after both, actionToFunc (#21)

* try afterBoth

* update after_both

* ActionToFunc

* more tweaks

* remove afterAll, ready to merge to main

* code coverage

* update comments

Author: haitch

after_both.go

@@ -0,0 +1,33 @@
+package asynctask
+
+import "context"
+
+// AfterBothFunc is a function that has 2 input.
+type AfterBothFunc[T, S, R any] func(context.Context, *T, *S) (*R, error)
+
+// AfterBoth runs the function after both 2 input task finished, and will be fed with result from 2 input task.
+//   if one of the input task failed, the AfterBoth task will be failed and returned, even other one are still running.
+func AfterBoth[T, S, R any](ctx context.Context, tskT *Task[T], tskS *Task[S], next AfterBothFunc[T, S, R]) *Task[R] {
+	return Start(ctx, func(fCtx context.Context) (*R, error) {
+		t, err := tskT.Result(fCtx)
+		if err != nil {
+			return nil, err
+		}
+
+		s, err := tskS.Result(fCtx)
+		if err != nil {
+			return nil, err
+		}
+
+		return next(fCtx, t, s)
+	})
+}
+
+// AfterBothActionToFunc convert a Action to Func (C# term), to satisfy the AfterBothFunc interface.
+//   Action is function that runs without return anything
+//   Func is function that runs and return something
+func AfterBothActionToFunc[T, S any](action func(context.Context, *T, *S) error) func(context.Context, *T, *S) (*interface{}, error) {
+	return func(ctx context.Context, t *T, s *S) (*interface{}, error) {
+		return nil, action(ctx, t, s)
+	}
+}

after_both_test.go

@@ -0,0 +1,69 @@
+package asynctask_test
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/Azure/go-asynctask"
+	"github.com/stretchr/testify/assert"
+)
+
+func summarize2CountingTask(ctx context.Context, result1, result2 *int) (*int, error) {
+	t := ctx.Value(testContextKey).(*testing.T)
+	t.Logf("result1: %d", result1)
+	t.Logf("result2: %d", result2)
+	sum := *result1 + *result2
+	t.Logf("sum: %d", sum)
+	return &sum, nil
+}
+
+func TestAfterBoth(t *testing.T) {
+	t.Parallel()
+	ctx := newTestContext(t)
+	t1 := asynctask.Start(ctx, getCountingTask(10, "afterboth.P1", 20*time.Millisecond))
+	t2 := asynctask.Start(ctx, getCountingTask(10, "afterboth.P2", 20*time.Millisecond))
+	t3 := asynctask.AfterBoth(ctx, t1, t2, summarize2CountingTask)
+
+	sum, err := t3.Result(ctx)
+	assert.NoError(t, err)
+	assert.Equal(t, asynctask.StateCompleted, t3.State(), "Task should complete with no error")
+	assert.Equal(t, *sum, 18, "Sum should be 18")
+}
+
+func TestAfterBothFailureCase(t *testing.T) {
+	t.Parallel()
+	ctx := newTestContext(t)
+	errTask := asynctask.Start(ctx, getErrorTask("devide by 0", 10*time.Millisecond))
+	countingTask := asynctask.Start(ctx, getCountingTask(10, "afterboth.P1", 20*time.Millisecond))
+
+	task1Err := asynctask.AfterBoth(ctx, errTask, countingTask, summarize2CountingTask)
+	_, err := task1Err.Result(ctx)
+	assert.Error(t, err)
+
+	task2Err := asynctask.AfterBoth(ctx, errTask, countingTask, summarize2CountingTask)
+	_, err = task2Err.Result(ctx)
+	assert.Error(t, err)
+
+	task3NoErr := asynctask.AfterBoth(ctx, countingTask, countingTask, summarize2CountingTask)
+	_, err = task3NoErr.Result(ctx)
+	assert.NoError(t, err)
+}
+
+func TestAfterBothActionToFunc(t *testing.T) {
+	t.Parallel()
+	ctx := newTestContext(t)
+
+	countingTask1 := asynctask.Start(ctx, getCountingTask(10, "afterboth.P1", 20*time.Millisecond))
+	countingTask2 := asynctask.Start(ctx, getCountingTask(10, "afterboth.P2", 20*time.Millisecond))
+	t2 := asynctask.AfterBoth(ctx, countingTask1, countingTask2, asynctask.AfterBothActionToFunc(func(ctx context.Context, result1, result2 *int) error {
+		t := ctx.Value(testContextKey).(*testing.T)
+		t.Logf("result1: %d", result1)
+		t.Logf("result2: %d", result2)
+		sum := *result1 + *result2
+		t.Logf("sum: %d", sum)
+		return nil
+	}))
+	_, err := t2.Result(ctx)
+	assert.NoError(t, err)
+}

continue_with.go

@@ -14,3 +14,12 @@ func ContinueWith[T any, S any](ctx context.Context, tsk *Task[T], next Continue
 		return next(fCtx, result)
 	})
 }
+
+// ContinueActionToFunc convert a Action to Func (C# term), to satisfy the AsyncFunc interface.
+//   Action is function that runs without return anything
+//   Func is function that runs and return something
+func ContinueActionToFunc[T any](action func(context.Context, *T) error) func(context.Context, *T) (*interface{}, error) {
+	return func(ctx context.Context, t *T) (*interface{}, error) {
+		return nil, action(ctx, t)
+	}
+}

continue_with_test.go

@@ -2,6 +2,7 @@ package asynctask_test
 
 import (
 	"context"
+	"fmt"
 	"testing"
 	"time"
 
@@ -75,3 +76,18 @@ func TestContinueWithFailureCase(t *testing.T) {
 	assert.Equal(t, asynctask.StateFailed, t3.State(), "Task3 should fail since preceeding task failed")
 	assert.Equal(t, "devide by 0", err.Error())
 }
+
+func TestContinueActionToFunc(t *testing.T) {
+	t.Parallel()
+	ctx := newTestContext(t)
+
+	t1 := asynctask.Start(ctx, func(ctx context.Context) (*int, error) { i := 0; return &i, nil })
+	t2 := asynctask.ContinueWith(ctx, t1, asynctask.ContinueActionToFunc(func(ctx context.Context, i *int) error {
+		if *i != 0 {
+			return fmt.Errorf("input should be 0, but got %d", i)
+		}
+		return nil
+	}))
+	_, err := t2.Result(ctx)
+	assert.NoError(t, err)
+}

task.go

@@ -11,6 +11,15 @@ import (
 // AsyncFunc is a function interface this asyncTask accepts.
 type AsyncFunc[T any] func(context.Context) (*T, error)
 
+// ActionToFunc convert a Action to Func (C# term), to satisfy the AsyncFunc interface.
+//   Action is function that runs without return anything
+//   Func is function that runs and return something
+func ActionToFunc(action func(context.Context) error) func(context.Context) (*interface{}, error) {
+	return func(ctx context.Context) (*interface{}, error) {
+		return nil, action(ctx)
+	}
+}
+
 // Task is a handle to the running function.
 // which you can use to wait, cancel, get the result.
 type Task[T any] struct {

task_test.go

@@ -150,6 +150,20 @@ func TestCompletedGenericTask(t *testing.T) {
 	assert.Equal(t, *resultGet, result)
 }
 
+func TestActionToFunc(t *testing.T) {
+	t.Parallel()
+
+	action := func(ctx context.Context) error {
+		return nil
+	}
+
+	ctx := context.Background()
+	task := asynctask.Start(ctx, asynctask.ActionToFunc(action))
+	result, err := task.Result(ctx)
+	assert.NoError(t, err)
+	assert.Nil(t, result)
+}
+
 func TestCrazyCaseGeneric(t *testing.T) {
 	t.Parallel()
 	ctx, cancelFunc := newTestContextWithTimeout(t, 3*time.Second)