Move metadata to core/metadata

Signed-off-by: Derek McGowan <derek@mcg.dev>

core/metadata/compare_test.go

@@ -0,0 +1,74 @@
+/*
+   Copyright The containerd 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 metadata
+
+import (
+	"bytes"
+	"reflect"
+	"time"
+
+	"github.com/containerd/typeurl/v2"
+	"github.com/google/go-cmp/cmp"
+)
+
+// isNil returns true if the given parameter is nil or typed nil.
+func isNil(x interface{}) bool {
+	if x == nil {
+		return true
+	}
+	v := reflect.ValueOf(x)
+	return v.Kind() == reflect.Ptr && v.IsNil()
+}
+
+var compareNil = cmp.FilterValues(
+	func(x, y interface{}) bool {
+		return isNil(x) && isNil(y)
+	},
+	cmp.Comparer(func(_, _ interface{}) bool {
+		return true
+	}),
+)
+
+var ignoreTime = cmp.FilterValues(
+	func(x, y interface{}) bool {
+		_, xok := x.(time.Time)
+		_, yok := y.(time.Time)
+		return xok && yok
+	},
+	cmp.Comparer(func(_, _ interface{}) bool {
+		return true
+	}),
+)
+
+var compareAny = cmp.FilterValues(
+	func(x, y interface{}) bool {
+		_, xok := x.(typeurl.Any)
+		_, yok := y.(typeurl.Any)
+		return xok && yok
+	},
+	cmp.Comparer(func(x, y interface{}) bool {
+		vx, ok := x.(typeurl.Any)
+		if !ok {
+			return false
+		}
+		vy, ok := y.(typeurl.Any)
+		if !ok {
+			return false
+		}
+		return vx.GetTypeUrl() == vy.GetTypeUrl() && bytes.Equal(vx.GetValue(), vy.GetValue())
+	}),
+)