Throw error if match isn't found but test.result has >0 elements

regex/re_test.go

@@ -790,6 +790,13 @@ func TestFindSubmatch(t *testing.T) {
 				}
 			}
 			match, err := regComp.FindSubmatch(test.str)
+			if err != nil {
+				if len(test.result) != 0 {
+					t.Errorf("Wanted %v got no match\n", test.result[0])
+				}
+			} else if len(test.result) == 0 {
+				t.Errorf("Wanted no match got %v\n", match)
+			}
 			for i := range match {
 				if match[i].IsValid() {
 					if test.result[0][i] != match[i] {