From 52e76231d919d3325be9276eb1caa7cf343c1e5c Mon Sep 17 00:00:00 2001
From: Mohammad Rajabloo <themrsoftware@gmail.com>
Date: Tue, 8 Oct 2024 22:35:20 +0330
Subject: [PATCH] refactor waitGroup chanel in a simpler solution

---
 README.md         | 28 ++++++++++++++++++++++++++++
 waitGroup.go      | 27 ++++++++++-----------------
 waitGroup_test.go | 42 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 80 insertions(+), 17 deletions(-)

diff --git a/README.md b/README.md
index cf32590..907e64f 100644
--- a/README.md
+++ b/README.md
@@ -207,6 +207,34 @@ if err := wg.Wait(); err != nil {
     // oh, something bad happened in one of routines above.
 } 
 ```
+### Turn WaitGroup into a chanel
+```go
+import (
+    "github.com/mrsoftware/errors"
+)
+
+wg := errors.NewWaitGroup() 
+
+wg.Do(func(ctx context.Context) error {
+    return callingHttpClient()
+})
+
+wg.Do(func(ctx context.Context) error {
+    return callingHttpClient()
+})
+
+// this wait until receive something from chanel.
+var err error
+select {
+case err = <-errors.WaitChanel(wg):
+}
+
+if err != nil {
+    // oh, something bad happened in one of the routines above.
+} 
+
+```
+
 
 for mode details, check the [documentation](https://godoc.org/github.com/mrsoftware/errors)
 
diff --git a/waitGroup.go b/waitGroup.go
index cf02bc9..fb6f43b 100644
--- a/waitGroup.go
+++ b/waitGroup.go
@@ -14,7 +14,6 @@ type WaitGroup struct {
 	ctx        context.Context
 	cancel     context.CancelCauseFunc
 	cancelOnce sync.Once
-	wait       chan struct{}
 }
 
 // NewWaitGroup create new WaitGroup.
@@ -36,7 +35,7 @@ func NewWaitGroup(options ...WaitGroupOption) *WaitGroup {
 
 	ctx, cancel := context.WithCancelCause(ops.Ctx)
 
-	return &WaitGroup{options: ops, gch: gch, ctx: ctx, cancel: cancel, wait: make(chan struct{})}
+	return &WaitGroup{options: ops, gch: gch, ctx: ctx, cancel: cancel}
 }
 
 // Context of current waitGroup.
@@ -55,21 +54,6 @@ func (g *WaitGroup) Wait() (err error) {
 
 	defer func() { g.Stop(err) }()
 
-	select {
-	case g.wait <- struct{}{}:
-	default:
-	}
-
-	return g.errors.Err()
-}
-
-// WaitChan is like Wait method but return chanel.
-func (g *WaitGroup) WaitChan() <-chan struct{} {
-	return g.wait
-}
-
-// Err of tasks.
-func (g *WaitGroup) Err() error {
 	return g.errors.Err()
 }
 
@@ -175,3 +159,12 @@ func WaitGroupWithContext(ctx context.Context) WaitGroupOption {
 		g.Ctx = ctx
 	}
 }
+
+// WaitChanel turn WaitGroup Wait method into chanel.
+func WaitChanel(wg *WaitGroup) chan error {
+	wait := make(chan error)
+
+	go func() { wait <- wg.Wait() }()
+
+	return wait
+}
diff --git a/waitGroup_test.go b/waitGroup_test.go
index ea7f425..35a3963 100644
--- a/waitGroup_test.go
+++ b/waitGroup_test.go
@@ -158,6 +158,48 @@ func TestGroup(t *testing.T) {
 	})
 }
 
+func TestWaitChanel(t *testing.T) {
+	t.Run("expect to turn wait into chanel and work", func(t *testing.T) {
+		wg := NewWaitGroup()
+
+		wg.Do(func(ctx context.Context) error {
+			return nil
+		})
+
+		wg.Do(func(ctx context.Context) error {
+			return nil
+		})
+
+		var err error
+		select {
+		case err = <-WaitChanel(wg):
+		}
+
+		assert.Nil(t, err)
+	})
+
+	t.Run("expect to turn wait into chanel and get error (one task is failed)", func(t *testing.T) {
+		wg := NewWaitGroup()
+
+		internalErr := errors.New("some error")
+
+		wg.Do(func(ctx context.Context) error {
+			return nil
+		})
+
+		wg.Do(func(ctx context.Context) error {
+			return internalErr
+		})
+
+		var err error
+		select {
+		case err = <-WaitChanel(wg):
+		}
+
+		assert.Equal(t, NewMultiError(internalErr), err)
+	})
+}
+
 // all below test cases are copied from sync/waitgroup_test.go and transformed to group.
 
 func testWaitGroup(t *testing.T, wg1 *WaitGroup, wg2 *WaitGroup) {