test_sysconfig.test_ldshared_value is failing for me on Mac because my LDFLAGS environment variable is being defined twice in what sysconfig.get_config_var('LDFLAGS') returns. This fails in a comparison against sysconfig.get_config_var('LDSHARED') as the values are only set once::

AssertionError: '-L/Users/brett/.slash/_/lib -L/Users/brett/.local/lib  -L/Users/brett/.slash/_/lib -L/Users/brett/.local/lib' not found in 'clang  -L/Users/brett/.slash/_/lib -L/Users/brett/.local/lib -bundle -undefined dynamic_lookup'

I suspect what is happening is sysconfig is using PY_LDFLAGS, which uses both CONFIGURE_LDFLAGS *and* LDFLAGS when the Makefile is run. This leads to LDFLAGS being set twice if it was pulled from the user's environment variable