catch2/docs/configuration.md

Compile-time configuration

Contents
main()/ implementation
Prefixing Catch macros
Terminal colour
Console width
stdout
Fallback stringifier
Default reporter
Other toggles
Windows header clutter
Enabling stringification

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

Catch does not use std::cout, std::cerr and std::clog directly but gets them from Catch::cout(), Catch::cerr() and Catch::clog respectively. If the above identifier is defined these functions are left unimplemented and you must implement them yourself. Their signatures are:

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

This can be useful on certain platforms that do not provide the standard iostreams, such as certain embedded systems.

Fallback stringifier

By default Catch's stringification machinery falls back to a "{?}". To let projects reuse their own existing stringification machinery, this fallback can be overridden by defining CATCH_CONFIG_FALLBACK_STRINGIFIER to a name of a function that should perform the stringification instead.

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++17 toggles

CATCH_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS  // Use std::uncaught_exceptions instead of std::uncaught_exception

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_DISABLE_MATCHERS           // Do not compile Matchers in this compilation unit
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

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

Defining this flag speeds up compilation of test files by ~20%, by making 2 changes:

• The -b (--break) flag no longer makes Catch break into debugger in the same stack frame as the failed test, but rather in a stack frame below.
• Non-exception family of macros ({REQUIRE,CHECK}{_,_FALSE, _THAT}, no longer use local try-catch block. This disables exception translation, 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, or the behaviour of setting -b flag and throwing unexpected exceptions will be unpredictable.

CATCH_CONFIG_DISABLE_MATCHERS

When CATCH_CONFIG_DISABLE_MATCHERS is defined, all mentions of Catch's Matchers are ifdef-ed away from the translation unit. Doing so will speed up compilation of that TU.

Note: If you define CATCH_CONFIG_DISABLE_MATCHERS in the same file as Catch's main is implemented, your test executable will fail to link if you use Matchers anywhere.

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_CHRONO_STRINGMAKER  // Provide StringMaker specialization for std::chrono::duration, std::chrono::timepoint
CATCH_CONFIG_ENABLE_ALL_STRINGMAKERS    // Defines all of the above

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