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diff --git a/synapse/server.py b/synapse/server.py
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+++ b/synapse/server.py
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+# -*- coding: utf-8 -*-
+# Copyright 2014 matrix.org
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# This file provides some classes for setting up (partially-populated)
+# homeservers; either as a full homeserver as a real application, or a small
+# partial one for unit test mocking.
+
+# Imports required for the default HomeServer() implementation
+from synapse.federation import initialize_http_replication
+from synapse.federation.handler import FederationEventHandler
+from synapse.api.events.factory import EventFactory
+from synapse.api.notifier import Notifier
+from synapse.api.auth import Auth
+from synapse.handlers import Handlers
+from synapse.rest import RestServletFactory
+from synapse.state import StateHandler
+from synapse.storage import DataStore
+from synapse.types import UserID
+from synapse.util import Clock
+from synapse.util.distributor import Distributor
+from synapse.util.lockutils import LockManager
+
+
+class BaseHomeServer(object):
+    """A basic homeserver object without lazy component builders.
+
+    This will need all of the components it requires to either be passed as
+    constructor arguments, or the relevant methods overriding to create them.
+    Typically this would only be used for unit tests.
+
+    For every dependency in the DEPENDENCIES list below, this class creates one
+    method,
+        def get_DEPENDENCY(self)
+    which returns the value of that dependency. If no value has yet been set
+    nor was provided to the constructor, it will attempt to call a lazy builder
+    method called
+        def build_DEPENDENCY(self)
+    which must be implemented by the subclass. This code may call any of the
+    required "get" methods on the instance to obtain the sub-dependencies that
+    one requires.
+    """
+
+    DEPENDENCIES = [
+        'clock',
+        'http_server',
+        'http_client',
+        'db_pool',
+        'persistence_service',
+        'federation',
+        'replication_layer',
+        'datastore',
+        'event_factory',
+        'handlers',
+        'auth',
+        'rest_servlet_factory',
+        'state_handler',
+        'room_lock_manager',
+        'notifier',
+        'distributor',
+    ]
+
+    def __init__(self, hostname, **kwargs):
+        """
+        Args:
+            hostname : The hostname for the server.
+        """
+        self.hostname = hostname
+        self._building = {}
+
+        # Other kwargs are explicit dependencies
+        for depname in kwargs:
+            setattr(self, depname, kwargs[depname])
+
+    @classmethod
+    def _make_dependency_method(cls, depname):
+        def _get(self):
+            if hasattr(self, depname):
+                return getattr(self, depname)
+
+            if hasattr(self, "build_%s" % (depname)):
+                # Prevent cyclic dependencies from deadlocking
+                if depname in self._building:
+                    raise ValueError("Cyclic dependency while building %s" % (
+                        depname,
+                    ))
+                self._building[depname] = 1
+
+                builder = getattr(self, "build_%s" % (depname))
+                dep = builder()
+                setattr(self, depname, dep)
+
+                del self._building[depname]
+
+                return dep
+
+            raise NotImplementedError(
+                "%s has no %s nor a builder for it" % (
+                    type(self).__name__, depname,
+                )
+            )
+
+        setattr(BaseHomeServer, "get_%s" % (depname), _get)
+
+    # Other utility methods
+    def parse_userid(self, s):
+        """Parse the string given by 's' as a User ID and return a UserID
+        object."""
+        return UserID.from_string(s, hs=self)
+
+# Build magic accessors for every dependency
+for depname in BaseHomeServer.DEPENDENCIES:
+    BaseHomeServer._make_dependency_method(depname)
+
+
+class HomeServer(BaseHomeServer):
+    """A homeserver object that will construct most of its dependencies as
+    required.
+
+    It still requires the following to be specified by the caller:
+        http_server
+        http_client
+        db_pool
+    """
+
+    def build_clock(self):
+        return Clock()
+
+    def build_replication_layer(self):
+        return initialize_http_replication(self)
+
+    def build_federation(self):
+        return FederationEventHandler(self)
+
+    def build_datastore(self):
+        return DataStore(self)
+
+    def build_event_factory(self):
+        return EventFactory()
+
+    def build_handlers(self):
+        return Handlers(self)
+
+    def build_notifier(self):
+        return Notifier(self)
+
+    def build_auth(self):
+        return Auth(self)
+
+    def build_rest_servlet_factory(self):
+        return RestServletFactory(self)
+
+    def build_state_handler(self):
+        return StateHandler(self)
+
+    def build_room_lock_manager(self):
+        return LockManager()
+
+    def build_distributor(self):
+        return Distributor()
+
+    def register_servlets(self):
+        """Simply building the ServletFactory is sufficient to have it
+        register."""
+        self.get_rest_servlet_factory()