catch2/docs/configuration.md

Compile-time configuration

Contents
Prefixing Catch macros
Terminal colour
Console width
stdout
Fallback stringifier
Default reporter
Bazel support
C++11 toggles
C++17 toggles
Other toggles
Enabling stringification
Disabling exceptions
Overriding Catch's debug break (-b)
Static analysis support

Catch2 is designed to "just work" as much as possible, and most of the configuration options below are changed automatically during compilation, according to the detected environment. However, this detection can also be overridden by users, using macros documented below, and/or CMake options with the same name.

Prefixing Catch macros

CATCH_CONFIG_PREFIX_ALL       // Prefix all macros with CATCH_
CATCH_CONFIG_PREFIX_MESSAGES  // Prefix only INFO, UNSCOPED_INFO, WARN and CAPTURE

To keep test code clean and uncluttered Catch uses short macro names (e.g. TEST_CASE and REQUIRE). Occasionally these may conflict with identifiers from platform headers or the system under test. In this case the above identifier can be defined. This will cause all the Catch user macros to be prefixed with CATCH_ (e.g. CATCH_TEST_CASE and CATCH_REQUIRE).

Terminal colour

CATCH_CONFIG_COLOUR_WIN32     // Force enables compiling colouring impl based on Win32 console API
CATCH_CONFIG_NO_COLOUR_WIN32  // Force disables ...

Yes, Catch2 uses the british spelling of colour.

Catch2 attempts to autodetect whether the Win32 console colouring API, SetConsoleTextAttribute, is available, and if it is available it compiles in a console colouring implementation that uses it.

This option can be used to override Catch2's autodetection and force the compilation either ON or OFF.

Console width

CATCH_CONFIG_CONSOLE_WIDTH = x // where x is a number

Catch formats output intended for the console to fit within a fixed number of characters. This is especially important as indentation is used extensively and uncontrolled line wraps break this. By default a console width of 80 is assumed but this can be controlled by defining the above identifier to be a different value.

stdout

CATCH_CONFIG_NOSTDOUT

To support platforms that do not provide std::cout, std::cerr and std::clog, Catch does not use them directly, but rather calls Catch::cout, Catch::cerr and Catch::clog. You can replace their implementation by defining CATCH_CONFIG_NOSTDOUT and implementing them yourself, their signatures are:

std::ostream& cout();
std::ostream& cerr();
std::ostream& clog();

You can see an example of replacing these functions here.

Fallback stringifier

By default, when Catch's stringification machinery has to stringify a type that does not specialize StringMaker, does not overload operator<<, is not an enumeration and is not a range, it uses "{?}". This can be overridden by defining CATCH_CONFIG_FALLBACK_STRINGIFIER to name of a function that should perform the stringification instead.

All types that do not provide StringMaker specialization or operator<< overload will be sent to this function (this includes enums and ranges). The provided function must return std::string and must accept any type, e.g. via overloading.

Note that if the provided function does not handle a type and this type requires to be stringified, the compilation will fail.

Default reporter

Catch's default reporter can be changed by defining macro CATCH_CONFIG_DEFAULT_REPORTER to string literal naming the desired default reporter.

This means that defining CATCH_CONFIG_DEFAULT_REPORTER to "console" is equivalent with the out-of-the-box experience.

Bazel support

Compiling Catch2 with CATCH_CONFIG_BAZEL_SUPPORT force-enables Catch2's support for Bazel's environment variables (normally Catch2 looks for BAZEL_TEST=1 env var first).

This can be useful if you are using older versions of Bazel, that do not yet have BAZEL_TEST env var support.

CATCH_CONFIG_BAZEL_SUPPORT was introduced in Catch2 3.0.1.

CATCH_CONFIG_BAZEL_SUPPORT was deprecated in Catch2 3.1.0.

C++11 toggles

CATCH_CONFIG_CPP11_TO_STRING // Use `std::to_string`

Because we support platforms whose standard library does not contain std::to_string, it is possible to force Catch to use a workaround based on std::stringstream. On platforms other than Android, the default is to use std::to_string. On Android, the default is to use the stringstream workaround. As always, it is possible to override Catch's selection, by defining either CATCH_CONFIG_CPP11_TO_STRING or CATCH_CONFIG_NO_CPP11_TO_STRING.

C++17 toggles

CATCH_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS  // Override std::uncaught_exceptions (instead of std::uncaught_exception) support detection
CATCH_CONFIG_CPP17_STRING_VIEW          // Override std::string_view support detection (Catch provides a StringMaker specialization by default)
CATCH_CONFIG_CPP17_VARIANT              // Override std::variant support detection (checked by CATCH_CONFIG_ENABLE_VARIANT_STRINGMAKER)
CATCH_CONFIG_CPP17_OPTIONAL             // Override std::optional support detection (checked by CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER)
CATCH_CONFIG_CPP17_BYTE                 // Override std::byte support detection (Catch provides a StringMaker specialization by default)

CATCH_CONFIG_CPP17_STRING_VIEW was introduced in Catch2 2.4.1.

Catch contains basic compiler/standard detection and attempts to use some C++17 features whenever appropriate. This automatic detection can be manually overridden in both directions, that is, a feature can be enabled by defining the macro in the table above, and disabled by using _NO_ in the macro, e.g. CATCH_CONFIG_NO_CPP17_UNCAUGHT_EXCEPTIONS.

Other toggles

CATCH_CONFIG_COUNTER                    // Use __COUNTER__ to generate unique names for test cases
CATCH_CONFIG_WINDOWS_SEH                // Enable SEH handling on Windows
CATCH_CONFIG_FAST_COMPILE               // Sacrifices some (rather minor) features for compilation speed
CATCH_CONFIG_POSIX_SIGNALS              // Enable handling POSIX signals
CATCH_CONFIG_WINDOWS_CRTDBG             // Enable leak checking using Windows's CRT Debug Heap
CATCH_CONFIG_DISABLE_STRINGIFICATION    // Disable stringifying the original expression
CATCH_CONFIG_DISABLE                    // Disables assertions and test case registration
CATCH_CONFIG_WCHAR                      // Enables use of wchart_t
CATCH_CONFIG_EXPERIMENTAL_REDIRECT      // Enables the new (experimental) way of capturing stdout/stderr
CATCH_CONFIG_USE_ASYNC                  // Force parallel statistical processing of samples during benchmarking
CATCH_CONFIG_ANDROID_LOGWRITE           // Use android's logging system for debug output
CATCH_CONFIG_GLOBAL_NEXTAFTER           // Use nextafter{,f,l} instead of std::nextafter
CATCH_CONFIG_GETENV                     // System has a working `getenv`
CATCH_CONFIG_USE_BUILTIN_CONSTANT_P     // Use __builtin_constant_p to trigger warnings

CATCH_CONFIG_ANDROID_LOGWRITE and CATCH_CONFIG_GLOBAL_NEXTAFTER were introduced in Catch2 2.10.0

CATCH_CONFIG_GETENV was introduced in Catch2 3.2.0

CATCH_CONFIG_USE_BUILTIN_CONSTANT_P was introduced in Catch2 vX.Y.Z

Currently Catch enables CATCH_CONFIG_WINDOWS_SEH only when compiled with MSVC, because some versions of MinGW do not have the necessary Win32 API support.

CATCH_CONFIG_POSIX_SIGNALS is on by default, except when Catch is compiled under Cygwin, where it is disabled by default (but can be force-enabled by defining CATCH_CONFIG_POSIX_SIGNALS).

CATCH_CONFIG_GETENV is on by default, except when Catch2 is compiled for platforms that lacks working std::getenv (currently Windows UWP and Playstation).

CATCH_CONFIG_WINDOWS_CRTDBG is off by default. If enabled, Windows's CRT is used to check for memory leaks, and displays them after the tests finish running. This option only works when linking against the default main, and must be defined for the whole library build.

CATCH_CONFIG_WCHAR is on by default, but can be disabled. Currently it is only used in support for DJGPP cross-compiler.

With the exception of CATCH_CONFIG_EXPERIMENTAL_REDIRECT, these toggles can be disabled by using _NO_ form of the toggle, e.g. CATCH_CONFIG_NO_WINDOWS_SEH.

CATCH_CONFIG_USE_BUILTIN_CONSTANT_P is ON by default for Clang and GCC (but as far as possible, not for other compilers masquerading for these two). However, it can cause bugs where the enclosed code is evaluated, even though it should not be, e.g. in #2925.

CATCH_CONFIG_FAST_COMPILE

This compile-time flag speeds up compilation of assertion macros by ~20%, by disabling the generation of assertion-local try-catch blocks for non-exception family of assertion macros ({REQUIRE,CHECK}{``,_FALSE, _THAT}). This disables translation of exceptions thrown under these assertions, but should not lead to false negatives.

CATCH_CONFIG_FAST_COMPILE has to be either defined, or not defined, in all translation units that are linked into single test binary.

CATCH_CONFIG_DISABLE_STRINGIFICATION

This toggle enables a workaround for VS 2017 bug. For details see known limitations.

CATCH_CONFIG_DISABLE

This toggle removes most of Catch from given file. This means that TEST_CASEs are not registered and assertions are turned into no-ops. Useful for keeping tests within implementation files (ie for functions with internal linkage), instead of in external files.

This feature is considered experimental and might change at any point.

Inspired by Doctest's DOCTEST_CONFIG_DISABLE

Enabling stringification

By default, Catch does not stringify some types from the standard library. This is done to avoid dragging in various standard library headers by default. However, Catch does contain these and can be configured to provide them, using these macros:

CATCH_CONFIG_ENABLE_PAIR_STRINGMAKER     // Provide StringMaker specialization for std::pair
CATCH_CONFIG_ENABLE_TUPLE_STRINGMAKER    // Provide StringMaker specialization for std::tuple
CATCH_CONFIG_ENABLE_VARIANT_STRINGMAKER  // Provide StringMaker specialization for std::variant, std::monostate (on C++17)
CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER // Provide StringMaker specialization for std::optional (on C++17)
CATCH_CONFIG_ENABLE_ALL_STRINGMAKERS     // Defines all of the above

CATCH_CONFIG_ENABLE_VARIANT_STRINGMAKER was introduced in Catch2 2.4.1.

CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER was introduced in Catch2 2.6.0.

Disabling exceptions

Introduced in Catch2 2.4.0.

By default, Catch2 uses exceptions to signal errors and to abort tests when an assertion from the REQUIRE family of assertions fails. We also provide an experimental support for disabling exceptions. Catch2 should automatically detect when it is compiled with exceptions disabled, but it can be forced to compile without exceptions by defining

CATCH_CONFIG_DISABLE_EXCEPTIONS

Note that when using Catch2 without exceptions, there are 2 major limitations:

1. If there is an error that would normally be signalled by an exception, the exception's message will instead be written to Catch::cerr and std::terminate will be called.
2. If an assertion from the REQUIRE family of macros fails, std::terminate will be called after the active reporter returns.

There is also a customization point for the exact behaviour of what happens instead of exception being thrown. To use it, define

CATCH_CONFIG_DISABLE_EXCEPTIONS_CUSTOM_HANDLER

and provide a definition for this function:

namespace Catch {
    [[noreturn]]
    void throw_exception(std::exception const&);
}

Overriding Catch's debug break (-b)

Introduced in Catch2 2.11.2.

You can override Catch2's break-into-debugger code by defining the CATCH_BREAK_INTO_DEBUGGER() macro. This can be used if e.g. Catch2 does not know your platform, or your platform is misdetected.

The macro will be used as is, that is, CATCH_BREAK_INTO_DEBUGGER(); must compile and must break into debugger.

Static analysis support

Introduced in Catch2 3.4.0.

Some parts of Catch2, e.g. SECTIONs, can be hard for static analysis tools to reason about. Catch2 can change its internals to help static analysis tools reason about the tests.

Catch2 automatically detects some static analysis tools (initial implementation checks for clang-tidy and Coverity), but you can override its detection (in either direction) via

CATCH_CONFIG_EXPERIMENTAL_STATIC_ANALYSIS_SUPPORT     // force enables static analysis help
CATCH_CONFIG_NO_EXPERIMENTAL_STATIC_ANALYSIS_SUPPORT  // force disables static analysis help

As the name suggests, this is currently experimental, and thus we provide no backwards compatibility guarantees.

DO NOT ENABLE THIS FOR BUILDS YOU INTEND TO RUN. The changed internals are not meant to be runnable, only "scannable".

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