go-livecoding-interview/executor_test.go at main · MrREN73/go-livecoding-interview · GitHub

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package main

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

	"github.com/stretchr/testify/require"
	"go.uber.org/goleak"
)

func TestExecuteOrder(t *testing.T) {
	tasks := []Task{
		func(ctx context.Context) (Result, error) {
			time.Sleep(300 * time.Millisecond)
			return 1, nil
		},
		func(ctx context.Context) (Result, error) {
			time.Sleep(100 * time.Millisecond)
			return 2, nil
		},
		func(ctx context.Context) (Result, error) {
			time.Sleep(200 * time.Millisecond)
			return 3, nil
		},
	}

	results, err := Execute(context.Background(), 3, tasks)

	require.NoError(t, err)
	require.Equal(t, []Result{1, 2, 3}, results)
}

func TestExecuteErrorCancels(t *testing.T) {
	cancelled := atomic.Int32{}

	tasks := []Task{
		func(ctx context.Context) (Result, error) {
			time.Sleep(100 * time.Millisecond)
			return nil, errors.New("boom")
		},

		func(ctx context.Context) (Result, error) {
			select {
			case <-ctx.Done():
				cancelled.Add(1)
				return nil, ctx.Err()
			case <-time.After(5 * time.Second):
				return "finished", nil
			}
		},

		func(ctx context.Context) (Result, error) {
			select {
			case <-ctx.Done():
				cancelled.Add(1)
				return nil, ctx.Err()
			case <-time.After(5 * time.Second):
				return "finished", nil
			}
		},
	}

	_, err := Execute(context.Background(), 3, tasks)

	require.Error(t, err)
	require.EqualError(t, err, "boom")

	require.Equal(t, int32(2), cancelled.Load())
}

func TestExecuteWorkerLimit(t *testing.T) {
	var running atomic.Int32
	var maxRunning atomic.Int32

	tasks := make([]Task, 50)

	for i := range tasks {
		tasks[i] = func(ctx context.Context) (Result, error) {
			current := running.Add(1)

			for {

				old := maxRunning.Load()

				if current <= old {
					break
				}

				if maxRunning.CompareAndSwap(old, current) {
					break
				}
			}

			time.Sleep(100 * time.Millisecond)

			running.Add(-1)

			return nil, nil
		}
	}

	_, err := Execute(context.Background(), 5, tasks)

	require.NoError(t, err)

	require.Equal(t, int32(5), maxRunning.Load())
}

func TestMain(m *testing.M) {
	goleak.VerifyTestMain(m)
}

func TestExecuteNoLeaks(t *testing.T) {
	tasks := make([]Task, 100)

	for i := range tasks {
		tasks[i] = func(ctx context.Context) (Result, error) {
			time.Sleep(10 * time.Millisecond)

			return nil, nil
		}
	}

	_, err := Execute(context.Background(), 10, tasks)

	require.NoError(t, err)
}