2 files changed, 14 insertions, 0 deletions
diff --git a/core/fxcrt/bytestring_unittest.cpp b/core/fxcrt/bytestring_unittest.cpp
index 7095a1b799..abc3648f18 100644
--- a/core/fxcrt/bytestring_unittest.cpp
+++ b/core/fxcrt/bytestring_unittest.cpp
@@ -390,6 +390,13 @@ TEST(ByteString, OperatorNE) {
   EXPECT_TRUE(c_string3 != byte_string);
 }
 
+TEST(ByteString, OperatorPlus) {
+  EXPECT_EQ("I like dogs", "I like " + ByteString("dogs"));
+  EXPECT_EQ("Dogs like me", ByteString("Dogs") + " like me");
+  EXPECT_EQ("Oh no, error number 42",
+            "Oh no, error number " + ByteString::Format("%d", 42));
+}
+
 TEST(ByteString, Concat) {
   ByteString fred;
   fred.Concat("FRED", 4);
diff --git a/core/fxcrt/widestring_unittest.cpp b/core/fxcrt/widestring_unittest.cpp
index 37d4ecd581..9017fe0c54 100644
--- a/core/fxcrt/widestring_unittest.cpp
+++ b/core/fxcrt/widestring_unittest.cpp
@@ -395,6 +395,13 @@ TEST(WideString, OperatorNE) {
   EXPECT_TRUE(c_string3 != wide_string);
 }
 
+TEST(WideString, OperatorPlus) {
+  EXPECT_EQ(L"I like dogs", L"I like " + WideString(L"dogs"));
+  EXPECT_EQ(L"Dogs like me", WideString(L"Dogs") + L" like me");
+  EXPECT_EQ(L"Oh no, error number 42",
+            L"Oh no, error number " + WideString::Format(L"%d", 42));
+}
+
 TEST(WideString, ConcatInPlace) {
   WideString fred;
   fred.Concat(L"FRED", 4);