From c6d7a0bff97f4239873addab53194dbc10d99071 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Do=C4=9Fan=20Can=20Bak=C4=B1r?=
 <dogancanbakir@protonmail.com>
Date: Tue, 30 Jul 2024 15:12:59 +0300
Subject: [PATCH 1/2] introduce safewriter

---
 io/io.go      | 26 ++++++++++++++++++++++++++
 io/io_test.go | 28 ++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)
 create mode 100644 io/io.go
 create mode 100644 io/io_test.go

diff --git a/io/io.go b/io/io.go
new file mode 100644
index 0000000..9aef945
--- /dev/null
+++ b/io/io.go
@@ -0,0 +1,26 @@
+package ioutil
+
+import (
+	"io"
+	"sync"
+)
+
+type SafeWriter struct {
+	writer io.Writer
+	mutex  sync.Mutex
+}
+
+func NewSafeWriter(writer io.Writer) *SafeWriter {
+	return &SafeWriter{
+		writer: writer,
+	}
+}
+
+func (sw *SafeWriter) Write(p []byte) (n int, err error) {
+	sw.mutex.Lock()
+	defer sw.mutex.Unlock()
+	if sw.writer == nil {
+		return 0, io.ErrClosedPipe
+	}
+	return sw.writer.Write(p)
+}
diff --git a/io/io_test.go b/io/io_test.go
new file mode 100644
index 0000000..c34135f
--- /dev/null
+++ b/io/io_test.go
@@ -0,0 +1,28 @@
+package ioutil
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestSafeWriter(t *testing.T) {
+	t.Run("success", func(t *testing.T) {
+		var sb strings.Builder
+		sw := NewSafeWriter(&sb)
+		_, err := sw.Write([]byte("test"))
+		if err != nil {
+			t.Fatalf("expected no error, got %v", err)
+		}
+		if sb.String() != "test" {
+			t.Fatalf("expected 'test', got '%s'", sb.String())
+		}
+	})
+
+	t.Run("failure", func(t *testing.T) {
+		sw := NewSafeWriter(nil)
+		_, err := sw.Write([]byte("test"))
+		if err == nil {
+			t.Fatalf("expected error, got nil")
+		}
+	})
+}

From 5fba4efc1ed6913c1d50a5d8e65a126379134bdf Mon Sep 17 00:00:00 2001
From: Mzack9999 <mzack9999@protonmail.com>
Date: Tue, 30 Jul 2024 15:18:44 +0200
Subject: [PATCH 2/2] moving error to new

---
 io/io.go      | 20 ++++++++++++++++----
 io/io_test.go | 23 ++++++++++-------------
 2 files changed, 26 insertions(+), 17 deletions(-)

diff --git a/io/io.go b/io/io.go
index 9aef945..4ea74ad 100644
--- a/io/io.go
+++ b/io/io.go
@@ -1,24 +1,36 @@
 package ioutil
 
 import (
+	"errors"
 	"io"
 	"sync"
 )
 
+// SafeWriter is a thread-safe wrapper for io.Writer
 type SafeWriter struct {
-	writer io.Writer
-	mutex  sync.Mutex
+	writer io.Writer   // The underlying writer
+	mutex  *sync.Mutex // Mutex for ensuring thread-safety
 }
 
-func NewSafeWriter(writer io.Writer) *SafeWriter {
-	return &SafeWriter{
+// NewSafeWriter creates and returns a new SafeWriter
+func NewSafeWriter(writer io.Writer) (*SafeWriter, error) {
+	// Check if the provided writer is nil
+	if writer == nil {
+		return nil, errors.New("writer is nil")
+	}
+
+	safeWriter := &SafeWriter{
 		writer: writer,
+		mutex:  &sync.Mutex{},
 	}
+	return safeWriter, nil
 }
 
+// Write implements the io.Writer interface in a thread-safe manner
 func (sw *SafeWriter) Write(p []byte) (n int, err error) {
 	sw.mutex.Lock()
 	defer sw.mutex.Unlock()
+
 	if sw.writer == nil {
 		return 0, io.ErrClosedPipe
 	}
diff --git a/io/io_test.go b/io/io_test.go
index c34135f..a40d591 100644
--- a/io/io_test.go
+++ b/io/io_test.go
@@ -3,26 +3,23 @@ package ioutil
 import (
 	"strings"
 	"testing"
+
+	"github.com/stretchr/testify/require"
 )
 
 func TestSafeWriter(t *testing.T) {
 	t.Run("success", func(t *testing.T) {
 		var sb strings.Builder
-		sw := NewSafeWriter(&sb)
-		_, err := sw.Write([]byte("test"))
-		if err != nil {
-			t.Fatalf("expected no error, got %v", err)
-		}
-		if sb.String() != "test" {
-			t.Fatalf("expected 'test', got '%s'", sb.String())
-		}
+		sw, err := NewSafeWriter(&sb)
+		require.Nil(t, err)
+		_, err = sw.Write([]byte("test"))
+		require.Nil(t, err)
+		require.Equal(t, "test", sb.String())
 	})
 
 	t.Run("failure", func(t *testing.T) {
-		sw := NewSafeWriter(nil)
-		_, err := sw.Write([]byte("test"))
-		if err == nil {
-			t.Fatalf("expected error, got nil")
-		}
+		sw, err := NewSafeWriter(nil)
+		require.NotNil(t, err)
+		require.Nil(t, sw)
 	})
 }