bpo-31904: Disable os.popen and popen test cases on VxWorks (GH-21687)

Doc/library/os.rst

@@ -32,7 +32,7 @@ Notes on the availability of these functions:
   objects, and result in an object of the same type, if a path or file name is
   returned.
 
-* On VxWorks, os.fork, os.execv and os.spawn*p* are not supported.
+* On VxWorks, os.popen, os.fork, os.execv and os.spawn*p* are not supported.
 
 .. note::
 

Lib/os.py

@@ -36,7 +36,7 @@ _names = sys.builtin_module_names
 __all__ = ["altsep", "curdir", "pardir", "sep", "pathsep", "linesep",
            "defpath", "name", "path", "devnull", "SEEK_SET", "SEEK_CUR",
            "SEEK_END", "fsencode", "fsdecode", "get_exec_path", "fdopen",
-           "popen", "extsep"]
+           "extsep"]
 
 def _exists(name):
     return name in globals()
@@ -969,7 +969,9 @@ otherwise return -SIG, where SIG is the signal that killed it. """
 
     __all__.extend(["spawnlp", "spawnlpe"])
 
-
+# VxWorks has no user space shell provided. As a result, running
+# command in a shell can't be supported.
+if sys.platform != 'vxworks':
     # Supply os.popen()
     def popen(cmd, mode="r", buffering=-1):
         if not isinstance(cmd, str):
@@ -1015,6 +1017,8 @@ class _wrap_close:
         def __iter__(self):
             return iter(self._stream)
 
+    __all__.append("popen")
+
 # Supply os.fdopen()
 def fdopen(fd, *args, **kwargs):
     if not isinstance(fd, int):

Lib/test/test_os.py

@@ -991,6 +991,7 @@ class EnvironTests(mapping_tests.BasicTestMappingProtocol):
     # Bug 1110478
     @unittest.skipUnless(unix_shell and os.path.exists(unix_shell),
                          'requires a shell')
+    @unittest.skipUnless(hasattr(os, 'popen'), "needs os.popen()")
     def test_update2(self):
         os.environ.clear()
         os.environ.update(HELLO="World")
@@ -1000,6 +1001,7 @@ class EnvironTests(mapping_tests.BasicTestMappingProtocol):
 
     @unittest.skipUnless(unix_shell and os.path.exists(unix_shell),
                          'requires a shell')
+    @unittest.skipUnless(hasattr(os, 'popen'), "needs os.popen()")
     def test_os_popen_iter(self):
         with os.popen("%s -c 'echo \"line1\nline2\nline3\"'"
                       % unix_shell) as popen:

Lib/test/test_popen.py

@@ -7,6 +7,9 @@ import unittest
 from test import support
 import os, sys
 
+if not hasattr(os, 'popen'):
+    raise unittest.SkipTest("need os.popen()")
+
 # Test that command-lines get down as we expect.
 # To do this we execute:
 #    python -c "import sys;print(sys.argv)" {rest_of_commandline}

Lib/test/test_posix.py

@@ -1045,6 +1045,7 @@ class PosixTester(unittest.TestCase):
 
 
     @unittest.skipUnless(hasattr(os, 'getegid'), "test needs os.getegid()")
+    @unittest.skipUnless(hasattr(os, 'popen'), "test needs os.popen()")
     def test_getgroups(self):
         with os.popen('id -G 2>/dev/null') as idg:
             groups = idg.read().strip()

Lib/test/test_select.py

@@ -46,6 +46,7 @@ class SelectTestCase(unittest.TestCase):
         self.assertIsNot(r, x)
         self.assertIsNot(w, x)
 
+    @unittest.skipUnless(hasattr(os, 'popen'), "need os.popen()")
     def test_select(self):
         code = textwrap.dedent('''
             import time

Misc/NEWS.d/next/Tests/2020-07-30-18-06-15.bpo-31904.y3d8dk.rst

@@ -0,0 +1 @@
+Disable os.popen and impacted tests on VxWorks