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: format_test.go
    path of file: ./repos/gccrs/libgo/go/go/format
    
    the code of the file until where you have to start completion: // Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package format

import (
	"bytes"
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"strings"
	"testing"
)

const testfile =
    
func TestNodeNoModify(t *testing.T) {
	const (
		src    = "package p\n\nconst _ = 0000000123i\n"
		golden = "package p\n\nconst _ = 123i\n"
	)

	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "", src, parser.ParseComments)
	if err != nil {
		t.Fatal(err)
	}

	// Capture original address and value of a BasicLit node
	// which will undergo formatting changes during printing.
	wantLit := file.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Values[0].(*ast.BasicLit)
	wantVal := wantLit.Value

	var buf bytes.Buffer
	if err = Node(&buf, fset, file); err != nil {
		t.Fatal("Node failed:", err)
	}
	diff(t, buf.Bytes(), []byte(golden))

	// Check if anything changed after Node returned.
	gotLit := file.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec).Values[0].(*ast.BasicLit)
	gotVal := gotLit.Value

	if gotLit != wantLit {
		t.Errorf("got *ast.BasicLit address %p, want %p", gotLit, wantLit)
	}
	if gotVal != wantVal {
		t.Errorf("got *ast.BasicLit value %q, want %q", gotVal, wantVal)
	}
}