gpg: allow dependency injection for subprocess module

trezor_agent/gpg/keyring.py

@@ -13,10 +13,10 @@ from .. import util
 log = logging.getLogger(__name__)
 
 
-def connect_to_agent(sock_path='~/.gnupg/S.gpg-agent'):
+def connect_to_agent(sock_path='~/.gnupg/S.gpg-agent', sp=subprocess):
     """Connect to GPG agent's UNIX socket."""
     sock_path = os.path.expanduser(sock_path)
-    subprocess.check_call(['gpg-connect-agent', '/bye'])
+    sp.check_call(['gpg-connect-agent', '/bye'])
     sock = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)
     sock.connect(sock_path)
     return sock
@@ -105,14 +105,14 @@ def parse_sig(sig):
     return parser(args=sig[1:])
 
 
-def sign_digest(sock, keygrip, digest):
+def sign_digest(sock, keygrip, digest, sp=subprocess):
     """Sign a digest using specified key using GPG agent."""
     hash_algo = 8  # SHA256
     assert len(digest) == 32
 
     assert _communicate(sock, 'RESET').startswith(b'OK')
 
-    ttyname = subprocess.check_output('tty').strip()
+    ttyname = sp.check_output(['tty']).strip()
     options = ['ttyname={}'.format(ttyname)]  # set TTY for passphrase entry
 
     display = os.environ.get('DISPLAY')
@@ -143,17 +143,17 @@ def sign_digest(sock, keygrip, digest):
     return parse_sig(sig)
 
 
-def get_keygrip(user_id):
+def get_keygrip(user_id, sp=subprocess):
     """Get a keygrip of the primary GPG key of the specified user."""
     args = ['gpg2', '--list-keys', '--with-keygrip', user_id]
-    output = subprocess.check_output(args).decode('ascii')
+    output = sp.check_output(args).decode('ascii')
     return re.findall(r'Keygrip = (\w+)', output)[0]
 
 
-def export_public_key(user_id):
+def export_public_key(user_id, sp=subprocess):
     """Export GPG public key for specified `user_id`."""
     args = ['gpg2', '--export'] + ([user_id] if user_id else [])
-    result = subprocess.check_output(args=args)
+    result = sp.check_output(args=args)
     if not result:
         log.error('could not find public key %r in local GPG keyring', user_id)
         raise KeyError(user_id)