safegroup_test.go

// Copyright 2016 The Go Authors. All rights reserved.
// Copyright 2024 Volodymyr Kucherenko <kucherenkovova@gmail.com>. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package safegroup_test

import (
	"context"
	"errors"
	"fmt"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	"github.com/kucherenkovova/safegroup"
)

func TestZeroGroup(t *testing.T) {
	t.Parallel()
	err1 := errors.New("safegroup_test: 1")
	err2 := errors.New("safegroup_test: 2")

	cases := []struct {
		errs []error
	}{
		{errs: []error{}},
		{errs: []error{nil}},
		{errs: []error{err1}},
		{errs: []error{err1, nil}},
		{errs: []error{err1, nil, err2}},
	}

	for _, tc := range cases {
		g := new(safegroup.Group)

		var firstErr error
		for i, err := range tc.errs {
			err := err
			g.Go(func() error { return err })

			if firstErr == nil && err != nil {
				firstErr = err
			}

			if gErr := g.Wait(); gErr != firstErr {
				t.Errorf("after %T.Go(func() error { return err }) for err in %v\n"+
					"g.Wait() = %v; want %v",
					g, tc.errs[:i+1], err, firstErr)
			}
		}
	}
}

func TestWithContext(t *testing.T) {
	t.Parallel()
	errDoom := errors.New("group_test: doomed")

	cases := []struct {
		errs []error
		want error
	}{
		{want: nil},
		{errs: []error{nil}, want: nil},
		{errs: []error{errDoom}, want: errDoom},
		{errs: []error{errDoom, nil}, want: errDoom},
	}

	for _, tc := range cases {
		g, ctx := safegroup.WithContext(context.Background())

		for _, err := range tc.errs {
			err := err
			g.Go(func() error { return err })
		}

		if err := g.Wait(); err != tc.want {
			t.Errorf("after %T.Go(func() error { return err }) for err in %v\n"+
				"g.Wait() = %v; want %v",
				g, tc.errs, err, tc.want)
		}

		canceled := false
		select {
		case <-ctx.Done():
			canceled = true
		default:
		}
		if !canceled {
			t.Errorf("after %T.Go(func() error { return err }) for err in %v\n"+
				"ctx.Done() was not closed",
				g, tc.errs)
		}
	}
}

func TestTryGo(t *testing.T) {
	t.Parallel()
	g := &safegroup.Group{}
	n := 42
	g.SetLimit(42)
	ch := make(chan struct{})
	fn := func() error {
		ch <- struct{}{}
		return nil
	}
	for i := 0; i < n; i++ {
		if !g.TryGo(fn) {
			t.Fatalf("TryGo should succeed but got fail at %d-th call.", i)
		}
	}
	if g.TryGo(fn) {
		t.Fatalf("TryGo is expected to fail but succeeded.")
	}
	go func() {
		for i := 0; i < n; i++ {
			<-ch
		}
	}()
	g.Wait()

	if !g.TryGo(fn) {
		t.Fatalf("TryGo should success but got fail after all goroutines.")
	}
	go func() { <-ch }()
	g.Wait()

	// Switch limit.
	g.SetLimit(1)
	if !g.TryGo(fn) {
		t.Fatalf("TryGo should success but got failed.")
	}
	if g.TryGo(fn) {
		t.Fatalf("TryGo should fail but succeeded.")
	}
	go func() { <-ch }()
	g.Wait()

	// Block all calls.
	g.SetLimit(0)
	for i := 0; i < 1<<10; i++ {
		if g.TryGo(fn) {
			t.Fatalf("TryGo should fail but got succeeded.")
		}
	}
	g.Wait()
}

func TestGoLimit(t *testing.T) {
	t.Parallel()
	const limit = 10

	g := &safegroup.Group{}
	g.SetLimit(limit)
	var active int32
	for i := 0; i <= 1<<10; i++ {
		g.Go(func() error {
			n := atomic.AddInt32(&active, 1)
			if n > limit {
				return fmt.Errorf("saw %d active goroutines; want ≤ %d", n, limit)
			}
			time.Sleep(1 * time.Microsecond) // Give other goroutines a chance to increment active.
			atomic.AddInt32(&active, -1)
			return nil
		})
	}
	if err := g.Wait(); err != nil {
		t.Fatal(err)
	}
}

func BenchmarkGo(b *testing.B) {
	fn := func() {}
	g := &safegroup.Group{}
	b.ResetTimer()
	b.ReportAllocs()
	for i := 0; i < b.N; i++ {
		g.Go(func() error { fn(); return nil })
	}
	g.Wait()
}

func TestSafeGroupHandlesPanic(t *testing.T) {
	t.Parallel()
	g := new(safegroup.Group)
	var urls = []string{
		"http://www.golang.org/",
		"http://www.google.com/",
		"http://www.somestupidname.com/",
	}
	for _, url := range urls {
		url := url
		g.Go(func() error {
			if strings.Contains(url, "google") {
				panic("something went wrong")
			}
			return nil
		})
	}

	err := g.Wait()
	if err == nil {
		t.Fatal("expected error, got nil")
	}
	if !errors.Is(err, safegroup.ErrPanic) {
		t.Fatalf("expected %s, got %s", safegroup.ErrPanic, err)
	}
}