Add support for unix sockets and improve rpc testing

capnp/lib/capnp.pyx

@@ -2204,13 +2204,18 @@ cdef class TwoPartyClient:
         del self.thisptr
 
     cpdef _connect(self, host_string):
-        host, port = host_string.split(':')
+        if host_string.startswith('unix:'):
+            path = host_string[5:]
+            sock = _socket.socket(_socket.AF_UNIX, _socket.SOCK_STREAM)
+            sock.connect(path)
+        else:
+            host, port = host_string.split(':')
 
-        sock = _socket.create_connection((host, port))
+            sock = _socket.create_connection((host, port))
 
-        # Set TCP_NODELAY on socket to disable Nagle's algorithm. This is not
+            # Set TCP_NODELAY on socket to disable Nagle's algorithm. This is not
-        # neccessary, but it speeds things up.
+            # neccessary, but it speeds things up.
-        sock.setsockopt(_socket.IPPROTO_TCP, _socket.TCP_NODELAY, 1)
+            sock.setsockopt(_socket.IPPROTO_TCP, _socket.TCP_NODELAY, 1)
         return sock
 
     cpdef restore(self, objectId) except +reraise_kj_exception:

test/test_rpc_calculator.py

@@ -2,9 +2,12 @@ import capnp
 import os
 import socket
 import gc
+import subprocess
+import time
 
 import sys  # add examples dir to sys.path
-sys.path.append(os.path.join(os.path.dirname(__file__), '..', 'examples'))
+examples_dir = os.path.join(os.path.dirname(__file__), '..', 'examples')
+sys.path.append(examples_dir)
 import calculator_client
 import calculator_server
 
@@ -16,6 +19,31 @@ def test_calculator():
     calculator_client.main(read)
 
 
+def run_subprocesses(address):
+    server = subprocess.Popen([examples_dir + '/calculator_server.py', address])
+    time.sleep(.1)  # Give the server some small amount of time to start listening
+    client = subprocess.Popen([examples_dir + '/calculator_client.py', address])
+
+    ret = client.wait()
+    server.kill()
+    assert ret == 0
+
+
+def test_calculator_tcp():
+    address = '127.0.0.1:36431'
+    run_subprocesses(address)
+
+
+def test_calculator_unix():
+    path = '/tmp/pycapnp-test'
+    try:
+        os.unlink(path)
+    except OSError:
+        pass
+
+    address = 'unix:' + path
+    run_subprocesses(address)
+
 def test_calculator_gc():
     def new_evaluate_impl(old_evaluate_impl):
         def call(*args, **kwargs):