The main() entry point

The usual way of writing tests in C++ has always been into separate source files from the code they test that form an executable containing only tests. In that scenario the default main() provided by doctest is usually sufficient:

#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

This should be done in exactly one source file and is even a good idea to do this in a separate file with nothing else in it.

However if you need more control - want to set options with code to the execution context or want to integrate the framework in your production code - then the default main() just won't do the job. In that case use DOCTEST_CONFIG_IMPLEMENT.

All the command line options can be set like this (flags cannot because it wouldn't make sense). Filters can only be appended - the user cannot remove a filter given from the command line with code.

#define DOCTEST_CONFIG_IMPLEMENT
#include "doctest.h"

int main(int argc, char** argv) {
    doctest::Context context; // initialize

    // defaults
    context.addFilter("test-case-exclude", "*math*"); // exclude test cases with "math" in their name
    context.setOption("abort-after", 5);              // stop test execution after 5 failed assertions
    context.setOption("sort", "name");                // sort the test cases by their name

    context.applyCommandLine(argc, argv);

    // overrides
    context.setOption("no-breaks", true);             // don't break in the debugger when assertions fail

    int res = context.run(); // run

    if(context.shouldExit()) // important - query flags (and --exit) rely on the user doing this
        return res;          // propagate the result of the tests
    
    int client_stuff_return_code = 0;
    // your program - if the testing framework is integrated in your production code
    
    return res + client_stuff_return_code;
}

Note the call to .shouldExit() on the context - that is very important - it will be set when a query flag has been used (or the --no-run option is set to true) and it is the user's responsibility to exit the application in a normal way.

Dealing with shared objects (DLLs)

When integrating the framework in production code which gets built as a shared object (dll) everything still works. Many shared objects and an executable can have tests in them and can even use different versions of the doctest framework.

Check out this example which showcases how to call the tests in a shared object from the executable (and it also showcases that if a file with a test case is included both in the shared object and the executable then the test is registered in both places).

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