Handle lack of support for os.environb on some OSes (such as Windows)

asyncssh/misc.py

@@ -159,9 +159,16 @@ def lookup_env(patterns: EnvList) -> Iterator[Tuple[bytes, bytes]]:
         if isinstance(pattern, str):
             pattern = pattern.encode('utf-8')
 
-        for key_bytes, value_bytes in os.environb.items():
-            if fnmatch.fnmatch(key_bytes, pattern):
-                yield key_bytes, value_bytes
+        if os.supports_bytes_environ:
+            for key_bytes, value_bytes in os.environb.items():
+                if fnmatch.fnmatch(key_bytes, pattern):
+                    yield key_bytes, value_bytes
+        else: # pragma: no cover
+            for key, value in os.environ.items():
+                key_bytes = key.encode('utf-8')
+                value_bytes = value.encode('utf-8')
+                if fnmatch.fnmatch(key_bytes, pattern):
+                    yield key_bytes, value_bytes
 
 
 def decode_env(env: Dict[bytes, bytes]) -> Iterator[Tuple[str, str]]:

tests/test_channel.py

@@ -23,6 +23,7 @@
 import asyncio
 import os
 import tempfile
+import unittest
 from signal import SIGINT
 
 from unittest.mock import patch
@@ -1315,6 +1316,8 @@ async def test_send_env(self):
             result = ''.join(session.recv_buf[None])
             self.assertEqual(result, 'test\n')
 
+    @unittest.skipUnless(os.supports_bytes_environ,
+                         'skip binary send env if not supported by OS')
     @asynctest
     async def test_send_env_binary(self):
         """Test sending local environment using a byte string"""