main_test.2.go

package main

import (
	"bufio"
	"bytes"
	"flag"
	"io/ioutil"
	"path/filepath"
	"testing"
)

var update = flag.Bool("update", false, "update .golden files")

func TestToJSON(t *testing.T) {
	var b bytes.Buffer
	w := bufio.NewWriter(&b)
	err := ToJSON(w)
	if err != nil {
		t.Fatalf("failed writing json: %s", err)
	}
	w.Flush()
	gp := filepath.Join("testdata", t.Name()+".golden")
	if *update {
		t.Log("update golden file")
		if err := ioutil.WriteFile(gp, b.Bytes(), 0644); err != nil {
			t.Fatalf("failed to update golden file: %s", err)
		}
	}
	g, err := ioutil.ReadFile(gp)
	if err != nil {
		t.Fatalf("failed reading .golden: %s", err)
	}
	t.Log(string(b.Bytes()))
	if !bytes.Equal(b.Bytes(), g) {
		t.Errorf("writtein json does not match .golden file")
	}
}