Catch v3.0.0-preview2 Release Notes

Release Date: 2020-05-14 // over 1 year ago
  • Catch2 now uses statically compiled library as its distribution model.
    ✅ This also means that to get all of Catch2's functionality in a test file,
    you have to include multiple headers.

    For quick'n'dirty migration, you can replace the old #include <catch2/catch.hpp>
    with #include <catch2/catch_all.hpp>. This is a (one of) convenience
    header(s) that brings in all of headers in Catch2. By doing this,
    you should be able to migrate instantly, but at the cost of (significantly)
    increased compilation times. You should prefer piecemeal including
    ✅ headers that are actually required by your test code.

    ✅ The basic set of functionality (TEST_CASE, SECTION, REQUIRE) is in
    catch2/catch_test_macros.hpp. Matchers are in matchers subfolder,
    generators in generators subfolder, and so on.

    📚 Note that documentation has not yet been updated to account for the
    🆕 new design.

    🙋 FAQ

    • Why is Catch2 moving to separate headers?
      • The short answer is future extensibility and scalability. The long answer is complex and can be found on my blog, but at the most basic level, it is that providing single-header distribution is at odds with providing variety of useful features. When Catch2 was distributed in a single header, adding a new Matcher would cause overhead for everyone, but was useful only to a subset of users. This meant that the barrier to entry for new Matchers/Generators/etc is high in single header model, but much smaller in the new model.
    • Will Catch2 again distribute single-header version in the future?
      • No. But I intend to provide sqlite-style distribution option, with 1 header and 1 "unity" .cpp file. Do note that the header will have similar problem to the catch_all.hpp header.
    • Why the big breaking change caused by replacing catch.hpp with catch_all.hpp?
      • The convenience header catch_all.hpp exists for two reasons. One of them is to provide a way for quick migration from Catch2, the second one is to provide a simple way to test things with Catch2. Using it for migration has one drawback in that it is big. This means that including it will cause significant compile time drag, and so using it to migrate should be a concious decision by the user, not something they can just stumble into unknowingly.
    • Why does CMake/pkg-config/etc report version 3.0.0?
      • Lot of tooling does not handle preview versions too well, so we have to use proper new major version. The final release will use version 3.0.1 to avoid conflicts with these preview versions.

    (Potentially) Breaking changes

    • Catch2 now uses statically compiled library as its distribution model
      • Including catch.hpp no longer works
    • ANON_TEST_CASE has been removed, use TEST_CASE with no arguments instead (#1220)
    • --list* commands no longer have non-zero return code (#1410)
    • 🚚 --list-test-names-only has been removed (#1190)
      • You should use verbosity-modifiers for --list-tests instead
    • --list* commands are now piped through the reporters
      • The top-level reporter interface provides default implementation that works just as the old one
      • XmlReporter outputs a machine-parseable XML
    • 🚚 TEST_CASE description support has been removed
      • If the second argument has text outside tags, the text will be ignored.
    • ✅ Hidden test cases are no longer included just because they don't match an exclusion tag
      • Previously, a TEST_CASE("A", "[.foo]") would be included by asking for ~[bar].
    • PredicateMatcher is no longer type erased.
      • This means that the type of the provided predicate is part of the PredicateMatcher's type
    • SectionInfo no longer contains section description as a member (#1319)
      • You can still write SECTION("ShortName", "Long and wordy description"), but the description is thrown away
      • The description type now must be a const char* or be implicitly convertible to it
    • 🚚 The [!hide] tag has been removed.
      • Use [.] or [.foo] instead.
    • Lvalues of composed matchers cannot be composed further
    • ✅ Uses of REGISTER_TEST_CASE macro need to be followed by a semicolon
      • This does not change TEST_CASE and friends in any way
    • 🚚 IStreamingReporter::IsMulti member function was removed
      • This is very unlikely to actually affect anyone, as it was default-implemented in the interface, and only used internally
    • Various classes not designed for user-extension have been made final
      • ListeningReporter is now final
      • Concrete Matchers (e.g. UnorderedEquals vector matcher) are now final
      • All Generators are now final
    • Matcher namespacing has been redone
      • Matcher types are no longer in deeply nested namespaces
      • Matcher factory functions are no longer brought into Catch namespace
      • This means that all public-facing matcher-related functionality is now in Catch::Matchers namespace
    • Defining CATCH_CONFIG_MAIN will no longer create main in that TU.
      • Link with libCatch2Main.a, or the proper CMake/pkg-config target
      • If you want to write custom main, include catch2/catch_session.hpp
      • You should instead include the appropriate headers as needed.
    • CATCH_CONFIG_IMPL has been removed.
      • The implementation is now compiled into a static library.

    👌 Improvements

    • Matchers have been extended with the ability to use different signatures of match (#1307, #1553, #1554, #1843)
      • This includes having templated match member function
      • See the rewritten Matchers documentation for details
      • Catch2 currently provides some generic matchers, but there should be more before final release of v3
      • So far, IsEmpty, SizeIs, and Contains are provided.
      • At least ElementsAre and UnorderedElementsAre are planned.

    🛠 Fixes

    • The INFO macro no longer contains superfluous semicolon (#1456)
    • 💻 The --list* family of command line flags now return 0 on success (#1410, #1146)

    Other changes

    • CATCH_CONFIG_DISABLE_MATCHERS no longer exists.
      • If you do not want to use Matchers in a TU, do not include their header.
      • StringMaker specializations for are always provided
    • Catch2's CMake now provides 2 targets, Catch2 and Catch2WithMain.
      • Catch2 is the statically compiled implementation by itself
      • Catch2WithMain also links in the default main
    • 📦 Catch2's pkg-config integration also provides 2 packages
      • catch2 is the statically compiled implementation by itself
      • catch2-with-main also links in the default main