Instead of unconditionally attempting to clone from a fixed location
(GitHub) during the build / test process, honor the following two
configuration variables:
TOML11_LANGSPEC_GIT_REPOSITORY
Can be set to override the URL from which the repository is cloned.
This allows using a local mirror, including file:// URLs for working
offline or reducing network traffic.
TOML11_LANGSPEC_SOURCE_DIR
Can be set to configure the location at which the repository is
expected. If it already exists no download will be attempted. This
allows avoiding the additional git-clone(1) altogether and use an
existing directory as-is. This offers two new possibilities:
(1) The same checkout can be reused for building multiple
configurations (e.g. Debug versus Release) saving a little bit of
time and disk space.
(2) Experimental changes can easily be applied to the local source
tree without having them destroyed by the build process.
In order for this flexible location to work, the unit tests which
attempt to read files from the repository had to be adjusted. They now
honor an environment variable TOMLDIR which can be set to point to an
alternate root directory.
All defaults are set such that the previous behavior is maintained.
Instead of introducing the TOMLDIR environment variable, an alternative
solution would have been to set the WORKING_DIRECTORY of the tests to
the TOML11_LANGSPEC_SOURCE_DIR and leave the relative paths in these
tests hard-coded. Alas, some tests also expect that they can /write/
into the current working directory which isn't desirable if it is
potentially pointing outside the build tree. I personally prefer to
mount the source directory read-only and build in a fast tempfs, so this
would e a problem. To be perfectly honest, I don't quite understand why
these tests need to write to the file system in the first place, though.
It seems to me that refactoring them to serialize to a std::ostrstream
instead of a std::ofstream would not only simplify but also speed up the
unit tests and avoid file system problems. But there might have been a
hidden reason why actually using the real file system was considered
necessary for these tests, so I didn't went ahead with that change yet.
The conditional inclusion of either the library or the header-only
version of the Boost.Test header wasn't tremendously useful in practice
because the tests/CMakeLists.txt file would unconditionally add compile
definitions to basically fore dynamic linking.
This patch adds feature detection to the tests/CMakeLists.txt file to
determine whether to use dynamic linking, static linking or the
header-only version (in that order of preference, for best performance).
The automatic detection could be overridden if needed by defining the
TOML11_WITH_BOOST_TEST_{HEADER,STATIC,DYNAMIC}
variables on the CMake command line.
While we are at it, instead of having a conditional
#define BOOST_TEST_NO_LIB
in each unit test file, handle this once in the CMakeLists.txt file.
