pytest: Add a new RPC interface to talk to grpc

This allows us to re-use existing tests (assuming the call and fields
are covered by `cln-rpc` and `cln-grpc`) to test the full roundtrip
from test over the grpc interface to the json-rpc interface and back
again.

You can switch to the grpc interface by setting the `CLN_TEST_GRPC`
environment variable to 1, but for now only very few shims are
implemented (due to the non-generated nature of LightningRpc).

contrib/pyln-testing/pyln/testing/grpc.py

@@ -0,0 +1,84 @@
+"""A drop-in replacement for the JSON-RPC LightningRpc
+"""
+
+from pyln.testing import node_pb2_grpc as pbgrpc
+from pyln.testing import node_pb2 as pb
+import grpc
+import json
+from google.protobuf.json_format import MessageToJson
+from pyln.testing import grpc2py
+
+
+DUMMY_CA_PEM = b"""-----BEGIN CERTIFICATE-----
+MIIBcTCCARigAwIBAgIJAJhah1bqO05cMAoGCCqGSM49BAMCMBYxFDASBgNVBAMM
+C2NsbiBSb290IENBMCAXDTc1MDEwMTAwMDAwMFoYDzQwOTYwMTAxMDAwMDAwWjAW
+MRQwEgYDVQQDDAtjbG4gUm9vdCBDQTBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IA
+BPF4JrGsOsksgsYM1NNdUdLESwOxkzyD75Rnj/g7sFEVYXewcmyB3MRGCBx2a3/7
+ft2Xu2ED6WigajaHlnSvfUyjTTBLMBkGA1UdEQQSMBCCA2NsboIJbG9jYWxob3N0
+MB0GA1UdDgQWBBRcTjvqVodamGirO6sX1rOR02LwXzAPBgNVHRMBAf8EBTADAQH/
+MAoGCCqGSM49BAMCA0cAMEQCICDvV5iFw/nmJdl6rlEEGAdBdZqjxD0tV6U/FvuL
+7PycAiASEMtsFtpfiUvxveBkOGt7AN32GP/Z75l+GhYXh7L1ig==
+-----END CERTIFICATE-----"""
+
+
+DUMMY_CA_KEY_PEM = b"""-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgqbU7LQsRcvmI5vE5
+MBBNK3imhIU2jmAczgvLuBi/Ys+hRANCAATxeCaxrDrJLILGDNTTXVHSxEsDsZM8
+g++UZ4/4O7BRFWF3sHJsgdzERggcdmt/+37dl7thA+looGo2h5Z0r31M
+-----END PRIVATE KEY-----"""
+
+
+DUMMY_CLIENT_KEY_PEM = b"""-----BEGIN PRIVATE KEY-----
+MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgIEdQyKso8PaD1kiz
+xxFEcKiTvTg+bej4Nc/GqnXipcGhRANCAARGoUNSnWx1qgt4RiVG8tOMX1vpKvhr
+OLcUJ92T++kIFZchZvcTXwnlNiTAQg3ukL+RYyG5Q1PaYrYRVlOtl1T0
+-----END PRIVATE KEY-----"""
+
+
+DUMMY_CLIENT_PEM = b"""-----BEGIN CERTIFICATE-----
+MIIBRDCB7KADAgECAgkA8SsXq7IZfi8wCgYIKoZIzj0EAwIwFjEUMBIGA1UEAwwL
+Y2xuIFJvb3QgQ0EwIBcNNzUwMTAxMDAwMDAwWhgPNDA5NjAxMDEwMDAwMDBaMBox
+GDAWBgNVBAMMD2NsbiBncnBjIFNlcnZlcjBZMBMGByqGSM49AgEGCCqGSM49AwEH
+A0IABEahQ1KdbHWqC3hGJUby04xfW+kq+Gs4txQn3ZP76QgVlyFm9xNfCeU2JMBC
+De6Qv5FjIblDU9pithFWU62XVPSjHTAbMBkGA1UdEQQSMBCCA2NsboIJbG9jYWxo
+b3N0MAoGCCqGSM49BAMCA0cAMEQCICTU/YAs35cb6DRdZNzO1YbEt77uEjcqMRca
+Hh6kK99RAiAKOQOkGnoAICjBmBJeC/iC4/+hhhkWZtFgbC3Jg5JD0w==
+-----END CERTIFICATE-----"""
+
+
+class LightningGrpc(object):
+    def __init__(
+        self,
+        host: str,
+        port: int,
+        root_certificates: bytes = DUMMY_CA_PEM,
+        private_key: bytes = DUMMY_CLIENT_KEY_PEM,
+        certificate_chain: bytes = DUMMY_CLIENT_PEM,
+    ):
+        self.credentials = grpc.ssl_channel_credentials(
+            root_certificates=root_certificates,
+            private_key=private_key,
+            certificate_chain=certificate_chain,
+        )
+        self.channel = grpc.secure_channel(
+            f"{host}:{port}",
+            self.credentials,
+            options=(("grpc.ssl_target_name_override", "cln"),),
+        )
+        self.stub = pbgrpc.NodeStub(self.channel)
+
+    def getinfo(self):
+        return grpc2py.getinfo2py(
+            self.stub.Getinfo(pb.GetinfoRequest())
+        )
+
+    def connect(self, peer_id, host=None, port=None):
+        """
+        Connect to {peer_id} at {host} and {port}.
+        """
+        payload = pb.ConnectRequest(
+            id=peer_id,
+            host=host,
+            port=port
+        )
+        return grpc2py.connect2py(self.stub.ConnectPeer(payload))