add JSONRoundTripTestCase and add a Test*RoundTrip for every spec.* type which needs it

adds subtest `UnmarshalEmbedded` that positively shows that there is at least one property per embedded field

also does not use field labels, so compiler errors are thrown in event any are missing

whoops

Author: alexzielenski

pkg/util/jsontesting/json_roundtrip.go

@@ -0,0 +1,113 @@
+/*
+Copyright 2022 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 jsontesting
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/google/go-cmp/cmp"
+)
+
+type RoundTripTestCase struct {
+	Name   string
+	JSON   string
+	Object json.Marshaler
+
+	// An error that is expected when `Object` is marshalled to json
+	// If `Object` does not exist, then it is inferred from the provided JSON
+	ExpectedMarshalError string
+
+	// An error that is expected when the provided JSON is unmarshalled
+	// If `JSON` does not exist then this it is inferred from the provided `Object`
+	ExpectedUnmarshalError string
+}
+
+func (t RoundTripTestCase) RoundTripTest(example json.Unmarshaler) error {
+	var jsonBytes []byte
+	var err error
+
+	// Tests whether the provided error matches the given pattern, and says
+	// whether the test is finished, and the error to return
+	expectError := func(e error, name string, expected string) (testFinished bool, err error) {
+		if len(expected) > 0 {
+			if e == nil || !strings.Contains(e.Error(), expected) {
+				return true, fmt.Errorf("expected %v error containing substring: '%s'. but got actual error '%v'", name, expected, e)
+			}
+
+			// If an error was expected and achieved, we stop the test
+			// since it cannot be continued. But the return nil error since it
+			// was expected.
+			return true, nil
+		} else if e != nil {
+			return true, fmt.Errorf("unexpected %v error: %w", name, e)
+		}
+
+		return false, nil
+	}
+
+	// If user did not provide JSON and instead provided Object, infer JSON
+	// from the provided object.
+	if len(t.JSON) == 0 {
+		jsonBytes, err = json.Marshal(t.Object)
+		if testFinished, err := expectError(err, "marshal", t.ExpectedMarshalError); testFinished {
+			return err
+		}
+	} else {
+		jsonBytes = []byte(t.JSON)
+	}
+
+	err = example.UnmarshalJSON(jsonBytes)
+	if testFinished, err := expectError(err, "unmarshal", t.ExpectedUnmarshalError); testFinished {
+		return err
+	}
+
+	if t.Object != nil && !reflect.DeepEqual(t.Object, example) {
+		return fmt.Errorf("test case expected to unmarshal to specific value: %v", cmp.Diff(t.Object, example))
+	}
+
+	reEncoded, err := json.MarshalIndent(example, "", "    ")
+	if err != nil {
+		return fmt.Errorf("failed to marshal decoded value: %w", err)
+	}
+
+	// Check expected marshal error if it has not yet been checked
+	// (for case where JSON is provided, and object is not)
+	if testFinished, err := expectError(err, "marshal", t.ExpectedMarshalError); testFinished {
+		return err
+	}
+	// Marshal both re-encoded, and original JSON into interface
+	// to compare them without ordering issues
+	var expected map[string]interface{}
+	var actual map[string]interface{}
+
+	if err = json.Unmarshal(jsonBytes, &expected); err != nil {
+		return fmt.Errorf("failed to unmarshal test json: %w", err)
+	}
+
+	if err = json.Unmarshal(reEncoded, &actual); err != nil {
+		return fmt.Errorf("failed to unmarshal actual data: %w", err)
+	}
+
+	if !reflect.DeepEqual(expected, actual) {
+		return fmt.Errorf("expected equal values: %v", cmp.Diff(expected, actual))
+	}
+
+	return nil
+}

pkg/validation/spec/header_test.go

@@ -22,6 +22,7 @@ import (
 	"github.com/google/go-cmp/cmp"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	jsontesting "k8s.io/kube-openapi/pkg/util/jsontesting"
 )
 
 func float64Ptr(f float64) *float64 {
@@ -118,3 +119,43 @@ func TestHeaderSerialization(t *testing.T) {
 		t.Fatal(cmp.Diff(header, goodJSONActual, swaggerDiffOptions...))
 	}
 }
+
+func TestHeaderRoundTrip(t *testing.T) {
+	cases := []jsontesting.RoundTripTestCase{
+		{
+			// Show at least one field from each embededd struct sitll allows
+			// roundtrips successfully
+			Name: "UnmarshalEmbedded",
+			JSON: `{
+				"pattern": "x-^",
+				"type": "string",
+				"x-framework": "swagger-go",
+				"description": "the description of this header"
+			  }`,
+			Object: &Header{
+				CommonValidations{
+					Pattern: "x-^",
+				},
+				SimpleSchema{
+					Type: "string",
+				},
+				VendorExtensible{Extensions{
+					"x-framework": "swagger-go",
+				}},
+				HeaderProps{
+					Description: "the description of this header",
+				},
+			},
+		}, {
+			Name:   "BasicCase",
+			JSON:   headerJSON,
+			Object: &header,
+		},
+	}
+
+	for _, tcase := range cases {
+		t.Run(tcase.Name, func(t *testing.T) {
+			require.NoError(t, tcase.RoundTripTest(&Header{}))
+		})
+	}
+}

pkg/validation/spec/info_test.go

@@ -19,6 +19,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	jsontesting "k8s.io/kube-openapi/pkg/util/jsontesting"
 )
 
 const infoJSON = `{
@@ -68,3 +70,35 @@ func TestIntegrationInfo_Deserialize(t *testing.T) {
 		assert.EqualValues(t, info, actual)
 	}
 }
+
+func TestInfoRoundTrip(t *testing.T) {
+	cases := []jsontesting.RoundTripTestCase{
+		{
+			// Show at least one field from each embededd struct sitll allows
+			// roundtrips successfully
+			Name: "UnmarshalEmbedded",
+			JSON: `{
+				"x-framework": "swagger-go",
+				"description": "the description of this object"
+			  }`,
+			Object: &Info{
+				VendorExtensible{Extensions{
+					"x-framework": "swagger-go",
+				}},
+				InfoProps{
+					Description: "the description of this object",
+				},
+			},
+		}, {
+			Name:   "BasicCase",
+			JSON:   infoJSON,
+			Object: &info,
+		},
+	}
+
+	for _, tcase := range cases {
+		t.Run(tcase.Name, func(t *testing.T) {
+			require.NoError(t, tcase.RoundTripTest(&Info{}))
+		})
+	}
+}

pkg/validation/spec/items_test.go

@@ -19,6 +19,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	jsontesting "k8s.io/kube-openapi/pkg/util/jsontesting"
 )
 
 var items = Items{
@@ -79,3 +81,41 @@ func TestIntegrationItems(t *testing.T) {
 
 	assertParsesJSON(t, itemsJSON, items)
 }
+
+func TestItemsRoundTrip(t *testing.T) {
+	cases := []jsontesting.RoundTripTestCase{
+		{
+			// Show at least one field from each embededd struct sitll allows
+			// roundtrips successfully
+			Name: "UnmarshalEmbedded",
+			JSON: `{
+				"$ref": "/components/my.cool.Schema",
+				"pattern": "x-^",
+				"type": "string",
+				"x-framework": "swagger-go"
+			  }`,
+			Object: &Items{
+				Refable{MustCreateRef("/components/my.cool.Schema")},
+				CommonValidations{
+					Pattern: "x-^",
+				},
+				SimpleSchema{
+					Type: "string",
+				},
+				VendorExtensible{Extensions{
+					"x-framework": "swagger-go",
+				}},
+			},
+		}, {
+			Name:   "BasicCase",
+			JSON:   itemsJSON,
+			Object: &items,
+		},
+	}
+
+	for _, tcase := range cases {
+		t.Run(tcase.Name, func(t *testing.T) {
+			require.NoError(t, tcase.RoundTripTest(&Items{}))
+		})
+	}
+}

pkg/validation/spec/operation_test.go

@@ -19,6 +19,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	jsontesting "k8s.io/kube-openapi/pkg/util/jsontesting"
 )
 
 var operation = Operation{
@@ -83,3 +85,35 @@ func TestIntegrationOperation(t *testing.T) {
 
 	assertParsesJSON(t, operationJSON, operation)
 }
+
+func TestOperationRoundtrip(t *testing.T) {
+	cases := []jsontesting.RoundTripTestCase{
+		{
+			// Show at least one field from each embededd struct sitll allows
+			// roundtrips successfully
+			Name: "UnmarshalEmbedded",
+			JSON: `{
+				"description": "a cool description",
+				"x-framework": "swagger-go"
+			  }`,
+			Object: &Operation{
+				VendorExtensible{Extensions{
+					"x-framework": "swagger-go",
+				}},
+				OperationProps{
+					Description: "a cool description",
+				},
+			},
+		}, {
+			Name:   "BasicCase",
+			JSON:   operationJSON,
+			Object: &operation,
+		},
+	}
+
+	for _, tcase := range cases {
+		t.Run(tcase.Name, func(t *testing.T) {
+			require.NoError(t, tcase.RoundTripTest(&Operation{}))
+		})
+	}
+}

pkg/validation/spec/parameters_test.go

@@ -19,6 +19,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	jsontesting "k8s.io/kube-openapi/pkg/util/jsontesting"
 )
 
 var parameter = Parameter{
@@ -97,3 +99,45 @@ func TestIntegrationParameter(t *testing.T) {
 
 	assertParsesJSON(t, parameterJSON, parameter)
 }
+
+func TestParameterRoundtrip(t *testing.T) {
+	cases := []jsontesting.RoundTripTestCase{
+		{
+			// Show at least one field from each embededd struct sitll allows
+			// roundtrips successfully
+			Name: "UnmarshalEmbedded",
+			JSON: `{
+				"$ref": "/components/ref/to/something.foo",
+				"maxLength": 100,
+				"type": "string",
+				"x-framework": "swagger-go",
+				"description": "a really cool description"
+			  }`,
+			Object: &Parameter{
+				Refable{MustCreateRef("/components/ref/to/something.foo")},
+				CommonValidations{
+					MaxLength: int64Ptr(100),
+				},
+				SimpleSchema{
+					Type: "string",
+				},
+				VendorExtensible{Extensions{
+					"x-framework": "swagger-go",
+				}},
+				ParamProps{
+					Description: "a really cool description",
+				},
+			},
+		}, {
+			Name:   "BasicCase",
+			JSON:   parameterJSON,
+			Object: &parameter,
+		},
+	}
+
+	for _, tcase := range cases {
+		t.Run(tcase.Name, func(t *testing.T) {
+			require.NoError(t, tcase.RoundTripTest(&Parameter{}))
+		})
+	}
+}