Throwing exception in a mocked method

[killkrt]

Description

I am mocking a method in order to raise an exception (using Trompeloeil) and I want to check if its caller protect itself catching the exception correctly.

Steps to reproduce

This is a very simplified version of my code:

struct Foo
{
    virtual void mayThrow() = 0;
    
    virtual bool throwerCaller()
    {
        bool res = false;
        try
        {
            mayThrow();
            res = true;
        }
        catch(...)
        {
            res = false;
        }
        return res;
    }
}

The test should check whether the method mayThrow throws an exception, its caller method (throwerCaller) returns false.

    struct MockedFoo : Foo
    {
         MAKE_MOCK0( mayThrow(), void() );
    };

    TEST_CASE("Foo")
    {
         MockedFoo foo;
         foo.REQUIRE_CALL( foo, mayThrow() ).THROW( std::exception() );
         CHECK_FALSE( foo.throwerCaller() );
         // Even using CHECK_THROWS_AS( foo.throwCaller(), const std::exception& ) works
    }

Running this code it will abort due to a crash:

FATAL ERROR: test case CRASHED: SIGABRT - Abort (abnormal termination) signal

Not sure that this is an issue of Doctest or Trompeloeil.

• doctest version: 2.3.3
• Operating System: macOS 10.14.6
• Compiler+version: clang-1001.0.46.4

[onqtam]

well this is printed by the doctest framework - it has intercepted a SIGABRT signal... You could try defining DOCTEST_CONFIG_NO_POSIX_SIGNALS before including doctest in the entire test binary - that will disable signal catching on UNIX and you'll get the original SIGABRT message - virtual functions could be the reason for SIGABRT - here is one example of how you could shoot yourself in the foot with virtual functions and constructors/destructors: https://rextester.com/JVBF97486

I don't know enough about Trompeloeil but I doubt that this issue is related to doctest.

[killkrt]

Thank you for the reply.

Anyway, that's strange, since my method throwerCaller is wrapping the call to mayThow with a try{} catch{}, so no exception should be propagated.

Uhm... Maybe it's a Trompeloeil issue?

[onqtam]

I don't know... Did you try defining DOCTEST_CONFIG_NO_POSIX_SIGNALS so doctest doesn't capture the signals on its own? Have you tried stepping through the code with a debugger to see on which line the crash happens? Or perhaps even printf-debugging - logging messages between the lines?

[killkrt]

I tried and now it's failing with another error:

The output from the failed tests:

1/1 automatictests                          FAIL     0.37 s (killed by signal 6 SIGABRT)

--- command ---
/.../build/tests/automatictests
--- stderr ---
terminate called after throwing an instance of 'std::exception'
  what():  std::exception
-------

I debugged the code and it crash as it calls mayThrow even if it is wrapped by a try-catch.
This is the real code:

        try
        {
            // Stop should not fail!
            stop(); //  <-- Crash here when this mocked method is throwing an exception
            state = CommunicationState::Stop;
        }
        catch ( const std::exception& exc )
        {
            // Logging error here, anyway this code is never executed
        }
        catch ( ... )
        {
            // Logging error here, anyway this code is never executed
        }

[onqtam]

I don't think this is related to doctest - you could try to separate this from the doctest stuff and try to reproduce it in a simple main() function. I also don't have experience with mocking frameworks - you could ask this in the issues section of Trompeloeil - and make sure to include the entire code and not separate snippets, so it's easier to understand. Sorry for not being able to help.

[killkrt]

@onqtam you have been very supportive and kind.

I've followed your hint and I tried to rewrite the test bypassing Trompeloeil (so implementing manually a mocked class) and it works as expected, so I guess that there is something that I'm missing in Trompeloeil.

Thank your patience and I'm sorry wasted your time.