Use boring old dependency injection to replace mocks in this test

src/allmydata/test/test_connections.py

@@ -190,16 +190,28 @@ class Connections(unittest.TestCase):
         self.assertEqual(default_connection_handlers["i2p"], "i2p")
 
     def test_tor_unimportable(self):
-        with mock.patch("allmydata.util.tor_provider._import_tor",
+        """
-                        return_value=None):
+        If the configuration calls for substituting Tor for TCP and
+        ``foolscap.connections.tor`` is not importable then
+        ``create_connection_handlers`` raises ``ValueError`` with a message
+        explaining this makes Tor unusable.
+        """
         self.config = config_from_string(
             "fake.port",
             "no-basedir",
             BASECONFIG + "[connections]\ntcp = tor\n",
         )
+        tor_provider = create_tor_provider(
+            reactor,
+            self.config,
+            import_tor=lambda: None,
+        )
         with self.assertRaises(ValueError) as ctx:
-                tor_provider = create_tor_provider(reactor, self.config)
+            default_connection_handlers, _ = create_connection_handlers(
-                default_connection_handlers, _ = create_connection_handlers(self.config, mock.Mock(), tor_provider)
+                self.config,
+                i2p_provider=ConstantAddresses(handler=object()),
+                tor_provider=tor_provider,
+            )
         self.assertEqual(
             str(ctx.exception),
             "'tahoe.cfg [connections] tcp='"

src/allmydata/util/tor_provider.py

@@ -17,23 +17,7 @@ from ..interfaces import (
     IAddressFamily,
 )
 
-def create(reactor, config):
-    """
-    Create a new _Provider service (this is an IService so must be
-    hooked up to a parent or otherwise started).
-
-    If foolscap.connections.tor or txtorcon are not installed, then
-    Provider.get_tor_handler() will return None.  If tahoe.cfg wants
-    to start an onion service too, then this `create()` method will
-    throw a nice error (and startService will throw an ugly error).
-    """
-    provider = _Provider(config, reactor)
-    provider.check_onion_config()
-    return provider
-
-
 def _import_tor():
-    # this exists to be overridden by unit tests
     try:
         from foolscap.connections import tor
         return tor
@@ -47,6 +31,25 @@ def _import_txtorcon():
     except ImportError: # pragma: no cover
         return None
 
+def create(reactor, config, import_tor=None, import_txtorcon=None):
+    """
+    Create a new _Provider service (this is an IService so must be
+    hooked up to a parent or otherwise started).
+
+    If foolscap.connections.tor or txtorcon are not installed, then
+    Provider.get_tor_handler() will return None.  If tahoe.cfg wants
+    to start an onion service too, then this `create()` method will
+    throw a nice error (and startService will throw an ugly error).
+    """
+    if import_tor is None:
+        import_tor = _import_tor
+    if import_txtorcon is None:
+        import_txtorcon = _import_txtorcon
+    provider = _Provider(config, reactor, import_tor(), import_txtorcon())
+    provider.check_onion_config()
+    return provider
+
+
 def data_directory(private_dir):
     return os.path.join(private_dir, "tor-statedir")
 
@@ -217,14 +220,14 @@ def create_config(reactor, cli_config):
 
 @implementer(IAddressFamily)
 class _Provider(service.MultiService):
-    def __init__(self, config, reactor):
+    def __init__(self, config, reactor, tor, txtorcon):
         service.MultiService.__init__(self)
         self._config = config
         self._tor_launched = None
         self._onion_ehs = None
         self._onion_tor_control_proto = None
-        self._tor = _import_tor()
+        self._tor = tor
-        self._txtorcon = _import_txtorcon()
+        self._txtorcon = txtorcon
         self._reactor = reactor
 
     def _get_tor_config(self, *args, **kwargs):