks"`
+}
+
+// +k8s:listType=map
+// +k8s:listMapKey=name
+// +k8s:item(name: "succeeded")=+k8s:unionMember
+// +k8s:item(name: "failed")=+k8s:unionMember
+type TaskList []Task
+
+type Task struct {
+	Name  string `json:"name"`
+	State string `json:"state"`
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/union/typedef/doc_test.go

@@ -0,0 +1,65 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package uniontypedef
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+func Test(t *testing.T) {
+	st := localSchemeBuilder.Test(t)
+
+	st.Value(&Struct{
+		Tasks: TaskList{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "other", State: "Other"},
+		},
+	}).ExpectValid()
+
+	invalidBothSet := &Struct{
+		Tasks: []Task{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "failed", State: "Failed"},
+		},
+	}
+
+	st.Value(invalidBothSet).ExpectMatches(
+		field.ErrorMatcher{},
+		field.ErrorList{
+			field.Invalid(field.NewPath("tasks"), "{TaskList[{\"name\": \"failed\"}], TaskList[{\"name\": \"succeeded\"}]}",
+				"must specify exactly one of: `TaskList[{\"name\": \"succeeded\"}]`, `TaskList[{\"name\": \"failed\"}]`"),
+		},
+	)
+
+	invalidEmpty := &Struct{
+		Tasks: TaskList{},
+	}
+	st.Value(invalidEmpty).ExpectMatches(
+		field.ErrorMatcher{},
+		field.ErrorList{
+			field.Invalid(field.NewPath("tasks"), "",
+				"must specify one of: `TaskList[{\"name\": \"succeeded\"}]`, `TaskList[{\"name\": \"failed\"}]`"),
+		},
+	)
+
+	// Test ratcheting.
+	st.Value(invalidEmpty).OldValue(invalidEmpty).ExpectValid()
+
+	st.Value(invalidBothSet).OldValue(invalidBothSet).ExpectValid()
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/union/typedef/zz_generated.validations.go

@@ -0,0 +1,93 @@
+//go:build !ignore_autogenerated
+// +build !ignore_autogenerated
+
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Code generated by validation-gen. DO NOT EDIT.
+
+package uniontypedef
+
+import (
+	context "context"
+	fmt "fmt"
+
+	equality "k8s.io/apimachinery/pkg/api/equality"
+	operation "k8s.io/apimachinery/pkg/api/operation"
+	safe "k8s.io/apimachinery/pkg/api/safe"
+	validate "k8s.io/apimachinery/pkg/api/validate"
+	field "k8s.io/apimachinery/pkg/util/validation/field"
+	testscheme "k8s.io/code-generator/cmd/validation-gen/testscheme"
+)
+
+func init() { localSchemeBuilder.Register(RegisterValidations) }
+
+// RegisterValidations adds validation functions to the given scheme.
+// Public to allow building arbitrary schemes.
+func RegisterValidations(scheme *testscheme.Scheme) error {
+	scheme.AddValidationFunc((*Struct)(nil), func(ctx context.Context, op operation.Operation, obj, oldObj interface{}) field.ErrorList {
+		switch op.Request.SubresourcePath() {
+		case "/":
+			return Validate_Struct(ctx, op, nil /* fldPath */, obj.(*Struct), safe.Cast[*Struct](oldObj))
+		}
+		return field.ErrorList{field.InternalError(nil, fmt.Errorf("no validation found for %T, subresource: %v", obj, op.Request.SubresourcePath()))}
+	})
+	return nil
+}
+
+func Validate_Struct(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *Struct) (errs field.ErrorList) {
+	// field Struct.TypeMeta has no validation
+
+	// field Struct.Tasks
+	errs = append(errs,
+		func(fldPath *field.Path, obj, oldObj TaskList) (errs field.ErrorList) {
+			if op.Type == operation.Update && equality.Semantic.DeepEqual(obj, oldObj) {
+				return nil // no changes
+			}
+			errs = append(errs, validate.Unique(ctx, op, fldPath, obj, oldObj, func(a Task, b Task) bool { return a.Name == b.Name })...)
+			errs = append(errs, Validate_TaskList(ctx, op, fldPath, obj, oldObj)...)
+			return
+		}(fldPath.Child("tasks"), obj.Tasks, safe.Field(oldObj, func(oldObj *Struct) TaskList { return oldObj.Tasks }))...)
+
+	return errs
+}
+
+var unionMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_union_typedef_TaskList_ = validate.NewUnionMembership([2]string{"TaskList[{\"name\": \"succeeded\"}]", ""}, [2]string{"TaskList[{\"name\": \"failed\"}]", ""})
+
+func Validate_TaskList(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj TaskList) (errs field.ErrorList) {
+	// type TaskList
+	if op.Type == operation.Update && equality.Semantic.DeepEqual(obj, oldObj) {
+		return nil // no changes
+	}
+	errs = append(errs, validate.Unique(ctx, op, fldPath, obj, oldObj, func(a Task, b Task) bool { return a.Name == b.Name })...)
+	errs = append(errs, validate.Union(ctx, op, fldPath, obj, oldObj, unionMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_union_typedef_TaskList_, func(list TaskList) bool {
+		for i := range list {
+			if list[i].Name == "failed" {
+				return true
+			}
+		}
+		return false
+	}, func(list TaskList) bool {
+		for i := range list {
+			if list[i].Name == "succeeded" {
+				return true
+			}
+		}
+		return false
+	})...)
+
+	return errs
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/zerorooneof/simple/doc.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// +k8s:validation-gen=TypeMeta
+// +k8s:validation-gen-scheme-registry=k8s.io/code-generator/cmd/validation-gen/testscheme.Scheme
+
+// This is a test package.
+package zeroroneofsimple
+
+import "k8s.io/code-generator/cmd/validation-gen/testscheme"
+
+var localSchemeBuilder = testscheme.New()
+
+type Struct struct {
+	TypeMeta int `json:"typeMeta"`
+
+	// +k8s:listType=map
+	// +k8s:listMapKey=name
+	// +k8s:item(name: "succeeded")=+k8s:zeroOrOneOfMember
+	// +k8s:item(name: "failed")=+k8s:zeroOrOneOfMember
+	Tasks []Task `json:"tasks"`
+}
+
+type Task struct {
+	Name  string `json:"name"`
+	State string `json:"state"`
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/zerorooneof/simple/doc_test.go

@@ -0,0 +1,59 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package zeroroneofsimple
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+func Test(t *testing.T) {
+	st := localSchemeBuilder.Test(t)
+
+	st.Value(&Struct{
+		Tasks: []Task{
+			{Name: "other", State: "Other"},
+		},
+	}).ExpectValid()
+
+	st.Value(&Struct{
+		Tasks: []Task{
+			{Name: "succeeded", State: "Succeeded"},
+		},
+	}).ExpectValid()
+
+	st.Value(&Struct{
+		Tasks: []Task{},
+	}).ExpectValid()
+
+	invalidBothSet := &Struct{
+		Tasks: []Task{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "failed", State: "Failed"},
+		},
+	}
+	st.Value(invalidBothSet).ExpectMatches(
+		field.ErrorMatcher{}.ByType().ByField().ByOrigin(),
+		field.ErrorList{
+			field.Invalid(field.NewPath("tasks"), nil, "").WithOrigin("zeroOrOneOf"),
+		},
+	)
+
+	// Test ratcheting.
+	st.Value(invalidBothSet).OldValue(invalidBothSet).ExpectValid()
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/zerorooneof/simple/zz_generated.validations.go

@@ -0,0 +1,82 @@
+//go:build !ignore_autogenerated
+// +build !ignore_autogenerated
+
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Code generated by validation-gen. DO NOT EDIT.
+
+package zeroroneofsimple
+
+import (
+	context "context"
+	fmt "fmt"
+
+	equality "k8s.io/apimachinery/pkg/api/equality"
+	operation "k8s.io/apimachinery/pkg/api/operation"
+	safe "k8s.io/apimachinery/pkg/api/safe"
+	validate "k8s.io/apimachinery/pkg/api/validate"
+	field "k8s.io/apimachinery/pkg/util/validation/field"
+	testscheme "k8s.io/code-generator/cmd/validation-gen/testscheme"
+)
+
+func init() { localSchemeBuilder.Register(RegisterValidations) }
+
+// RegisterValidations adds validation functions to the given scheme.
+// Public to allow building arbitrary schemes.
+func RegisterValidations(scheme *testscheme.Scheme) error {
+	scheme.AddValidationFunc((*Struct)(nil), func(ctx context.Context, op operation.Operation, obj, oldObj interface{}) field.ErrorList {
+		switch op.Request.SubresourcePath() {
+		case "/":
+			return Validate_Struct(ctx, op, nil /* fldPath */, obj.(*Struct), safe.Cast[*Struct](oldObj))
+		}
+		return field.ErrorList{field.InternalError(nil, fmt.Errorf("no validation found for %T, subresource: %v", obj, op.Request.SubresourcePath()))}
+	})
+	return nil
+}
+
+var zeroOrOneOfMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_zerorooneof_simple_Struct_Tasks_ = validate.NewUnionMembership([2]string{"Tasks[{\"name\": \"succeeded\"}]", ""}, [2]string{"Tasks[{\"name\": \"failed\"}]", ""})
+
+func Validate_Struct(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *Struct) (errs field.ErrorList) {
+	// field Struct.TypeMeta has no validation
+
+	// field Struct.Tasks
+	errs = append(errs,
+		func(fldPath *field.Path, obj, oldObj []Task) (errs field.ErrorList) {
+			if op.Type == operation.Update && equality.Semantic.DeepEqual(obj, oldObj) {
+				return nil // no changes
+			}
+			errs = append(errs, validate.Unique(ctx, op, fldPath, obj, oldObj, func(a Task, b Task) bool { return a.Name == b.Name })...)
+			errs = append(errs, validate.ZeroOrOneOfUnion(ctx, op, fldPath, obj, oldObj, zeroOrOneOfMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_zerorooneof_simple_Struct_Tasks_, func(list []Task) bool {
+				for i := range list {
+					if list[i].Name == "failed" {
+						return true
+					}
+				}
+				return false
+			}, func(list []Task) bool {
+				for i := range list {
+					if list[i].Name == "succeeded" {
+						return true
+					}
+				}
+				return false
+			})...)
+			return
+		}(fldPath.Child("tasks"), obj.Tasks, safe.Field(oldObj, func(oldObj *Struct) []Task { return oldObj.Tasks }))...)
+
+	return errs
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/zerorooneof/typedef/doc.go

@@ -0,0 +1,42 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// +k8s:validation-gen=TypeMeta
+// +k8s:validation-gen-scheme-registry=k8s.io/code-generator/cmd/validation-gen/testscheme.Scheme
+
+// This is a test package.
+package zeroroneooftypedef
+
+import "k8s.io/code-generator/cmd/validation-gen/testscheme"
+
+var localSchemeBuilder = testscheme.New()
+
+type Struct struct {
+	TypeMeta int `json:"typeMeta"`
+
+	Tasks TaskList `json:"tasks"`
+}
+
+// +k8s:listType=map
+// +k8s:listMapKey=name
+// +k8s:item(name: "succeeded")=+k8s:zeroOrOneOfMember
+// +k8s:item(name: "failed")=+k8s:zeroOrOneOfMember
+type TaskList []Task
+
+type Task struct {
+	Name  string `json:"name"`
+	State string `json:"state"`
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/zerorooneof/typedef/doc_test.go

@@ -0,0 +1,61 @@
+/*
+Copyright 2025 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package zeroroneooftypedef
+
+import (
+	"testing"
+
+	"k8s.io/apimachinery/pkg/util/validation/field"
+)
+
+func Test(t *testing.T) {
+	st := localSchemeBuilder.Test(t)
+
+	st.Value(&Struct{
+		Tasks: TaskList{
+			{Name: "other", State: "Other"},
+		},
+	}).ExpectValid()
+
+	st.Value(&Struct{
+		Tasks: TaskList{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "other", State: "Other"},
+		},
+	}).ExpectValid()
+
+	st.Value(&Struct{
+		Tasks: TaskList{},
+	}).ExpectValid()
+
+	invalidBothSet := &Struct{
+		Tasks: TaskList{
+			{Name: "succeeded", State: "Succeeded"},
+			{Name: "failed", State: "Failed"},
+		},
+	}
+
+	st.Value(invalidBothSet).ExpectMatches(
+		field.ErrorMatcher{}.ByType().ByField().ByOrigin(),
+		field.ErrorList{
+			field.Invalid(field.NewPath("tasks"), nil, "").WithOrigin("zeroOrOneOf"),
+		},
+	)
+
+	// Test ratcheting.
+	st.Value(invalidBothSet).OldValue(invalidBothSet).ExpectValid()
+}

staging/src/k8s.io/code-generator/cmd/validation-gen/output_tests/tags/item/zerorooneof/typedef/zz_generated.validations.go

@@ -0,0 +1,93 @@
+//go:build !ignore_autogenerated
+// +build !ignore_autogenerated
+
+/*
+Copyright The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Code generated by validation-gen. DO NOT EDIT.
+
+package zeroroneooftypedef
+
+import (
+	context "context"
+	fmt "fmt"
+
+	equality "k8s.io/apimachinery/pkg/api/equality"
+	operation "k8s.io/apimachinery/pkg/api/operation"
+	safe "k8s.io/apimachinery/pkg/api/safe"
+	validate "k8s.io/apimachinery/pkg/api/validate"
+	field "k8s.io/apimachinery/pkg/util/validation/field"
+	testscheme "k8s.io/code-generator/cmd/validation-gen/testscheme"
+)
+
+func init() { localSchemeBuilder.Register(RegisterValidations) }
+
+// RegisterValidations adds validation functions to the given scheme.
+// Public to allow building arbitrary schemes.
+func RegisterValidations(scheme *testscheme.Scheme) error {
+	scheme.AddValidationFunc((*Struct)(nil), func(ctx context.Context, op operation.Operation, obj, oldObj interface{}) field.ErrorList {
+		switch op.Request.SubresourcePath() {
+		case "/":
+			return Validate_Struct(ctx, op, nil /* fldPath */, obj.(*Struct), safe.Cast[*Struct](oldObj))
+		}
+		return field.ErrorList{field.InternalError(nil, fmt.Errorf("no validation found for %T, subresource: %v", obj, op.Request.SubresourcePath()))}
+	})
+	return nil
+}
+
+func Validate_Struct(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj *Struct) (errs field.ErrorList) {
+	// field Struct.TypeMeta has no validation
+
+	// field Struct.Tasks
+	errs = append(errs,
+		func(fldPath *field.Path, obj, oldObj TaskList) (errs field.ErrorList) {
+			if op.Type == operation.Update && equality.Semantic.DeepEqual(obj, oldObj) {
+				return nil // no changes
+			}
+			errs = append(errs, validate.Unique(ctx, op, fldPath, obj, oldObj, func(a Task, b Task) bool { return a.Name == b.Name })...)
+			errs = append(errs, Validate_TaskList(ctx, op, fldPath, obj, oldObj)...)
+			return
+		}(fldPath.Child("tasks"), obj.Tasks, safe.Field(oldObj, func(oldObj *Struct) TaskList { return oldObj.Tasks }))...)
+
+	return errs
+}
+
+var zeroOrOneOfMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_zerorooneof_typedef_TaskList_ = validate.NewUnionMembership([2]string{"TaskList[{\"name\": \"succeeded\"}]", ""}, [2]string{"TaskList[{\"name\": \"failed\"}]", ""})
+
+func Validate_TaskList(ctx context.Context, op operation.Operation, fldPath *field.Path, obj, oldObj TaskList) (errs field.ErrorList) {
+	// type TaskList
+	if op.Type == operation.Update && equality.Semantic.DeepEqual(obj, oldObj) {
+		return nil // no changes
+	}
+	errs = append(errs, validate.Unique(ctx, op, fldPath, obj, oldObj, func(a Task, b Task) bool { return a.Name == b.Name })...)
+	errs = append(errs, validate.ZeroOrOneOfUnion(ctx, op, fldPath, obj, oldObj, zeroOrOneOfMembershipFor_k8s_io_code_generator_cmd_validation_gen_output_tests_tags_item_zerorooneof_typedef_TaskList_, func(list TaskList) bool {
+		for i := range list {
+			if list[i].Name == "failed" {
+				return true
+			}
+		}
+		return false
+	}, func(list TaskList) bool {
+		for i := range list {
+			if list[i].Name == "succeeded" {
+				return true
+			}
+		}
+		return false
+	})...)
+
+	return errs
+}