Progmasoft Catch3

An independently maintained C++ test framework: Catch3 keeps the practical, expressive test-writing model that developers expect, while adding a separately owned C++20 library for property checks, snapshots, structured results, and XML serialization.

Catch3 is not an official Catch2 release and is not endorsed by Catch2's maintainers. Its current compatibility engine is based on Catch2 3.16.0; upstream-originated files keep their upstream license. Progmasoft-authored additions have their own licensing terms. See the project scope and compatibility notes.

What Catch3 provides

• Familiar test authoring and execution. The existing test runner, assertions, sections, reporters, benchmarks, and command-line behavior remain available through the Catch2 compatibility surface.
• Deterministic property testing. Generate values from a reproducible seed, check a predicate over multiple trials, and shrink a failing input to a smaller counterexample.
• Text snapshots. Compare generated output against explicitly located snapshot files, with opt-in creation or replacement modes.
• Structured results and XML output. Build a runner-neutral result model and serialize it as deterministic JUnit-style XML.
• A compiled library, not a header-only package. Snapshot I/O and result/XML serialization are compiled C++20 implementations; templates and assertion macros remain in headers where needed.

Catch3 is in an early development stage. The Catch2-compatible runner is still its execution engine; Catch3 does not yet provide an independent runner. The property API currently checks one generated value per property and uses bounded, deterministic greedy shrinking. See current capabilities and limitations before adopting it in a production project.

Property-test example

#include <Progmasoft/Catch3.hpp>

TEST_CASE("generated integers stay within their requested domain", "[property]") {
    CATCH3_CHECK_PROPERTY(
        Progmasoft::Catch3::Integer<int>(1, 100),
        [](int value) { return value > 0; },
        Progmasoft::Catch3::PropertyOptions{
            .Trials = 250,
            .Seed = 0xC0FFEE,
            .MaxShrinkSteps = 200});
}

The root seed and trial-index derivation are stable, so a reported failing trial can be replayed. Generators can provide their own generation and shrinking behavior. See the property-testing guide for the API, seed guarantees, and shrinking contract.

Build and test

Bazel is the primary build and validation path. From the repository root:

bazel test //tests/Progmasoft:property_tests

The same suite is also available through the maintained CMake, Meson, Xmake, and Premake project files. Their setup details and toolchain requirements are in the build guide.

For a CMake consumer of the installed libraries:

find_package(Catch2 3.16 CONFIG REQUIRED)
find_package(ProgmasoftCatch3 3.16 CONFIG REQUIRED)

target_link_libraries(MyTests PRIVATE
    Progmasoft::Catch3
    Catch2::Catch2WithMain)

The Catch2 target supplies the compatibility runner and main; link Progmasoft::Catch3 for the compiled Catch3 additions. The two targets retain their separate language baselines and licensing boundaries.

Documentation

• Catch3 additions: properties, snapshots, results, and XML
• Project scope, compatibility policy, and limitations
• Catch2-compatible runner tutorial
• Catch2-compatible API reference
• Catch2 upstream project and source history

Issues and feature requests for Progmasoft Catch3 belong in the Progmasoft/Catch3 issue tracker.