catch2/docs/configuration.md

Compile-time configuration

Contents
main()/ implementation
Reporter / Listener interfaces
Prefixing Catch macros
Terminal colour
Console width
stdout
Fallback stringifier
Default reporter
C++11 toggles
C++17 toggles
Other toggles
Windows header clutter
Enabling stringification
Disabling exceptions
Overriding Catch's debug break (-b)

Catch is designed to "just work" as much as possible. For most people the only configuration needed is telling Catch which source file should host all the implementation code (CATCH_CONFIG_MAIN).

Nonetheless there are still some occasions where finer control is needed. For these occasions Catch exposes a set of macros for configuring how it is built.

main()/ implementation

CATCH_CONFIG_MAIN      // Designates this as implementation file and defines main()
CATCH_CONFIG_RUNNER    // Designates this as implementation file

Although Catch is header only it still, internally, maintains a distinction between interface headers and headers that contain implementation. Only one source file in your test project should compile the implementation headers and this is controlled through the use of one of these macros - one of these identifiers should be defined before including Catch in exactly one implementation file in your project.

Reporter / Listener interfaces

CATCH_CONFIG_EXTERNAL_INTERFACES  // Brings in necessary headers for Reporter/Listener implementation

Brings in various parts of Catch that are required for user defined Reporters and Listeners. This means that new Reporters and Listeners can be defined in this file as well as in the main file.

Implied by both CATCH_CONFIG_MAIN and CATCH_CONFIG_RUNNER.

Prefixing Catch macros

CATCH_CONFIG_PREFIX_ALL

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_NONE      // completely disables all text colouring
CATCH_CONFIG_COLOUR_WINDOWS   // forces the Win32 console API to be used
CATCH_CONFIG_COLOUR_ANSI      // forces ANSI colour codes to be used

Yes, I am English, so I will continue to spell "colour" with a 'u'.

When sending output to the terminal, if it detects that it can, Catch will use colourised text. On Windows the Win32 API, SetConsoleTextAttribute, is used. On POSIX systems ANSI colour escape codes are inserted into the stream.

For finer control you can define one of the above identifiers (these are mutually exclusive - but that is not checked so may behave unexpectedly if you mix them):

Note that when ANSI colour codes are used "unistd.h" must be includable - along with a definition of isatty()

Typically you should place the #define before #including "catch.hpp" in your main source file - but if you prefer you can define it for your whole project by whatever your IDE or build system provides for you to do so.

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 usem the 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.

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  // Use std::uncaught_exceptions instead of std::uncaught_exception
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 Catch 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_ANDROID_LOGWRITE and CATCH_CONFIG_GLOBAL_NEXTAFTER were introduced in Catch 2.10.0

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_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.

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_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

Windows header clutter

On Windows Catch includes windows.h. To minimize global namespace clutter in the implementation file, it defines NOMINMAX and WIN32_LEAN_AND_MEAN before including it. You can control this behaviour via two macros:

CATCH_CONFIG_NO_NOMINMAX            // Stops Catch from using NOMINMAX macro 
CATCH_CONFIG_NO_WIN32_LEAN_AND_MEAN // Stops Catch from using WIN32_LEAN_AND_MEAN macro

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 Catch 2.4.1.

CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER was introduced in Catch 2.6.0.

Disabling exceptions

Introduced in Catch 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 Catch X.Y.Z.

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.

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