old_contents: import unittest
  from . import TestCase
  
  from llvmlite import binding as llvm
  from llvmlite.binding import dylib
  import platform
  
  
  class TestDylib(TestCase):
  
      def setUp(self):
          llvm.initialize()
          llvm.initialize_native_target()
          llvm.initialize_native_asmprinter()
  
      def test_bad_library(self):
          with self.assertRaises(Exception) as context:
              dylib.load_library_permanently("zzzasdkf;jasd;l")
          system = platform.system()
          if system  == "Linux":
              self.assertTrue('zzzasdkf;jasd;l: cannot open shared object file: No such file or directory'
                              in str(context.exception))
          elif system == "Darwin":
              self.assertTrue('dlopen(zzzasdkf;jasd;l, 9): image not found'
                              in str(context.exception))
  
new_contents: from . import TestCase
  
  from llvmlite import binding as llvm
  from llvmlite.binding import dylib
  import platform
  from ctypes.util import find_library
  import unittest
  
  @unittest.skipUnless(platform.system() in {"Linux", "Darwin"}, "Unsupport test for current OS")
  class TestDylib(TestCase):
      def setUp(self):
          llvm.initialize()
          llvm.initialize_native_target()
          llvm.initialize_native_asmprinter()
          self.system = platform.system()
  
      def test_bad_library(self):
          with self.assertRaises(Exception) as context:
              dylib.load_library_permanently("zzzasdkf;jasd;l")
          if self.system  == "Linux":
              self.assertTrue('zzzasdkf;jasd;l: cannot open shared object file: No such file or directory'
                              in str(context.exception))
          elif self.system == "Darwin":
              self.assertTrue('dlopen(zzzasdkf;jasd;l, 9): image not found'
                              in str(context.exception))
  
      def test_libm(self):
          try:
              if self.system  == "Linux":
                  libm = find_library("m")
              elif self.system == "Darwin":
                  libm = find_library("libm")
              dylib.load_library_permanently(libm)
          except Exception:
              self.fail("Valid call to link library should not fail.")
  
subject: Add tests to check loading library.