Replace gtest with sytem version

[jspricke]

• Add new FindGtest.cmake to find installed versions.
• Add libgtest-dev for Travis

[taketwo]

Works well on my machine. Seems that on Travis everything is fine also.

Shall we wait for someone on Mac to comment?

[jspricke]

Yes, @gcasey can you do this?

[gcasey]

Yes I will test this evening.

[gcasey]

Neither macports nor homebrew provide a system version of gtest for the reasons mentioned in the google test FAQ (to ensure tests are compiled with identical compiler flags)

https://trac.macports.org/ticket/35540
Homebrew/legacy-homebrew#14099

I could manually compile the package on mac and test, but I believe that we should stick with embedded version of gtest. This will also make testing easier for windows developers.

Other projects embedding gtest source code

• ceres solver - https://ceres-solver.googlesource.com/ceres-solver/+/master/internal/ceres/gtest
• google protobuf - https://code.google.com/p/protobuf/source/browse/#svn%2Ftags%2F2.0.3%2Fsrc%2Fgtest

[jspricke]

On 9. Juni 2014 16:37:35 MESZ, Casey Goodlett notifications@github.com wrote:

Neither macports nor homebrew provide a system version of gtest for
the reasons mentioned in the google test FAQ (to ensure tests are
compiled with identical compiler flags)

Neither does Debian, they only packaged the source. It should be enough to download the GTest source and add a -DGTEST_DIR=path to cmake.

[gcasey]

ok. I misunderstood based on the modification to the travis file.

I pointed my mac ( mavericks + xcode 5.1.1 ) build to the gtest source code by specifying GTEST_SRC_DIR and GTEST_INCLUDE_DIR during ccmake. I was able to build and run tests successfully.

This looks good to me.

Thanks

[jspricke]

@gcasey thanks for testing, it should work by only setting GTEST_ROOT, sorry for mixing that up.