Make exit codes available to users

[Laguna1989]

Description
Currently (catch2 v3.8.0) the exit codes are defined in an anonymous namespace inside catch_session.cpp. permalink to github code

namespace Catch {

    namespace {
        static constexpr int TestFailureExitCode = 42;
        static constexpr int UnspecifiedErrorExitCode = 1;
        static constexpr int AllTestsSkippedExitCode = 4;
        static constexpr int NoTestsRunExitCode = 2;
        static constexpr int UnmatchedTestSpecExitCode = 3;
        static constexpr int InvalidTestSpecExitCode = 5;
// more code
    }
}

When writing a user-defined main function that calls auto const result = Catch::Session().run(argc, argv), it would be helpful to be able compare the returned result to the defined values.
Currently this is not possible as they are only inside the anonymous namespace, leading to internal linkage. Redefining the exit values in user code is not optimal.

My suggestion would be to define the exit codes in the catch_session.hpp header, so they are available to end-users.

[Laguna1989]

Thanks for taking this into account ❤️

[ChrisThrasher]

You’re welcome! Let us know how you end up using this.

[Laguna1989]

I am working on a project that uses gtest, but we want to switch to catch2 for new test cases.
There are multiple test executables, some of which already have catch2 tests and some don't. Catch2 reports "no test cases" as an error. I still want that to pass as there are gtests. With those error codes publicly available I can just check for your error value instead (and silently accept it as a pass) of using my own hard coded one that might go out of sync with your internal value.

[horenmar]

Note that you can also configure the session not to error out on zero test cases.