🔥 Feature: Add thread-safe reading from a closed testConn

helpers.go

@@ -613,13 +613,36 @@ func isNoCache(cacheControl string) bool {
 }
 
 type testConn struct {
-	r bytes.Buffer
-	w bytes.Buffer
+	r        bytes.Buffer
+	w        bytes.Buffer
+	isClosed bool
+	sync.Mutex
 }
 
-func (c *testConn) Read(b []byte) (int, error)  { return c.r.Read(b) }  //nolint:wrapcheck // This must not be wrapped
-func (c *testConn) Write(b []byte) (int, error) { return c.w.Write(b) } //nolint:wrapcheck // This must not be wrapped
-func (*testConn) Close() error                  { return nil }
+func (c *testConn) Read(b []byte) (int, error) {
+	c.Lock()
+	defer c.Unlock()
+
+	return c.r.Read(b) //nolint:wrapcheck // This must not be wrapped
+}
+
+func (c *testConn) Write(b []byte) (int, error) {
+	c.Lock()
+	defer c.Unlock()
+
+	if c.isClosed {
+		return 0, errors.New("testConn is closed")
+	}
+	return c.w.Write(b) //nolint:wrapcheck // This must not be wrapped
+}
+
+func (c *testConn) Close() error {
+	c.Lock()
+	defer c.Unlock()
+
+	c.isClosed = true
+	return nil
+}
 
 func (*testConn) LocalAddr() net.Addr                { return &net.TCPAddr{Port: 0, Zone: "", IP: net.IPv4zero} }
 func (*testConn) RemoteAddr() net.Addr               { return &net.TCPAddr{Port: 0, Zone: "", IP: net.IPv4zero} }

helpers_test.go

@@ -5,6 +5,7 @@
 package fiber
 
 import (
+	"errors"
 	"strings"
 	"testing"
 	"time"
@@ -514,6 +515,23 @@ func Test_Utils_TestConn_Deadline(t *testing.T) {
 	require.NoError(t, conn.SetWriteDeadline(time.Time{}))
 }
 
+func Test_Utils_TestConn_Closed_Write(t *testing.T) {
+	t.Parallel()
+	conn := &testConn{}
+
+	_, err := conn.Write([]byte("Hello World"))
+	require.NoError(t, err)
+
+	conn.Close()
+	_, err = conn.Write([]byte("This should fail"))
+	require.ErrorIs(t, err, errors.New("testConn is closed"))
+
+	buffer := make([]byte, 12)
+	_, err = conn.Read(buffer)
+	require.NoError(t, err)
+	require.Equal(t, []byte("Hello World"), buffer)
+}
+
 func Test_Utils_IsNoCache(t *testing.T) {
 	t.Parallel()
 	testCases := []struct {