test: Add a new integration test with minor dialogs

This patch adds a new integration test, which executes various small
dialogs, to cover corner cases that are not well covered (according to
our coverage report).

For example, "EHLO" without domain, or invalid DATA.

While we could do them via Go tests, this way is more realistic, and the
tests are easier to write.

test/util/chamuyero

@@ -12,6 +12,7 @@ interactive command-line tools.
 import argparse
 import os
 import re
+import ssl
 import socket
 import subprocess
 import sys
@@ -97,6 +98,19 @@ class TCPSock (Sock):
         self.has_conn.set()
 
 
+class TLSSock (Sock):
+    def __init__(self, addr):
+        host, port = addr.rsplit(":", 1)
+        Sock.__init__(self, (host, int(port)))
+        plain_sock = socket.create_connection(self.addr)
+        self.sock = ssl.wrap_socket(plain_sock)
+
+    def connect(self):
+        self.connr = self.sock.makefile(mode="r")
+        self.connw = self.sock.makefile(mode="w")
+        self.has_conn.set()
+
+
 class Interpreter (object):
     """Interpreter for chamuyero scripts."""
     def __init__(self):
@@ -175,6 +189,11 @@ class Interpreter (object):
                 sock.connect()
                 self.procs[proc] = sock
 
+            elif op == "tls_connect":
+                sock = TLSSock(params)
+                sock.connect()
+                self.procs[proc] = sock
+
             # ->   Send to a process stdin, with a \n at the end.
             # .>   Send to a process stdin, no \n at the end.
             elif op == "->":