docs/TestingLibcxx.rst - third_party/libcxx - Git at Google

 ==============
 Testing libc++
 ==============

 .. contents::
   :local:

 Getting Started
 ===============

 libc++ uses LIT to configure and run its tests.

 The primary way to run the libc++ tests is by using `make check-libcxx`.

 However since libc++ can be used in any number of possible
 configurations it is important to customize the way LIT builds and runs
 the tests. This guide provides information on how to use LIT directly to
 test libc++.

 Please see the `Lit Command Guide`_ for more information about LIT.

 .. _LIT Command Guide: http://llvm.org/docs/CommandGuide/lit.html

 Setting up the Environment
 --------------------------

 After building libc++ you must setup your environment to test libc++ using
 LIT.

 #. Create a shortcut to the actual lit executable so that you can invoke it
    easily from the command line.

    .. code-block:: bash

      $ alias lit='python path/to/llvm/utils/lit/lit.py'

 #. Tell LIT where to find your build configuration.

    .. code-block:: bash

      $ export LIBCXX_SITE_CONFIG=path/to/build-libcxx/test/lit.site.cfg

 Example Usage
 -------------

 Once you have your environment set up and you have built libc++ you can run
 parts of the libc++ test suite by simply running `lit` on a specified test or
 directory. For example:

 .. code-block:: bash

   $ cd path/to/src/libcxx
   $ lit -sv test/std/re # Run all of the std::regex tests
   $ lit -sv test/std/depr/depr.c.headers/stdlib_h.pass.cpp # Run a single test
   $ lit -sv test/std/atomics test/std/threads # Test std::thread and std::atomic

 Sometimes you'll want to change the way LIT is running the tests. Custom options
 can be specified using the `--param=<name>=<val>` flag. The most common option
 you'll want to change is the standard dialect (ie -std=c++XX). By default the
 test suite will select the newest C++ dialect supported by the compiler and use
 that. However if you want to manually specify the option like so:

 .. code-block:: bash

   $ lit -sv test/std/containers # Run the tests with the newest -std
   $ lit -sv --param=std=c++03 test/std/containers # Run the tests in C++03

 Occasionally you'll want to add extra compile or link flags when testing.
 You can do this as follows:

 .. code-block:: bash

   $ lit -sv --param=compile_flags='-Wcustom-warning'
   $ lit -sv --param=link_flags='-L/custom/library/path'

 Some other common examples include:

 .. code-block:: bash

   # Specify a custom compiler.
   $ lit -sv --param=cxx_under_test=/opt/bin/g++ test/std

   # Enable warnings in the test suite
   $ lit -sv --param=enable_warnings=true test/std

   # Use UBSAN when running the tests.
   $ lit -sv --param=use_sanitizer=Undefined


 LIT Options
 ===========

 :program:`lit` [*options*...] [*filenames*...]

 Command Line Options
 --------------------

 To use these options you pass them on the LIT command line as --param NAME or
 --param NAME=VALUE. Some options have default values specified during CMake's
 configuration. Passing the option on the command line will override the default.

 .. program:: lit

 .. option:: cxx_under_test=<path/to/compiler>

   Specify the compiler used to build the tests.

 .. option:: cxx_stdlib_under_test=<stdlib name>

   **Values**: libc++, libstdc++

   Specify the C++ standard library being tested. Unless otherwise specified
   libc++ is used. This option is intended to allow running the libc++ test
   suite against other standard library implementations.

 .. option:: std=<standard version>

   **Values**: c++98, c++03, c++11, c++14, c++17, c++2a

   Change the standard version used when building the tests.

 .. option:: libcxx_site_config=<path/to/lit.site.cfg>

   Specify the site configuration to use when running the tests.  This option
   overrides the environment variable LIBCXX_SITE_CONFIG.

 .. option:: cxx_headers=<path/to/headers>

   Specify the c++ standard library headers that are tested. By default the
   headers in the source tree are used.

 .. option:: cxx_library_root=<path/to/lib/>

   Specify the directory of the libc++ library to be tested. By default the
   library folder of the build directory is used. This option cannot be used
   when use_system_cxx_lib is provided.


 .. option:: cxx_runtime_root=<path/to/lib/>

   Specify the directory of the libc++ library to use at runtime. This directory
   is not added to the linkers search path. This can be used to compile tests
   against one version of libc++ and run them using another. The default value
   for this option is `cxx_library_root`.

 .. option:: use_system_cxx_lib=<bool>

   **Default**: False

   Enable or disable testing against the installed version of libc++ library.
   Note: This does not use the installed headers.

 .. option:: use_lit_shell=<bool>

   Enable or disable the use of LIT's internal shell in ShTests. If the
   environment variable LIT_USE_INTERNAL_SHELL is present then that is used as
   the default value. Otherwise the default value is True on Windows and False
   on every other platform.

 .. option:: compile_flags="<list-of-args>"

   Specify additional compile flags as a space delimited string.
   Note: This options should not be used to change the standard version used.

 .. option:: link_flags="<list-of-args>"

   Specify additional link flags as a space delimited string.

 .. option:: debug_level=<level>

   **Values**: 0, 1

   Enable the use of debug mode. Level 0 enables assertions and level 1 enables
   assertions and debugging of iterator misuse.

 .. option:: use_sanitizer=<sanitizer name>

   **Values**: Memory, MemoryWithOrigins, Address, Undefined

   Run the tests using the given sanitizer. If LLVM_USE_SANITIZER was given when
   building libc++ then that sanitizer will be used by default.

 .. option:: color_diagnostics

   Enable the use of colorized compile diagnostics. If the color_diagnostics
   option is specified or the environment variable LIBCXX_COLOR_DIAGNOSTICS is
   present then color diagnostics will be enabled.

 .. option:: llvm_unwinder

   Enable the use of LLVM unwinder instead of libgcc.

 .. option:: builtins_library

   Path to the builtins library to use instead of libgcc.


 Environment Variables
 ---------------------

 .. envvar:: LIBCXX_SITE_CONFIG=<path/to/lit.site.cfg>

   Specify the site configuration to use when running the tests.
   Also see `libcxx_site_config`.

 .. envvar:: LIBCXX_COLOR_DIAGNOSTICS

   If ``LIBCXX_COLOR_DIAGNOSTICS`` is defined then the test suite will attempt
   to use color diagnostic outputs from the compiler.
   Also see `color_diagnostics`.

 Benchmarks
 ==========

 Libc++ contains benchmark tests separately from the test of the test suite.
 The benchmarks are written using the `Google Benchmark`_ library, a copy of which
 is stored in the libc++ repository.

 For more information about using the Google Benchmark library see the
 `official documentation <https://github.com/google/benchmark>`_.

 .. _`Google Benchmark`: https://github.com/google/benchmark

 Building Benchmarks
 -------------------

 The benchmark tests are not built by default. The benchmarks can be built using
 the ``cxx-benchmarks`` target.

 An example build would look like:

 .. code-block:: bash

   $ cd build
   $ cmake [options] <path to libcxx sources>
   $ make cxx-benchmarks

 This will build all of the benchmarks under ``<libcxx-src>/benchmarks`` to be
 built against the just-built libc++. The compiled tests are output into
 ``build/benchmarks``.

 The benchmarks can also be built against the platforms native standard library
 using the ``-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON`` CMake option. This
 is useful for comparing the performance of libc++ to other standard libraries.
 The compiled benchmarks are named ``<test>.libcxx.out`` if they test libc++ and
 ``<test>.native.out`` otherwise.

 Also See:

   * :ref:`Building Libc++ <build instructions>`
   * :ref:`CMake Options`

 Running Benchmarks
 ------------------

 The benchmarks must be run manually by the user. Currently there is no way
 to run them as part of the build.

 For example:

 .. code-block:: bash

   $ cd build/benchmarks
   $ make cxx-benchmarks
   $ ./algorithms.libcxx.out # Runs all the benchmarks
   $ ./algorithms.libcxx.out --benchmark_filter=BM_Sort.* # Only runs the sort benchmarks

 For more information about running benchmarks see `Google Benchmark`_.
	==============
	Testing libc++
	==============

	.. contents::
	:local:

	Getting Started
	===============

	libc++ uses LIT to configure and run its tests.

	The primary way to run the libc++ tests is by using `make check-libcxx`.

	However since libc++ can be used in any number of possible
	configurations it is important to customize the way LIT builds and runs
	the tests. This guide provides information on how to use LIT directly to
	test libc++.

	Please see the `Lit Command Guide`_ for more information about LIT.

	.. _LIT Command Guide: http://llvm.org/docs/CommandGuide/lit.html

	Setting up the Environment
	--------------------------

	After building libc++ you must setup your environment to test libc++ using
	LIT.

	#. Create a shortcut to the actual lit executable so that you can invoke it
	easily from the command line.

	.. code-block:: bash

	$ alias lit='python path/to/llvm/utils/lit/lit.py'

	#. Tell LIT where to find your build configuration.

	.. code-block:: bash

	$ export LIBCXX_SITE_CONFIG=path/to/build-libcxx/test/lit.site.cfg

	Example Usage
	-------------

	Once you have your environment set up and you have built libc++ you can run
	parts of the libc++ test suite by simply running `lit` on a specified test or
	directory. For example:

	.. code-block:: bash

	$ cd path/to/src/libcxx
	$ lit -sv test/std/re # Run all of the std::regex tests
	$ lit -sv test/std/depr/depr.c.headers/stdlib_h.pass.cpp # Run a single test
	$ lit -sv test/std/atomics test/std/threads # Test std::thread and std::atomic

	Sometimes you'll want to change the way LIT is running the tests. Custom options
	can be specified using the `--param=<name>=<val>` flag. The most common option
	you'll want to change is the standard dialect (ie -std=c++XX). By default the
	test suite will select the newest C++ dialect supported by the compiler and use
	that. However if you want to manually specify the option like so:

	.. code-block:: bash

	$ lit -sv test/std/containers # Run the tests with the newest -std
	$ lit -sv --param=std=c++03 test/std/containers # Run the tests in C++03

	Occasionally you'll want to add extra compile or link flags when testing.
	You can do this as follows:

	.. code-block:: bash

	$ lit -sv --param=compile_flags='-Wcustom-warning'
	$ lit -sv --param=link_flags='-L/custom/library/path'

	Some other common examples include:

	.. code-block:: bash

	# Specify a custom compiler.
	$ lit -sv --param=cxx_under_test=/opt/bin/g++ test/std

	# Enable warnings in the test suite
	$ lit -sv --param=enable_warnings=true test/std

	# Use UBSAN when running the tests.
	$ lit -sv --param=use_sanitizer=Undefined


	LIT Options
	===========

	:program:`lit` [options...] [filenames...]

	Command Line Options
	--------------------

	To use these options you pass them on the LIT command line as --param NAME or
	--param NAME=VALUE. Some options have default values specified during CMake's
	configuration. Passing the option on the command line will override the default.

	.. program:: lit

	.. option:: cxx_under_test=<path/to/compiler>

	Specify the compiler used to build the tests.

	.. option:: cxx_stdlib_under_test=<stdlib name>

	Values: libc++, libstdc++

	Specify the C++ standard library being tested. Unless otherwise specified
	libc++ is used. This option is intended to allow running the libc++ test
	suite against other standard library implementations.

	.. option:: std=<standard version>

	Values: c++98, c++03, c++11, c++14, c++17, c++2a

	Change the standard version used when building the tests.

	.. option:: libcxx_site_config=<path/to/lit.site.cfg>

	Specify the site configuration to use when running the tests. This option
	overrides the environment variable LIBCXX_SITE_CONFIG.

	.. option:: cxx_headers=<path/to/headers>

	Specify the c++ standard library headers that are tested. By default the
	headers in the source tree are used.

	.. option:: cxx_library_root=<path/to/lib/>

	Specify the directory of the libc++ library to be tested. By default the
	library folder of the build directory is used. This option cannot be used
	when use_system_cxx_lib is provided.


	.. option:: cxx_runtime_root=<path/to/lib/>

	Specify the directory of the libc++ library to use at runtime. This directory
	is not added to the linkers search path. This can be used to compile tests
	against one version of libc++ and run them using another. The default value
	for this option is `cxx_library_root`.

	.. option:: use_system_cxx_lib=<bool>

	Default: False

	Enable or disable testing against the installed version of libc++ library.
	Note: This does not use the installed headers.

	.. option:: use_lit_shell=<bool>

	Enable or disable the use of LIT's internal shell in ShTests. If the
	environment variable LIT_USE_INTERNAL_SHELL is present then that is used as
	the default value. Otherwise the default value is True on Windows and False
	on every other platform.

	.. option:: compile_flags="<list-of-args>"

	Specify additional compile flags as a space delimited string.
	Note: This options should not be used to change the standard version used.

	.. option:: link_flags="<list-of-args>"

	Specify additional link flags as a space delimited string.

	.. option:: debug_level=<level>

	Values: 0, 1

	Enable the use of debug mode. Level 0 enables assertions and level 1 enables
	assertions and debugging of iterator misuse.

	.. option:: use_sanitizer=<sanitizer name>

	Values: Memory, MemoryWithOrigins, Address, Undefined

	Run the tests using the given sanitizer. If LLVM_USE_SANITIZER was given when
	building libc++ then that sanitizer will be used by default.

	.. option:: color_diagnostics

	Enable the use of colorized compile diagnostics. If the color_diagnostics
	option is specified or the environment variable LIBCXX_COLOR_DIAGNOSTICS is
	present then color diagnostics will be enabled.

	.. option:: llvm_unwinder

	Enable the use of LLVM unwinder instead of libgcc.

	.. option:: builtins_library

	Path to the builtins library to use instead of libgcc.


	Environment Variables
	---------------------

	.. envvar:: LIBCXX_SITE_CONFIG=<path/to/lit.site.cfg>

	Specify the site configuration to use when running the tests.
	Also see `libcxx_site_config`.

	.. envvar:: LIBCXX_COLOR_DIAGNOSTICS

	If ``LIBCXX_COLOR_DIAGNOSTICS`` is defined then the test suite will attempt
	to use color diagnostic outputs from the compiler.
	Also see `color_diagnostics`.

	Benchmarks
	==========

	Libc++ contains benchmark tests separately from the test of the test suite.
	The benchmarks are written using the `Google Benchmark`_ library, a copy of which
	is stored in the libc++ repository.

	For more information about using the Google Benchmark library see the
	`official documentation <https://github.com/google/benchmark>`_.

	.. _`Google Benchmark`: https://github.com/google/benchmark

	Building Benchmarks
	-------------------

	The benchmark tests are not built by default. The benchmarks can be built using
	the ``cxx-benchmarks`` target.

	An example build would look like:

	.. code-block:: bash

	$ cd build
	$ cmake [options] <path to libcxx sources>
	$ make cxx-benchmarks

	This will build all of the benchmarks under ``<libcxx-src>/benchmarks`` to be
	built against the just-built libc++. The compiled tests are output into
	``build/benchmarks``.

	The benchmarks can also be built against the platforms native standard library
	using the ``-DLIBCXX_BUILD_BENCHMARKS_NATIVE_STDLIB=ON`` CMake option. This
	is useful for comparing the performance of libc++ to other standard libraries.
	The compiled benchmarks are named ``<test>.libcxx.out`` if they test libc++ and
	``<test>.native.out`` otherwise.

	Also See:

	* :ref:`Building Libc++ <build instructions>`
	* :ref:`CMake Options`

	Running Benchmarks
	------------------

	The benchmarks must be run manually by the user. Currently there is no way
	to run them as part of the build.

	For example:

	.. code-block:: bash

	$ cd build/benchmarks
	$ make cxx-benchmarks
	$ ./algorithms.libcxx.out # Runs all the benchmarks
	$ ./algorithms.libcxx.out --benchmark_filter=BM_Sort.* # Only runs the sort benchmarks

	For more information about running benchmarks see `Google Benchmark`_.