Google Mock CMake Macros

Status

Travis CI (Ubuntu)	AppVeyor (Windows)	Coverage	Biicode	Licence

Usage

This macro accommodates the various different ways Google Test and Google Mock can be found or built on different Linux and Unix Distributions. The five supported mechanisms are:

• Google Test and Google Mock installed system wide in library form.
• Google Mock installed system wide in library form, Google Test sources available on the system.
• Google Mock and Google Test sources available on the system.
• Neither Google Mock nor Google Test sources available on the system, built as an external project.
• As already specified by a parent project.

Pre-installed Google Test and Google Mock

gmock-cmake supports the use of a pre-built and pre-installed version of Google Test and Google Mock and will do so by default. Very few distributions ship pre-installed versions of Google Test and Google Mock. If a distribution does do this, then it is for reasons for policy and library consistency, as well as build and packaging convenience.

However, there are some very important caveats that should be noted. In particular, due to the operation of the One-Definition Rule, it isn't safe to deviate from the compiler flags that your distribution used to compile Google Test or Google Mock. Generally speaking, there won't be any special compiler flags passed by your distributor.

If you need to change the behavior of Google Test or Google Mock, particularly by changing default compiler flags, then you should consider forcing an in- source build. This can be done by toggling the following options from OFF to ON.

• GTEST_PREFER_SOURCE_BUILD
• GMOCK_PREFER_SOURCE_BUILD

Building Google Test and Google Mock from Source

For the reasons specified above, if your distribution ships a source version of Google Test or Google Mock, then gmock-cmake will prefer to use that than downloading a fresh copy of the sources in an external project.

Be aware that these source versions may be out of date and may not support all the functionality of C++11/C++14 in your APIs. In particular, Google Mock only implemented support for rvalue references in revision 467.

If you want to ensure that the source code for Google Test and Google Mock is always downloaded, the following options may be of use:

• GMOCK_ALWAYS_DOWNLOAD_SOURCES : Set to ON to always create an External Project and download and build sources at build time.
• GMOCK_DOWNLOAD_VERSION : If downloading sources, this can be set to either SVN or 1.7.0 and indicates the version to download.
• GMOCK_FORCE_UPDATE: If downloading the SVN version, this will cause svn up to be run on the next build.

Importing Google Test and Google Mock from a parent project

If you choose to build an external project which also uses gmock-cmake to download and build Google Test and Google Mock, then it would be convenient if they can use the same built libraries. Note above the effect of the One-Definition Rule on choosing to use a single library between two projects.

External projects built using CMake can have their cache pre-configured before running CMake. gmock-cmake provides a mechanism to populate the cache using gmock_get_forward_variables. When run after using find_package with FindGMOCK to find a copy of Google Test and Google Mock, this will provide the correct cache namespaces and dependencies to pass' to the External Project.

The External Project will then not need to compile Google Test or Google Mock.