chore: import upstream snapshot with attribution

api/concurrent/concurrent_test.go

@@ -0,0 +1,149 @@
+package concurrent
+
+import (
+	"context"
+	"errors"
+	"sync/atomic"
+	"testing"
+	"testing/synctest"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestRun_AllSucceed(t *testing.T) {
+	t.Parallel()
+
+	fn1 := func(ctx context.Context) (any, error) { return "one", nil }
+	fn2 := func(ctx context.Context) (any, error) { return "two", nil }
+	fn3 := func(ctx context.Context) (any, error) { return "three", nil }
+
+	results, err := Run(t.Context(), 0, fn1, fn2, fn3)
+
+	require.NoError(t, err)
+	require.Len(t, results, 3)
+
+	values := make([]string, 0, len(results))
+	for _, r := range results {
+		values = append(values, r.Result.(string))
+	}
+	require.ElementsMatch(t, []string{"one", "two", "three"}, values)
+}
+
+func TestRun_OneError(t *testing.T) {
+	t.Parallel()
+
+	sentinel := errors.New("task failed")
+
+	fn1 := func(ctx context.Context) (any, error) { return "ok", nil }
+	fn2 := func(ctx context.Context) (any, error) { return nil, sentinel }
+
+	_, err := Run(t.Context(), 0, fn1, fn2)
+
+	require.ErrorIs(t, err, sentinel)
+}
+
+func TestRun_NoTasks(t *testing.T) {
+	t.Parallel()
+
+	results, err := Run(t.Context(), 0)
+
+	require.NoError(t, err)
+	require.Empty(t, results)
+}
+
+func TestRun_MaxConcurrency(t *testing.T) {
+	t.Parallel()
+
+	const numTasks = 10
+	var peak atomic.Int32
+	var active atomic.Int32
+
+	task := func(ctx context.Context) (any, error) {
+		current := active.Add(1)
+		if current > peak.Load() {
+			peak.Store(current)
+		}
+
+		time.Sleep(10 * time.Millisecond)
+		active.Add(-1)
+
+		return nil, nil
+	}
+
+	tasks := make([]Func, numTasks)
+	for i := range tasks {
+		tasks[i] = task
+	}
+
+	synctest.Test(t, func(t *testing.T) {
+		results, err := Run(t.Context(), 3, tasks...)
+		require.NoError(t, err)
+		require.Len(t, results, numTasks)
+		require.LessOrEqual(t, peak.Load(), int32(3))
+	})
+}
+
+func TestRun_ZeroConcurrencyUsesAllTasks(t *testing.T) {
+	t.Parallel()
+
+	const numTasks = 5
+	var peak atomic.Int32
+	var active atomic.Int32
+
+	task := func(ctx context.Context) (any, error) {
+		current := active.Add(1)
+		if current > peak.Load() {
+			peak.Store(current)
+		}
+
+		time.Sleep(20 * time.Millisecond)
+		active.Add(-1)
+
+		return nil, nil
+	}
+
+	tasks := make([]Func, numTasks)
+	for i := range tasks {
+		tasks[i] = task
+	}
+
+	synctest.Test(t, func(t *testing.T) {
+		results, err := Run(t.Context(), 0, tasks...)
+		require.NoError(t, err)
+		require.Len(t, results, numTasks)
+		require.Equal(t, int32(numTasks), peak.Load())
+	})
+}
+
+func TestRun_ContextCancelledBeforeStart(t *testing.T) {
+	t.Parallel()
+
+	ctx, cancel := context.WithCancel(t.Context())
+	cancel()
+
+	called := atomic.Bool{}
+	fn := func(ctx context.Context) (any, error) {
+		called.Store(true)
+		return nil, ctx.Err()
+	}
+
+	_, err := Run(ctx, 1, fn, fn, fn)
+	require.Error(t, err)
+}
+
+func TestRun_ContextPassedToTasks(t *testing.T) {
+	t.Parallel()
+
+	type key struct{}
+	ctx := context.WithValue(t.Context(), key{}, "testvalue")
+
+	fn := func(ctx context.Context) (any, error) {
+		return ctx.Value(key{}), nil
+	}
+
+	results, err := Run(ctx, 0, fn)
+
+	require.NoError(t, err)
+	require.Equal(t, "testvalue", results[0].Result)
+}