From c6e9d39e7edd67a33a358ede111142d292cee283 Mon Sep 17 00:00:00 2001
From: wbflooksky <52812629+wbflooksky@users.noreply.github.com>
Date: Wed, 19 May 2021 17:37:19 +0800
Subject: [PATCH] feat:

feat func ExistStack(err error) bool:

non-intrusive:
Add a public method to determine if the error has been appended to the stack.
Avoid adding the stack repeatedly for errors.

fix: error method

feat: test ExistStack

add ExistStack test

fix: error variable name

style: optimizing code structure

feat: add test example

style(value): delete func reachable code

style(build): edit format files
---
 errors.go      | 21 +++++++++++++++++++++
 errors_test.go | 20 ++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/errors.go b/errors.go
index 161aea25..d740b8bb 100644
--- a/errors.go
+++ b/errors.go
@@ -106,6 +106,27 @@ func New(message string) error {
 	}
 }
 
+// ExistStack return an error already with stack
+// ExistStack will check all parent error
+func ExistStack(err error) bool {
+	type stackTracer interface {
+		StackTrace() StackTrace
+	}
+	_, ok := err.(stackTracer)
+	if ok {
+		return true
+	}
+
+	type causer interface {
+		Cause() error
+	}
+	cause, ok := err.(causer)
+	if !ok {
+		return false
+	}
+	return ExistStack(cause.Cause())
+}
+
 // Errorf formats according to a format specifier and returns the string
 // as a value that satisfies error.
 // Errorf also records the stack trace at the point it was called.
diff --git a/errors_test.go b/errors_test.go
index 2089b2f7..7da40e2a 100644
--- a/errors_test.go
+++ b/errors_test.go
@@ -27,6 +27,26 @@ func TestNew(t *testing.T) {
 	}
 }
 
+func TestExistStack(t *testing.T) {
+	tests := []struct {
+		err  error
+		want bool
+	}{
+		{io.EOF, false},
+		{New("read error"), true},
+		{Wrap(io.EOF, "read error"), true},
+		{WithMessage(io.EOF, "read error"), false},
+		{WithStack(io.EOF), true},
+	}
+
+	for _, tt := range tests {
+		got := ExistStack(tt.err)
+		if got != tt.want {
+			t.Errorf("ExistStack(%v): got: %v, want %v", tt.err, got, tt.want)
+		}
+	}
+}
+
 func TestWrapNil(t *testing.T) {
 	got := Wrap(nil, "no error")
 	if got != nil {