test updates per review

Author: WardBrian

Lib/test/test_ctypes/test_dllist.py

@@ -1,57 +1,58 @@
 import os
 import sys
-import test.support
 import unittest
 from ctypes import CDLL
-from ctypes.util import dllist
+import ctypes.util
 from test.support import import_helper
 
 
-WINDOWS = os.name == 'nt'
+WINDOWS = os.name == "nt"
 APPLE = sys.platform in {"darwin", "ios", "tvos", "watchos"}
 
 if WINDOWS:
-    KNOWN_LIBRARIES = ['KERNEL32.DLL']
+    KNOWN_LIBRARIES = ["KERNEL32.DLL"]
 elif APPLE:
-    KNOWN_LIBRARIES = ['libSystem.B.dylib']
+    KNOWN_LIBRARIES = ["libSystem.B.dylib"]
 else:
     # trickier than it seems, because libc may not be present
     # on musl systems, and sometimes goes by different names.
     # However, ctypes itself loads libffi
-    KNOWN_LIBRARIES = ['libc.so', 'libffi.so']
+    KNOWN_LIBRARIES = ["libc.so", "libffi.so"]
 
+
+@unittest.skipUnless(
+    hasattr(ctypes.util, "dllist"),
+    "ctypes.util.dllist is not available on this platform",
+)
 class ListSharedLibraries(unittest.TestCase):
 
     def test_lists_system(self):
-        dlls = dllist()
-
-        self.assertIsNotNone(dlls)
-        self.assertGreater(len(dlls), 0, f'loaded={dlls}')
-        self.assertTrue(any(lib in dll for dll in dlls for lib in KNOWN_LIBRARIES), f'loaded={dlls}')
+        dlls = ctypes.util.dllist()
 
+        self.assertGreater(len(dlls), 0, f"loaded={dlls}")
+        self.assertTrue(
+            any(lib in dll for dll in dlls for lib in KNOWN_LIBRARIES), f"loaded={dlls}"
+        )
 
     def test_lists_updates(self):
-        dlls = dllist()
-
-        if dlls is not None:
-            if any("_ctypes_test" in dll for dll in dlls):
-                self.skipTest("Test library is already loaded")
+        dlls = ctypes.util.dllist()
 
-            _ctypes_test = import_helper.import_module("_ctypes_test")
-            test_module = CDLL(_ctypes_test.__file__)
-            dlls2 = dllist()
-            self.assertIsNotNone(dlls2)
+        # this test relies on being able to import a library which is
+        # not already loaded.
+        # If it is (e.g. by a previous test in the same process), we skip
+        if any("_ctypes_test" in dll for dll in dlls):
+            self.skipTest("Test library is already loaded")
 
-            dlls1 = set(dlls)
-            dlls2 = set(dlls2)
-            if test.support.verbose:
-                print("Newly loaded shared libraries:")
-                for dll in (dlls2 - dlls1):
-                    print("\t", dll)
+        _ctypes_test = import_helper.import_module("_ctypes_test")
+        test_module = CDLL(_ctypes_test.__file__)
+        dlls2 = ctypes.util.dllist()
+        self.assertIsNotNone(dlls2)
 
-            self.assertGreater(dlls2, dlls1)
-            self.assertTrue(any("_ctypes_test" in dll for dll in dlls2))
+        dlls1 = set(dlls)
+        dlls2 = set(dlls2)
 
+        self.assertGreater(dlls2, dlls1, f"newly loaded libraries: {dlls2 - dlls1}")
+        self.assertTrue(any("_ctypes_test" in dll for dll in dlls2), f"loaded={dlls2}")
 
 
 if __name__ == "__main__":