Small tests of pprof merges being associative. Not exhaustive, but running this multiple times showed no failures.

main_test.go

package main

import (
	"bytes"
	"io/ioutil"
	"math/rand"
	"reflect"
	"testing"
	"time"

	"github.com/google/pprof/profile"
)

func MustParse(profileBytes []byte) *profile.Profile {
	p, err := profile.Parse(bytes.NewBuffer(profileBytes))
	if err != nil {
		panic(err)
	}

	return p
}

func MustReadFile(file string) []byte {
	b, err := ioutil.ReadFile(file)
	if err != nil {
		panic(err)
	}

	return b
}

func TestMergeAssociativity(t *testing.T) {
	profiles := []*profile.Profile{
		MustParse(MustReadFile("1.pb.gz")),
		MustParse(MustReadFile("2.pb.gz")),
		MustParse(MustReadFile("3.pb.gz")),
		MustParse(MustReadFile("4.pb.gz")),
	}

	expected, err := profile.Merge(profiles)
	if err != nil {
		t.Fatal(err)
	}

	rand.Seed(time.Now().UnixNano())
	rand.Shuffle(len(profiles), func(i, j int) { profiles[i], profiles[j] = profiles[j], profiles[i] })

	res, err := profile.Merge(profiles)
	if err != nil {
		t.Fatal(err)
	}

	if !reflect.DeepEqual(expected, res) {
		t.Fatal("Not deep equal")
	}

	rand.Seed(time.Now().UnixNano())
	rand.Shuffle(len(profiles), func(i, j int) { profiles[i], profiles[j] = profiles[j], profiles[i] })

	res, err = profile.Merge([]*profile.Profile{mustMerge(profiles[0:2]), mustMerge(profiles[2:])})
	if err != nil {
		t.Fatal(err)
	}

	if !reflect.DeepEqual(expected, res) {
		t.Fatal("Not deep equal")
	}

	rand.Seed(time.Now().UnixNano())
	rand.Shuffle(len(profiles), func(i, j int) { profiles[i], profiles[j] = profiles[j], profiles[i] })

	res, err = profile.Merge([]*profile.Profile{mustMerge(profiles[0:1]), mustMerge(profiles[1:])})
	if err != nil {
		t.Fatal(err)
	}

	if !reflect.DeepEqual(expected, res) {
		t.Fatal("Not deep equal")
	}

	rand.Seed(time.Now().UnixNano())
	rand.Shuffle(len(profiles), func(i, j int) { profiles[i], profiles[j] = profiles[j], profiles[i] })

	res, err = profile.Merge([]*profile.Profile{mustMerge(profiles[0:3]), mustMerge(profiles[3:])})
	if err != nil {
		t.Fatal(err)
	}

	if !reflect.DeepEqual(expected, res) {
		t.Fatal("Not deep equal")
	}
}

func mustMerge(profiles []*profile.Profile) *profile.Profile {
	p, err := profile.Merge(profiles)
	if err != nil {
		panic(err)
	}
	return p
}