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: update_test.go
    path of file: ./repos/fastjson
    
    the code of the file until where you have to start completion: package fastjson

import (
	"testing"
)

func TestObjectDelSet(t *testing.T) {
	var p Parser
	var o *Object

	o.Del("xx")

	v, err := p.Parse(`{"fo\no": "bar", "x": [1,2,3]}`)
	if err != nil {
		t.Fatalf("unexpected error during parse: %s", err)
	}
	o, err = v.Object()
	if err != nil {
		t.Fatalf("cannot obtain object: %s", err)
	}

	//
    
func TestObjectDelSet(t *testing.T) {
	var p Parser
	var o *Object

	o.Del("xx")

	v, err := p.Parse(`{"fo\no": "bar", "x": [1,2,3]}`)
	if err != nil {
		t.Fatalf("unexpected error during parse: %s", err)
	}
	o, err = v.Object()
	if err != nil {
		t.Fatalf("cannot obtain object: %s", err)
	}

	// Delete x
	o.Del("x")
	if o.Len() != 1 {
		t.Fatalf("unexpected number of items left; got %d; want %d", o.Len(), 1)
	}

	// Try deleting non-existing value
	o.Del("xxx")
	if o.Len() != 1 {
		t.Fatalf("unexpected number of items left; got %d; want %d", o.Len(), 1)
	}

	// Set new value
	vNew := MustParse(`{"foo":[1,2,3]}`)
	o.Set("new_key", vNew)

	// Delete item with escaped key
	o.Del("fo\no")
	if o.Len() != 1 {
		t.Fatalf("unexpected number of items left; got %d; want %d", o.Len(), 1)
	}

	str := o.String()
	strExpected := `{"new_key":{"foo":[1,2,3]}}`
	if str != strExpected {
		t.Fatalf("unexpected string representation for o: got %q; want %q", str, strExpected)
	}

	// Set and Del function as no-op on nil value
	o = nil
	o.Del("x")
	o.Set("x", MustParse(`[3]`))
}