### Generic Build Instructions
#### Setup
To build Google Test and your tests that use it, you need to tell your build
system where to find its headers and source files. The exact way to do it
depends on which build system you use, and is usually straightforward.
#### Build
Suppose you put Google Test in directory `${GTEST_DIR}`. To build it, create a
library build target (or a project as called by Visual Studio and Xcode) to
compile
${GTEST_DIR}/src/gtest-all.cc
with `${GTEST_DIR}/include` in the system header search path and `${GTEST_DIR}`
in the normal header search path. Assuming a Linux-like system and gcc,
something like the following will do:
g++ -std=c++11 -isystem ${GTEST_DIR}/include -I${GTEST_DIR} \
-pthread -c ${GTEST_DIR}/src/gtest-all.cc
ar -rv libgtest.a gtest-all.o
(We need `-pthread` as Google Test uses threads.)
Next, you should compile your test source file with `${GTEST_DIR}/include` in
the system header search path, and link it with gtest and any other necessary
libraries:
g++ -std=c++11 -isystem ${GTEST_DIR}/include -pthread path/to/your_test.cc libgtest.a \
-o your_test
As an example, the make/ directory contains a Makefile that you can use to build
Google Test on systems where GNU make is available (e.g. Linux, Mac OS X, and
Cygwin). It doesn't try to build Google Test's own tests. Instead, it just
builds the Google Test library and a sample test. You can use it as a starting
point for your own build script.
If the default settings are correct for your environment, the following commands
should succeed:
cd ${GTEST_DIR}/make
make
./sample1_unittest
If you see errors, try to tweak the contents of `make/Makefile` to make them go
away. There are instructions in `make/Makefile` on how to do it.
### Using CMake
Google Test comes with a CMake build script (
[CMakeLists.txt](https://github.com/google/googletest/blob/master/CMakeLists.txt))
that can be used on a wide range of platforms ("C" stands for cross-platform.).
If you don't have CMake installed already, you can download it for free from
<http://www.cmake.org/>.
CMake works by generating native makefiles or build projects that can be used in
the compiler environment of your choice. You can either build Google Test as a
standalone project or it can be incorporated into an existing CMake build for
another project.
#### Standalone CMake Project
When building Google Test as a standalone project, the typical workflow starts
with:
mkdir mybuild # Create a directory to hold the build output.
cd mybuild
cmake ${GTEST_DIR} # Generate native build scripts.
If you want to build Google Test's samples, you should replace the last command
with
cmake -Dgtest_build_samples=ON ${GTEST_DIR}
If you are on a \*nix system, you should now see a Makefile in the current
directory. Just type 'make' to build gtest.
If you use Windows and have Visual Studio installed, a `gtest.sln` file and
several `.vcproj` files will be created. You can then build them using Visual
Studio.
On Mac OS X with Xcode installed, a `.xcodeproj` file will be generated.
#### Incorporating Into An Existing CMake Project
If you want to use gtest in a project which already uses CMake, then a more
robust and flexible approach is to build gtest as part of that project directly.
This is done by making the GoogleTest source code available to the main build
and adding it using CMake's `add_subdirectory()` command. This has the
significant advantage that the same compiler and linker settings are used
between gtest and the rest of your project, so issues associated with using
incompatible libraries (eg debug/release), etc. are avoided. This is
particularly useful on Windows. Making GoogleTest's source code available to the
main build can be done a few different ways:
* Download the GoogleTest source code manually and place it at a known
location. This is the least flexible approach and can make it more difficult
to use with continuous integration systems, etc.
* Embed the GoogleTest source code as a direct copy in the main project's
source tree. This is often the simplest approach, but is also the hardest to
keep up to date. Some organizations may not permit this method.
* Add GoogleTest as a git submodule or equivalent. This may not always be
possible or appropriate. Git submodules, for example, have their own set of
advantages and drawbacks.
* Use CMake to download GoogleTest as part of the build's configure step. This
is just a little more complex, but doesn't have the limitations of the other
methods.
The last of the above methods is implemented with a small piece of CMake code in
a separate file (e.g. `CMakeLists.txt.in`) which is copied to the build area and
then invoked as a sub-build _during the CMake stage_. That directory is then
pulled into the main build with `add_subdirectory()`. For example:
New file `CMakeLists.txt.in`:
``` cmake
cmake_minimum_required(VERSION 2.8.2)
project(googletest-download NONE)
include(ExternalProject)
ExternalProject_Add(googletest
GIT_REPOSITORY https://github.com/google/googletest.git
GIT_TAG master
SOURCE_DIR "${CMAKE_CURRENT_BINARY_DIR}/googletest-src"
BINARY_DIR "${CMAKE_CURRENT_BINARY_DIR}/googletest-build"
CONFIGURE_COMMAND ""
BUILD_COMMAND ""
INSTALL_COMMAND ""
TEST_COMMAND ""
)
```
Existing build's `CMakeLists.txt`:
``` cmake
# Download and unpack googletest at configure time
configure_file(CMakeLists.txt.in googletest-download/CMakeLists.txt)
execute_process(COMMAND ${CMAKE_COMMAND} -G "${CMAKE_GENERATOR}" .
RESULT_VARIABLE result
WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download )
if(result)
message(FATAL_ERROR "CMake step for googletest failed: ${result}")
endif()
execute_process(COMMAND ${CMAKE_COMMAND} --build .
RESULT_VARIABLE result
WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}/googletest-download )
if(result)
message(FATAL_ERROR "Build step for googletest failed: ${result}")
endif()
# Prevent overriding the parent project's compiler/linker
# settings on Windows
set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
# Add googletest directly to our build. This defines
# the gtest and gtest_main targets.
add_subdirectory(${CMAKE_CURRENT_BINARY_DIR}/googletest-src
${CMAKE_CURRENT_BINARY_DIR}/googletest-build
EXCLUDE_FROM_ALL)
# The gtest/gtest_main targets carry header search path
# dependencies automatically when using CMake 2.8.11 or
# later. Otherwise we have to add them here ourselves.
if (CMAKE_VERSION VERSION_LESS 2.8.11)
include_directories("${gtest_SOURCE_DIR}/include")
endif()
# Now simply link against gtest or gtest_main as needed. Eg
add_executable(example example.cpp)
target_link_libraries(example gtest_main)
add_test(NAME example_test COMMAND example)
```
Note that this approach requires CMake 2.8.2 or later due to its use of the
`ExternalProject_Add()` command. The above technique is discussed in more detail
in [this separate article](http://crascit.com/2015/07/25/cmake-gtest/) which
also contains a link to a fully generalized implementation of the technique.
##### Visual Studio Dynamic vs Static Runtimes
By default, new Visual Studio projects link the C runtimes dynamically but
Google Test links them statically. This will generate an error that looks
something like the following: gtest.lib(gtest-all.obj) : error LNK2038: mismatch
detected for 'RuntimeLibrary': value 'MTd_StaticDebug' doesn't match value
'MDd_DynamicDebug' in main.obj
Google Test already has a CMake option for this: `gtest_force_shared_crt`
Enabling this option will make gtest link the runtimes dynamically too, and
match the project in which it is included.