From 02e52b689e83ae4359356bd84d7f905e2c557acd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Sandro=20J=C3=A4ckel?= <sandro.jaeckel@sap.com>
Date: Wed, 17 Apr 2024 14:46:48 +0200
Subject: [PATCH] Add helper to compare gopk.in/yaml.v{2,3}

---
 go.mod       |   1 +
 yaml/yaml.go | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 105 insertions(+)
 create mode 100644 yaml/yaml.go

diff --git a/go.mod b/go.mod
index 1fe718c..e766cc6 100644
--- a/go.mod
+++ b/go.mod
@@ -6,6 +6,7 @@ require (
 	github.com/databus23/goslo.policy v0.0.0-20210929125152-81bf2876dbdb
 	github.com/gofrs/uuid/v5 v5.1.0
 	github.com/golang-migrate/migrate/v4 v4.17.0
+	github.com/google/go-cmp v0.6.0
 	github.com/gophercloud/gophercloud v1.11.0
 	github.com/gorilla/mux v1.8.1
 	github.com/hashicorp/golang-lru/v2 v2.0.7
diff --git a/yaml/yaml.go b/yaml/yaml.go
new file mode 100644
index 0000000..bc516e1
--- /dev/null
+++ b/yaml/yaml.go
@@ -0,0 +1,104 @@
+/*******************************************************************************
+*
+* Copyright 2024 SAP SE
+*
+* Licensed under the Apache License, Version 2.0 (the "License");
+* you may not use this file except in compliance with the License.
+* You should have received a copy of the License along with this
+* program. If not, 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.
+*
+*******************************************************************************/
+
+// This package is just an aid to migrate from gopkg.in/yaml.v2 to gopkg.in/yaml.v2
+// It provides a helper to parse a given yaml document with both major versions and log if there is a difference.
+package yaml
+
+import (
+	"bytes"
+	"fmt"
+	"reflect"
+
+	"github.com/google/go-cmp/cmp"
+	yaml_v2 "gopkg.in/yaml.v2"
+	yaml_v3 "gopkg.in/yaml.v3"
+
+	"github.com/sapcc/go-bits/logg"
+)
+
+func Marshal[T any](in T) ([]byte, error) {
+	out, err := yaml_v2.Marshal(in)
+	if err != nil {
+		return nil, err
+	}
+
+	outV3 := new(bytes.Buffer)
+	dec := yaml_v3.NewEncoder(outV3)
+	dec.SetIndent(2)
+	err = dec.Encode(in)
+	if err != nil {
+		logg.Error("gopkg.in/yaml.v3.Marshal() returned an error: %w,", err)
+	}
+
+	if !reflect.DeepEqual(out, outV3.Bytes()) {
+		logg.Error("gopkg.in/yaml.v2 and gopkg.in/yaml.v3 Marshal() are not equal. Turn on debug logging to see the difference.")
+		if logg.ShowDebug {
+			fmt.Print(cmp.Diff(out, outV3.Bytes()))
+		}
+	}
+
+	return out, nil
+}
+
+func Unmarshal[T any](in []byte, out *T) error {
+	err := yaml_v2.Unmarshal(in, out)
+	if err != nil {
+		return err
+	}
+
+	var outV3 *T
+	err = yaml_v3.Unmarshal(in, outV3)
+	if err != nil {
+		logg.Error("gopkg.in/yaml.v3.Unmarshal() returned an error: %w,", err)
+	}
+
+	if !reflect.DeepEqual(out, outV3) {
+		logg.Error("gopkg.in/yaml.v2 and gopkg.in/yaml.v3 Unmarshal() are not equal. Turn on debug logging to see the difference.")
+		if logg.ShowDebug {
+			fmt.Print(cmp.Diff(out, outV3))
+		}
+	}
+
+	return nil
+}
+
+func UnmarshalStrict[T any](in []byte, out *T) error {
+	err := yaml_v2.UnmarshalStrict(in, out)
+	if err != nil {
+		return err
+	}
+
+	var outV3 *T
+	dec := yaml_v3.NewDecoder(bytes.NewReader(in))
+	dec.KnownFields(true)
+	err = dec.Decode(&outV3)
+	if err != nil {
+		logg.Error("gopkg.in/yaml.v3.UnmarshalStrict() returned an error: %w,", err)
+	}
+
+	if !reflect.DeepEqual(out, outV3) {
+		logg.Error("gopkg.in/yaml.v2 and gopkg.in/yaml.v3 UnmarshalStrict() are not equal. Turn on debug logging to see the difference.")
+		if logg.ShowDebug {
+			fmt.Print(cmp.Diff(out, outV3))
+		}
+	}
+
+	return nil
+}