fix tests

errors.go

@@ -78,7 +78,7 @@ type Builder interface {
 	Build() *WithStackInfo
 
 	// Attach inner errors for backward compatibility to v2
-	Attach(errs ...error)
+	Attach(errs ...error) *WithStackInfo
 }
 
 type builder struct {
@@ -100,8 +100,8 @@ func (s *builder) WithErrors(errs ...error) Builder {
 
 // Attach attaches the given errs as inner errors.
 // For backward compatibility to v2
-func (s *builder) Attach(errs ...error) {
-	_ = s.WithErrors(errs...).Build()
+func (s *builder) Attach(errs ...error) *WithStackInfo {
+	return s.WithErrors(errs...).Build()
 }
 
 // WithMessage formats the error message

errors_test.go

@@ -30,6 +30,13 @@ func TestNew(t *testing.T) {
 		Build()
 	t.Logf("failed: %+v", err)
 
+	err = NewBuilder().
+		WithCode(Internal).
+		WithErrors(io.EOF).
+		WithErrors(io.ErrShortWrite).
+		Attach(io.ErrClosedPipe)
+	t.Logf("failed: %+v", err)
+
 	err = New(WithErrors(io.EOF, io.ErrShortWrite))
 	t.Logf("failed: %+v", err)
 

withstackinfo.go

@@ -146,6 +146,12 @@ func (w *WithStackInfo) Defer(err *error) {
 	*err = w
 }
 
+// Attach _
+func (w *WithStackInfo) Attach(errs ...error) *WithStackInfo {
+	_ = w.WithErrors(errs...)
+	return w
+}
+
 // Format formats the stack of Frames according to the fmt.Formatter interface.
 //
 //    %s	lists source files for each Frame in the stack