You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: metadata_test.go
    path of file: ./repos/kratos/metadata
    
    the code of the file until where you have to start completion: package metadata

import (
	"context"
	"reflect"
	"testing"
)

func TestNew(t *testing.T) {
    
func TestMetadata_Set(t *testing.T) {
	type args struct {
		key   string
		value string
	}
	tests := []struct {
		name string
		m    Metadata
		args args
		want Metadata
	}{
		{
			name: "kratos",
			m:    Metadata{},
			args: args{key: "hello", value: "kratos"},
			want: Metadata{"hello": {"kratos"}},
		},
		{
			name: "env",
			m:    Metadata{"hello": {"kratos"}},
			args: args{key: "env", value: "pro"},
			want: Metadata{"hello": {"kratos"}, "env": {"pro"}},
		},
		{
			name: "empty",
			m:    Metadata{},
			args: args{key: "", value: ""},
			want: Metadata{},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			tt.m.Set(tt.args.key, tt.args.value)
			if !reflect.DeepEqual(tt.m, tt.want) {
				t.Errorf("Set() = %v, want %v", tt.m, tt.want)
			}
		})
	}
}