pylightning - allow unicode symbols in the description to be passed as-is to the daemon

addresses issue #2753.

Formatting the JSON with the default parameters will escape the unicode
symbols in a way that c-lightning won't allow, leading to an exception.

Changelog-Fixed: `pylightning` now handles unicode characters in JSON-RPC requests and responses correctly.

contrib/pyln-client/pyln/client/lightning.py

@@ -172,7 +172,7 @@ class UnixDomainSocketRpc(object):
         self.next_id = 0
 
     def _writeobj(self, sock, obj):
-        s = json.dumps(obj, cls=self.encoder_cls)
+        s = json.dumps(obj, ensure_ascii=False, cls=self.encoder_cls)
         sock.sendall(bytearray(s, 'UTF-8'))
 
     def _readobj(self, sock, buff=b''):

tests/test_misc.py

@@ -2000,7 +2000,6 @@ def test_new_node_is_mainnet(node_factory):
     assert os.path.isfile(os.path.join(basedir, "lightningd-bitcoin.pid"))
 
 
-@pytest.mark.xfail(strict=True)
 def test_unicode_rpc(node_factory):
     node = node_factory.get_node()
     desc = "Some candy 🍬 and a nice glass of milk 🥛."