Evaluate message argument passed to EXPECT_THROW_MSG once.

test/gtest-extra-test.cc

@@ -77,12 +77,18 @@ bool IsClosedInternal(int fd) {
 class SingleEvaluationTest : public ::testing::Test {
  protected:
   SingleEvaluationTest() {
+    p_ = s_;
     a_ = 0;
   }
-  
+
+  static const char* const s_;
+  static const char* p_;
+
   static int a_;
 };
 
+const char* const SingleEvaluationTest::s_ = "01234";
+const char* SingleEvaluationTest::p_;
 int SingleEvaluationTest::a_;
 
 void ThrowNothing() {}
@@ -91,6 +97,14 @@ void ThrowException() {
   throw std::runtime_error("test");
 }
 
+// Tests that when EXPECT_THROW_MSG fails, it evaluates its message argument
+// exactly once.
+TEST_F(SingleEvaluationTest, FailedASSERT_THROW_MSG) {
+  EXPECT_NONFATAL_FAILURE(
+      EXPECT_THROW_MSG(ThrowException(), std::exception, p_++), "01234");
+  EXPECT_EQ(s_ + 1, p_);
+}
+
 // Tests that assertion arguments are evaluated exactly once.
 TEST_F(SingleEvaluationTest, ExceptionTests) {
   // successful EXPECT_THROW_MSG

test/gtest-extra.h

@@ -44,15 +44,16 @@
 #define FMT_TEST_THROW_(statement, expected_exception, expected_message, fail) \
   GTEST_AMBIGUOUS_ELSE_BLOCKER_ \
   if (::testing::AssertionResult gtest_ar = ::testing::AssertionSuccess()) { \
+    std::string expected_message_str = expected_message; \
     bool gtest_caught_expected = false; \
     try { \
       GTEST_SUPPRESS_UNREACHABLE_CODE_WARNING_BELOW_(statement); \
     } \
     catch (expected_exception const& e) { \
-      if (expected_message != std::string(e.what())) { \
+      if (expected_message_str != e.what()) { \
         gtest_ar \
           << #statement " throws an exception with a different message.\n" \
-          << "Expected: " << expected_message << "\n" \
+          << "Expected: " << expected_message_str << "\n" \
           << "  Actual: " << e.what(); \
         goto GTEST_CONCAT_TOKEN_(gtest_label_testthrow_, __LINE__); \
       } \