Install gflags

Linux:

$ sudo apt-get install libgflags-dev

OS X:

$ brew install gflags

Download googletest

$ curl -O https://googletest.googlecode.com/files/gtest-1.7.0.zip
$ unzip gtest-1.7.0.zip

Download and build google benchmark

$ git clone https://github.com/google/benchmark
$ cd benchmark
$ cmake . -DCMAKE_BUILD_TYPE=Release
$ make
$ sudo make install

Build s2-geometry-library and run tests

$ cd geometry
$ GTEST_DIR=/path/to/gtest-1.7.0 make
$ GTEST_DIR=/path/to/gtest-1.7.0 make test
$ GTEST_DIR=/path/to/gtest-1.7.0 make bench