Merge pull request #883 from xmlking/master

PatchContext method added

metadata/metadata.go

@@ -28,3 +28,20 @@ func FromContext(ctx context.Context) (Metadata, bool) {
 func NewContext(ctx context.Context, md Metadata) context.Context {
 	return context.WithValue(ctx, metaKey{}, md)
 }
+
+func AppendContext(ctx context.Context, patchMd Metadata, overwrite bool) context.Context {
+	md, _ := ctx.Value(metaKey{}).(Metadata)
+	cmd := make(Metadata)
+	for k, v := range md {
+		cmd[k] = v
+	}
+	for k, v := range patchMd {
+		if _, ok := cmd[k]; ok && !overwrite {
+			// skip
+		} else {
+			cmd[k] = v
+		}
+	}
+	return context.WithValue(ctx, metaKey{}, cmd)
+
+}

metadata/metadata_test.go

@@ -2,6 +2,7 @@ package metadata
 
 import (
 	"context"
+	"reflect"
 	"testing"
 )
 
@@ -40,3 +41,42 @@ func TestMetadataContext(t *testing.T) {
 		t.Errorf("Expected metadata length 1 got %d", i)
 	}
 }
+
+func TestAppendContext(t *testing.T) {
+	type args struct {
+		existing  Metadata
+		append    Metadata
+		overwrite bool
+	}
+	tests := []struct {
+		name string
+		args args
+		want Metadata
+	}{
+		{
+			name: "matching key, overwrite false",
+			args: args{
+				existing:  Metadata{"foo": "bar", "sumo": "demo"},
+				append:    Metadata{"sumo": "demo2"},
+				overwrite: false,
+			},
+			want: Metadata{"foo": "bar", "sumo": "demo"},
+		},
+		{
+			name: "matching key, overwrite true",
+			args: args{
+				existing:  Metadata{"foo": "bar", "sumo": "demo"},
+				append:    Metadata{"sumo": "demo2"},
+				overwrite: true,
+			},
+			want: Metadata{"foo": "bar", "sumo": "demo2"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got, _ := FromContext(AppendContext(NewContext(context.TODO(), tt.args.existing), tt.args.append, tt.args.overwrite)); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("AppendContext() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}