From 9e778b539c1d79c03223c4e07b9ac92b41dc1a74 Mon Sep 17 00:00:00 2001
From: Wesley Spikes <wesley.spikes@gmail.com>
Date: Tue, 25 Feb 2025 12:04:52 -0800
Subject: [PATCH] test: ErrorIs target and err both nil should pass

Go's builtin errors.Is returns true when both target and err are nil.
---
 internal/assertions/assertions.go | 2 +-
 must/must_test.go                 | 4 ++++
 test_test.go                      | 4 ++++
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/internal/assertions/assertions.go b/internal/assertions/assertions.go
index 585790e..d6254e1 100644
--- a/internal/assertions/assertions.go
+++ b/internal/assertions/assertions.go
@@ -164,7 +164,7 @@ func EqError(err error, msg string) (s string) {
 }
 
 func ErrorIs(err error, target error) (s string) {
-	if err == nil {
+	if err == nil && target != nil {
 		s = "expected non-nil error; got nil\n"
 		return
 	}
diff --git a/must/must_test.go b/must/must_test.go
index c3e7b49..2acf11f 100644
--- a/must/must_test.go
+++ b/must/must_test.go
@@ -165,6 +165,10 @@ func TestErrorIs_nil(t *testing.T) {
 	ErrorIs(tc, nil, err)
 }
 
+func TestErrorIs_nil_nil(t *testing.T) {
+	ErrorIs(t, nil, nil)
+}
+
 type FakeError string
 
 func (e FakeError) Error() string {
diff --git a/test_test.go b/test_test.go
index db6d857..2d12fd0 100644
--- a/test_test.go
+++ b/test_test.go
@@ -163,6 +163,10 @@ func TestErrorIs_nil(t *testing.T) {
 	ErrorIs(tc, nil, err)
 }
 
+func TestErrorIs_nil_nil(t *testing.T) {
+	ErrorIs(t, nil, nil)
+}
+
 type FakeError string
 
 func (e FakeError) Error() string {