assert: improve string literal representation in ErrEqual output

2 files changed, 10 insertions, 4 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3ffd5ea..4150b9e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,12 @@ SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
 SPDX-License-Identifier: Apache-2.0
 -->
 
+# v1.14.1 (TBD)
+
+Changes:
+
+- Improve presentation of string literals in `assert.ErrEqual()` output (same as for `assert.Equal()` in v1.11.0).
+
 # v1.14.0 (2026-08-18)
 
 Changes:
diff --git a/assert/errequal.go b/assert/errequal.go
index a297ead..df94e84 100644
--- a/assert/errequal.go
+++ b/assert/errequal.go
@@ -84,15 +84,15 @@ func errEqual(t TestingTB, actual error, expected any) error {
 		} else if errors.Is(actual, expected) {
 			return nil
 		} else {
-			return fmt.Errorf("expected %s, but got %q", formatErrorMessage(expected), actual.Error())
+			return fmt.Errorf("expected %s, but got %s", formatErrorMessage(expected), formatString(actual.Error()))
 		}
 	case string:
 		if actual == nil {
-			return fmt.Errorf("expected %q, but got no error", expected)
+			return fmt.Errorf("expected %s, but got no error", formatString(expected))
 		} else if actual.Error() == expected {
 			return nil
 		} else {
-			return fmt.Errorf("expected %q, but got %s", expected, formatErrorMessage(actual))
+			return fmt.Errorf("expected %s, but got %s", formatString(expected), formatErrorMessage(actual))
 		}
 	case *regexp.Regexp:
 		if actual == nil {
@@ -111,6 +111,6 @@ func formatErrorMessage(err error) string {
 	if _, ok := err.(missingError); ok { //nolint:errorlint // this error is never wrapped, so errors.Is() is unnecessary
 		return err.Error()
 	} else {
-		return fmt.Sprintf("%q", err.Error())
+		return formatString(err.Error())
 	}
 }