Gtest SEH Exception

[SimonEbner]

Running the following test using GTest causes an SEH Exception for me using VS 2017 / gcc 5.4

TEST(foo, fail1)
{
    auto obj = json{ {"foo", "bar"} };
    ASSERT_THAT(obj, Eq(obj));
}

MATCHER(IsFooObject, "")
{
    return arg == json{ { "foo", "bar" } };
}

TEST(foo, fail2)
{
    auto obj = json{ { "foo", "bar" } };
    ASSERT_THAT(obj, IsFooObject());
}

These 'simpler' tests, however, work fine.

TEST(foo, success1)
{
    auto obj = json{ { "foo", "bar" } };
    ASSERT_EQ(obj, obj);
}

TEST(foo, success2)
{
    auto obj = json{ { "foo", "bar" } };
    ASSERT_TRUE(obj == obj);
}

I could not find any information on how to make json.hpp together with Gtest work. Is there a chance to make custom matchers (MATCHER_P) work?

[nlohmann]

Thanks for reporting. I have no experience with Gtest. Can you post the exact exception/error message, and maybe a complete example program so I can try to reproduce/debug?

[SimonEbner]

Certainly. So I use the latest version (commit c38baf9858311e2887623465c8be433cfa585d2a) of gtest / gmock from https://github.com/google/googletest. The complete mail file is as follows

#include <gtest/gtest.h>
#include <gmock/gmock.h>
#include "json.hpp"

using namespace testing;
using namespace nlohmann;

TEST(foo, fail1)
{
      auto obj = json{ {"foo", "bar"} };
      ASSERT_THAT(obj, Eq(obj));
}

MATCHER(IsFooObject, "")
{
      return arg == json{ { "foo", "bar" } };
}

TEST(foo, fail2)
{
      auto obj = json{ { "foo", "bar" } };
      ASSERT_THAT(obj, IsFooObject());
}

TEST(foo, success1)
{
      auto obj = json{ { "foo", "bar" } };
      ASSERT_EQ(obj, obj);
}

TEST(foo, success2)
{
      auto obj = json{ { "foo", "bar" } };
      ASSERT_TRUE(obj == obj);
}

int main(int argc, char** argv)
{
      InitGoogleTest(&argc, argv);
      return RUN_ALL_TESTS();
}

which I compile using g++ json_test.cc --std=c++11 -lgtest -lgmock -lpthread -g. I can run the successful tests using ./a.out --gtest_filter="*success*" whereas the other tests fail with ./a.out --gtest_filter=*fail1* (or 2 respectively). When I run the test with gdb I get

Starting program: .../a.out 
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[==========] Running 4 tests from 1 test case.
[----------] Global test environment set-up.
[----------] 4 tests from foo
[ RUN      ] foo.fail1

Program received signal SIGSEGV, Segmentation fault.
0x00007ffff7946d22 in std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) ()
   from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
(gdb) where
#0  0x00007ffff7946d22 in std::basic_ostream<char, std::char_traits<char> >& std::__ostream_insert<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*, long) ()
   from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#1  0x00007ffff7947168 in std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char) () from /usr/lib/x86_64-linux-gnu/libstdc++.so.6
#2  0x00000000004100d6 in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:381
#3  0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#4  0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#5  0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#6  0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#7  0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#8  0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#9  0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#10 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#11 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#12 0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#13 0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#14 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#15 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#16 0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#17 0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#18 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#19 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#20 0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#21 0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#22 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#23 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#24 0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#25 0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#26 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#27 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#28 0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#29 0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869
#30 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#31 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, bool, long, unsigned long, double, std::allocator, nlo
---Type <return> to continue, or q <return> to quit---

The list goes on forever, so I'm not sure how much of that information is helpful in this issue. Please let me know if you require further information.

[theodelrieu]

We had this issue at work a long time ago (happened with boost::filesystem::path too), this is linked to this GTest issue.

We added this in a TestHelpers.hpp that we include on each test file to avoid breaking ODR.

namespace nlohmann
{
inline void PrintTo(json const& json, std::ostream* os)
{
  *os << json.dump();
}
}

[gregmarr]

Looks like a stack overflow due to infinite recursion. It's these 4 functions repeating over and over.

#10 0x000000000041017c in testing::internal::DefaultPrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (container=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:395
#11 0x000000000040f89d in testing::internal::PrintTo<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:479
#12 0x000000000040ea11 in testing::internal::UniversalPrinter<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> >::Print (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:720
#13 0x000000000040c890 in testing::internal::UniversalPrint<nlohmann::basic_json<std::map, std::vector, std::__cxx11::basic_string<char, std::char_traits, std::allocator >, bool, long, unsigned long, double, std::allocator, nlohmann::adl_serializer> > (value=..., os=0x7fffffffd4a0) at /usr/local/include/gtest/gtest-printers.h:869

[gregmarr]

Yes, I agree @theodelrieu , and here's a PR to googletest that purports to fix the issue. google/googletest#1186

[gregmarr]

@SimonEbner If you could try out that PR version and report in that PR that it fixes your issue, then that might help the PR get approved.

[SimonEbner]

awesome, thank you @theodelrieu for the local fix and @gregmarr for pointint out the PR, both solutions work for me.

[pboettch]

I just stumbled upon the same problem simply doing:

nlohmann::json j;
j = 1;
EXPECT_EQ(j, 0);

GoogleTest has (had?) problems printing j in case of test-failure.