
All the previous refactoring to make the assertion fast paths smaller and faster also allows us to implement the fast paths just with thread-local and atomic variables, without full mutexes. However, the performance overhead of thread-safe assertions is still significant for single threaded usage: | slowdown | Debug | Release | |-----------|--------:|--------:| | fast path | 1.04x | 1.43x | | slow path | 1.16x | 1.22x | Thus, we don't make the assertions thread-safe by default, and instead provide a build-time configuration option that the users can set to get thread-safe assertions. This commit is functional, but it still needs some follow-up work: * We do not need full seq_cst increments for the atomic counters, and using weaker ones can be faster. * We brute-force updating the reporter-friendly totals from internal atomic counters by doing it everywhere. We should properly trace where this is needed instead. * Message macros (`INFO`, `UNSCOPED_INFO`, `CAPTURE`, etc) are not made thread safe in this commit, but they can be made thread safe in the future, by building on top of this work. * Add more tests, including with thread-sanitizer, and compiled examples to the repository. Right now, these changes have been compiled with tsan manually, but these tests are not added to CI. Closes #2948
What is Catch2?
Catch2 is mainly a unit testing framework for C++, but it also provides basic micro-benchmarking features, and simple BDD macros.
Catch2's main advantage is that using it is both simple and natural. Test names do not have to be valid identifiers, assertions look like normal C++ boolean expressions, and sections provide a nice and local way to share set-up and tear-down code in tests.
Example unit test
#include <catch2/catch_test_macros.hpp>
#include <cstdint>
uint32_t factorial( uint32_t number ) {
return number <= 1 ? number : factorial(number-1) * number;
}
TEST_CASE( "Factorials are computed", "[factorial]" ) {
REQUIRE( factorial( 1) == 1 );
REQUIRE( factorial( 2) == 2 );
REQUIRE( factorial( 3) == 6 );
REQUIRE( factorial(10) == 3'628'800 );
}
Example microbenchmark
#include <catch2/catch_test_macros.hpp>
#include <catch2/benchmark/catch_benchmark.hpp>
#include <cstdint>
uint64_t fibonacci(uint64_t number) {
return number < 2 ? number : fibonacci(number - 1) + fibonacci(number - 2);
}
TEST_CASE("Benchmark Fibonacci", "[!benchmark]") {
REQUIRE(fibonacci(5) == 5);
REQUIRE(fibonacci(20) == 6'765);
BENCHMARK("fibonacci 20") {
return fibonacci(20);
};
REQUIRE(fibonacci(25) == 75'025);
BENCHMARK("fibonacci 25") {
return fibonacci(25);
};
}
Note that benchmarks are not run by default, so you need to run it explicitly
with the [!benchmark]
tag.
Catch2 v3 has been released!
You are on the devel
branch, where the v3 version is being developed.
v3 brings a bunch of significant changes, the big one being that Catch2
is no longer a single-header library. Catch2 now behaves as a normal
library, with multiple headers and separately compiled implementation.
The documentation is slowly being updated to take these changes into account, but this work is currently still ongoing.
For migrating from the v2 releases to v3, you should look at our documentation. It provides a simple guidelines on getting started, and collects most common migration problems.
For the previous major version of Catch2 look into the v2.x
branch
here on GitHub.
How to use it
This documentation comprises these three parts:
- Why do we need yet another C++ Test Framework?
- Tutorial - getting started
- Reference section - all the details
More
- Issues and bugs can be raised on the Issue tracker on GitHub
- For discussion or questions please use our Discord
- See who else is using Catch2 in Open Source Software or commercially.