From 00bf8495f70167a829261e45836eac83924f2c18 Mon Sep 17 00:00:00 2001
From: Sean Marciniak <smarciniak@splunk.com>
Date: Thu, 24 Oct 2024 09:34:51 +1030
Subject: [PATCH] Correcting AsResponseError method

---
 errors.go      | 29 +++++++++++++++++++++++------
 errors_test.go | 13 ++++++++++++-
 2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/errors.go b/errors.go
index 1ef98e0..435ca63 100644
--- a/errors.go
+++ b/errors.go
@@ -38,12 +38,29 @@ func newResponseError(resp *http.Response, target int, targets ...int) error {
 	}
 }
 
-// IsResponseError is convenience function to see
-// if it can convert into RequestError.
-func IsResponseError(err error) (*ResponseError, bool) {
-	var re *ResponseError
-	if errors.As(err, &re) {
-		return err.(*ResponseError), true
+// AsResponseError is a convenience function to check the error
+// to see if it contains an `ResponseError` and returns the value with true.
+// If the error was initially joined using [errors.Join], it will check each error
+// within the list and return the first matching error.
+func AsResponseError(err error) (*ResponseError, bool) {
+	// When `errors.Join` is called, it returns an error that
+	// matches the provided interface.
+	if joined, ok := err.(interface{ Unwrap() []error }); ok {
+		for _, err := range joined.Unwrap() {
+			if re, ok := AsResponseError(err); ok {
+				return re, ok
+			}
+		}
+		return nil, false
+	}
+
+	for err != nil {
+		if re, ok := err.(*ResponseError); ok {
+			return re, true
+		}
+		// In case the error is wrapped using `fmt.Errorf`
+		// this will also account for that.
+		err = errors.Unwrap(err)
 	}
 	return nil, false
 }
diff --git a/errors_test.go b/errors_test.go
index ff3cc01..0ed14de 100644
--- a/errors_test.go
+++ b/errors_test.go
@@ -2,6 +2,7 @@ package signalfx
 
 import (
 	"errors"
+	"fmt"
 	"io"
 	"net/http"
 	"net/url"
@@ -130,12 +131,22 @@ func TestIsRequestError(t *testing.T) {
 			err:      &ResponseError{},
 			expected: true,
 		},
+		{
+			name:     "joined errors",
+			err:      errors.Join(errors.New("boom"), &ResponseError{}),
+			expected: true,
+		},
+		{
+			name:     "fmt error",
+			err:      fmt.Errorf("check permissions: %w", &ResponseError{}),
+			expected: true,
+		},
 	} {
 		tc := tc
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
 
-			_, ok := IsResponseError(tc.err)
+			_, ok := AsResponseError(tc.err)
 			assert.Equal(t, tc.expected, ok, "Must match the expected value")
 		})
 	}