test: ErrorIs target and err both nil should pass

SpikesDivZero · SpikesDivZero · commit 9e778b539c1d · 2025-02-25T12:04:52.000-08:00
Go's builtin errors.Is returns true when both target and err are nil.
diff --git 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
diff --git 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 {

Original file line number	Diff line number	Diff line change
`@@ -164,7 +164,7 @@ func EqError(err error, msg string) (s string) {`
`164`	`164`	`}`
`165`	`165`
`166`	`166`	`func ErrorIs(err error, target error) (s string) {`
`167`		`- if err == nil {`
	`167`	`+ if err == nil && target != nil {`
`168`	`168`	`s = "expected non-nil error; got nil\n"`
`169`	`169`	`return`
`170`	`170`	`}`
Original file line number	Diff line number	Diff line change
`@@ -163,6 +163,10 @@ func TestErrorIs_nil(t *testing.T) {`
`163`	`163`	`ErrorIs(tc, nil, err)`
`164`	`164`	`}`
`165`	`165`
	`166`	`+func TestErrorIs_nil_nil(t *testing.T) {`
	`167`	`+ ErrorIs(t, nil, nil)`
	`168`	`+}`
	`169`	`+`
`166`	`170`	`type FakeError string`
`167`	`171`
`168`	`172`	`func (e FakeError) Error() string {`