improve tests

pkg/analyzer/testdata/src/opposite-chan-map-only/positive.go

@@ -38,3 +38,15 @@ func anyType() (any, error) {
 func m1() (map[int]int, error) {
 	return make(map[int]int), io.EOF // want "return both a non-nil error and a valid value: use separate returns instead"
 }
+
+func structPtrInvalid() (*int, error) {
+	return nil, nil
+}
+
+func structPtrValid() (*int, error) {
+	return new(int), nil
+}
+
+func chInvalid() (chan int, error) {
+	return nil, nil // want "return both a `nil` error and an invalid value: use a sentinel error instead"
+}

pkg/analyzer/testdata/src/opposite/opposite.go

@@ -71,3 +71,11 @@ type (
 )
 
 func wrap(err error) error { return err }
+
+func structPtr() (*int, error) {
+	return nil, nil // want "return both a `nil` error and an invalid value: use a sentinel error instead"
+}
+
+func structPtrValid() (*int, error) {
+	return new(int), nil
+}