According to Python documentation[1] dirname and basename
are defined as follows:
os.path.dirname() = os.path.split()[0]
os.path.basename() = os.path.split()[1]
For the purpose of better readability split() is replaced
by appropriate function if only one part of returned tuple
is used.
[1]: https://docs.python.org/3/library/os.path.html#os.path.split
When `ninja -C builddir/ test` is run, ninja will change into the build
dir before starting, but `meson test -C builddir/` does not. This is
important because meson does not use (for good reasons) absolute paths,
which means if a test case needs to be passed as an argument a file name
that is part of the build process, it will be relative builddir. Without
changing into the builddir the path will not exist (or worse, point at
the wrong thing), and test will not behave as intended.
To fix this mtest will change directory before starting tests, and will
change back after all tests have been finished.
Fixes#2710
Adding it to the end of PATH means that if an installed instance of a DLL
exists, that would be used instead of the built instance.
Compare with run_exe(), which already gets this right.