bpo-40280: Address more test failures on Emscripten (GH-31050)

Co-authored-by: Brett Cannon <brett@python.org>

Author: tiran

Lib/test/support/__init__.py

@@ -1278,6 +1278,8 @@ def reap_children():
     # Need os.waitpid(-1, os.WNOHANG): Windows is not supported
     if not (hasattr(os, 'waitpid') and hasattr(os, 'WNOHANG')):
         return
+    elif not has_subprocess_support:
+        return
 
     # Reap all our dead child processes so we don't leave zombies around.
     # These hog resources and might be causing some of the buildbots to die.

Lib/test/support/os_helper.py

@@ -502,7 +502,7 @@ def __fspath__(self):
 def fd_count():
     """Count the number of open file descriptors.
     """
-    if sys.platform.startswith(('linux', 'freebsd')):
+    if sys.platform.startswith(('linux', 'freebsd', 'emscripten')):
         try:
             names = os.listdir("/proc/self/fd")
             # Subtract one because listdir() internally opens a file

Lib/test/test_builtin.py

@@ -393,6 +393,7 @@ def test_compile_top_level_await_no_coro(self):
                                 msg=f"source={source} mode={mode}")
 
 
+    @unittest.skipIf(support.is_emscripten, "socket.accept is broken")
     def test_compile_top_level_await(self):
         """Test whether code some top level await can be compiled.
 
@@ -1213,6 +1214,7 @@ def test_open_default_encoding(self):
             os.environ.clear()
             os.environ.update(old_environ)
 
+    @support.requires_subprocess()
     def test_open_non_inheritable(self):
         fileobj = open(__file__, encoding="utf-8")
         with fileobj:

Lib/test/test_capi.py

@@ -611,6 +611,7 @@ def check_fatal_error(self, code, expected, not_expected=()):
             self.assertNotIn(name, modules)
         self.assertEqual(len(modules), total)
 
+    @support.requires_subprocess()
     def test_fatal_error(self):
         # By default, stdlib extension modules are ignored,
         # but not test modules.
@@ -880,6 +881,7 @@ class Test_testinternalcapi(unittest.TestCase):
                     if name.startswith('test_'))
 
 
+@support.requires_subprocess()
 class PyMemDebugTests(unittest.TestCase):
     PYTHONMALLOC = 'debug'
     # '0x04c06e0' or '04C06E0'

Lib/test/test_faulthandler.py

@@ -19,6 +19,9 @@
 except ImportError:
     _testcapi = None
 
+if not support.has_subprocess_support:
+    raise unittest.SkipTest("test module requires subprocess")
+
 TIMEOUT = 0.5
 MS_WINDOWS = (os.name == 'nt')
 

Lib/test/test_fileio.py

@@ -9,7 +9,7 @@
 from weakref import proxy
 from functools import wraps
 
-from test.support import cpython_only, swap_attr, gc_collect
+from test.support import cpython_only, swap_attr, gc_collect, is_emscripten
 from test.support.os_helper import (TESTFN, TESTFN_UNICODE, make_bad_fd)
 from test.support.warnings_helper import check_warnings
 from collections import UserList
@@ -373,7 +373,7 @@ def testAbles(self):
             self.assertEqual(f.isatty(), False)
             f.close()
 
-            if sys.platform != "win32":
+            if sys.platform != "win32" and not is_emscripten:
                 try:
                     f = self.FileIO("/dev/tty", "a")
                 except OSError:

Lib/test/test_genericalias.py

@@ -24,14 +24,20 @@
 from fileinput import FileInput
 from itertools import chain
 from http.cookies import Morsel
-from multiprocessing.managers import ValueProxy
-from multiprocessing.pool import ApplyResult
+try:
+    from multiprocessing.managers import ValueProxy
+    from multiprocessing.pool import ApplyResult
+    from multiprocessing.queues import SimpleQueue as MPSimpleQueue
+except ImportError:
+    # _multiprocessing module is optional
+    ValueProxy = None
+    ApplyResult = None
+    MPSimpleQueue = None
 try:
     from multiprocessing.shared_memory import ShareableList
 except ImportError:
     # multiprocessing.shared_memory is not available on e.g. Android
     ShareableList = None
-from multiprocessing.queues import SimpleQueue as MPSimpleQueue
 from os import DirEntry
 from re import Pattern, Match
 from types import GenericAlias, MappingProxyType, AsyncGeneratorType
@@ -79,13 +85,14 @@ class BaseTest(unittest.TestCase):
                      Queue, SimpleQueue,
                      _AssertRaisesContext,
                      SplitResult, ParseResult,
-                     ValueProxy, ApplyResult,
                      WeakSet, ReferenceType, ref,
-                     ShareableList, MPSimpleQueue,
+                     ShareableList,
                      Future, _WorkItem,
                      Morsel]
     if ctypes is not None:
         generic_types.extend((ctypes.Array, ctypes.LibraryLoader))
+    if ValueProxy is not None:
+        generic_types.extend((ValueProxy, ApplyResult, MPSimpleQueue))
 
     def test_subscriptable(self):
         for t in self.generic_types:

Lib/test/test_getpass.py

@@ -28,6 +28,9 @@ def test_username_priorities_of_env_values(self, environ):
             getpass.getuser()
         except ImportError: # in case there's no pwd module
             pass
+        except KeyError:
+            # current user has no pwd entry
+            pass
         self.assertEqual(
             environ.get.call_args_list,
             [mock.call(x) for x in ('LOGNAME', 'USER', 'LNAME', 'USERNAME')])

Lib/test/test_inspect.py

@@ -788,6 +788,7 @@ def test_nested_class_definition_inside_function(self):
         self.assertSourceEqual(mod2.cls213, 218, 222)
         self.assertSourceEqual(mod2.cls213().func219(), 220, 221)
 
+    @unittest.skipIf(support.is_emscripten, "socket.accept is broken")
     def test_nested_class_definition_inside_async_function(self):
         import asyncio
         self.addCleanup(asyncio.set_event_loop_policy, None)

Lib/test/test_interpreters.py

@@ -5,7 +5,8 @@
 import unittest
 import time
 
-import _xxsubinterpreters as _interpreters
+from test.support import import_helper
+_interpreters = import_helper.import_module('_xxsubinterpreters')
 from test.support import interpreters