The algorithm was sub-optimal so replace it with something more elegant.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

ftools functions that expect data may get 'None'; this patch does this check
and return immediately if this is the case.

Signed-off-by: Leonardo Sandoval <leonardo.sandoval.gonzalez@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

There may be cases where the configuration file (path) does not exist,
thus the remove_from_file should catch this exception. In case the exception
is not the latter (errno.ENOENT), then re-raise it.

[YOCTO #8540]

Signed-off-by: Leonardo Sandoval <leonardo.sandoval.gonzalez@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

The purpose of oe-selftest is to run unittest modules added from meta/lib/oeqa/selftest,
which are tests against bitbake tools.

Right now the script it's useful for simple tests like:
  - "bitbake --someoption, change some metadata, bitbake X, check something" type scenarios (PR service, error output, etc)
  - or "bitbake-layers <...>" type scripts and yocto-bsp tools.

This commit also adds some helper modules that the tests will use and a base class.
Also, most of the tests will have a dependency on a meta-selftest layer
which contains specially modified recipes/bbappends/include files for the purpose of the tests.
The tests themselves will usually write to ".inc" files from the layer or in conf/selftest.inc
(which is added as an include in local.conf at the start and removed at the end)

It's a simple matter or sourcing the enviroment, adding the meta-selftest layer to bblayers.conf
and running: oe-selftest to get some results. It would finish faster if at least a core-image-minimal
was built before.

[ YOCTO #4740 ]

Signed-off-by: Stefan Stanacar <stefanx.stanacar@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>