Fixed Channel to handle the case where ssl module is not available, c…

…loses #194

grpclib/client.py

@@ -658,10 +658,10 @@ def __init__(
             if port is None:
                 port = 50051
 
-        if ssl is not None and _ssl is None:
-            raise RuntimeError('SSL is not supported.')
-
-        if ssl is True:
+        if _ssl is None:
+            if ssl is not None:
+                raise RuntimeError('SSL is not supported')
+        elif ssl is True:
             ssl = self._get_default_ssl_context()
         elif isinstance(ssl, _ssl.DefaultVerifyPaths):
             ssl = self._get_default_ssl_context(verify_paths=ssl)

tests/test_client_channel.py

@@ -8,6 +8,7 @@
 import certifi
 from h2.connection import H2Connection
 
+import grpclib.client
 from grpclib.client import Channel, Handler
 from grpclib.config import Configuration
 from grpclib.protocol import H2Protocol
@@ -95,3 +96,11 @@ def test_default_verify_paths():
         po.assert_called_once_with(tf, td, None)
         assert default_verify_paths.openssl_cafile_env == "SSL_CERT_FILE"
         assert default_verify_paths.openssl_capath_env == "SSL_CERT_DIR"
+
+
+def test_no_ssl_support():
+    with patch.object(grpclib.client, "_ssl", None):
+        Channel()
+        with pytest.raises(RuntimeError) as err:
+            Channel(ssl=True)
+        err.match("SSL is not supported")