diff --git a/homeassistant/components/__init__.py b/homeassistant/components/__init__.py
index 38780ed9b28..7d025bac765 100644
--- a/homeassistant/components/__init__.py
+++ b/homeassistant/components/__init__.py
@@ -11,7 +11,6 @@ import itertools as it
 import logging
 
 import homeassistant.core as ha
-from homeassistant.helpers.entity import split_entity_id
 from homeassistant.helpers.service import extract_entity_ids
 from homeassistant.loader import get_component
 from homeassistant.const import (
@@ -35,7 +34,7 @@ def is_on(hass, entity_id=None):
         entity_ids = hass.states.entity_ids()
 
     for entity_id in entity_ids:
-        domain = split_entity_id(entity_id)[0]
+        domain = ha.split_entity_id(entity_id)[0]
 
         module = get_component(domain)
 
@@ -95,7 +94,7 @@ def setup(hass, config):
 
         # Group entity_ids by domain. groupby requires sorted data.
         by_domain = it.groupby(sorted(entity_ids),
-                               lambda item: split_entity_id(item)[0])
+                               lambda item: ha.split_entity_id(item)[0])
 
         for domain, ent_ids in by_domain:
             # We want to block for all calls and only return when all calls
diff --git a/homeassistant/components/group.py b/homeassistant/components/group.py
index 9e0c0f897e5..be998b48f23 100644
--- a/homeassistant/components/group.py
+++ b/homeassistant/components/group.py
@@ -14,8 +14,7 @@ from homeassistant.const import (
     ATTR_ENTITY_ID, CONF_ICON, CONF_NAME, STATE_CLOSED, STATE_HOME,
     STATE_NOT_HOME, STATE_OFF, STATE_ON, STATE_OPEN, STATE_LOCKED,
     STATE_UNLOCKED, STATE_UNKNOWN, ATTR_ASSUMED_STATE)
-from homeassistant.helpers.entity import (
-    Entity, generate_entity_id, split_entity_id)
+from homeassistant.helpers.entity import Entity, generate_entity_id
 from homeassistant.helpers.event import track_state_change
 import homeassistant.helpers.config_validation as cv
 
@@ -101,7 +100,7 @@ def expand_entity_ids(hass, entity_ids):
 
         try:
             # If entity_id points at a group, expand it
-            domain, _ = split_entity_id(entity_id)
+            domain, _ = ha.split_entity_id(entity_id)
 
             if domain == DOMAIN:
                 found_ids.extend(
diff --git a/homeassistant/components/http.py b/homeassistant/components/http.py
index 96a4d196272..38f7b66f97d 100644
--- a/homeassistant/components/http.py
+++ b/homeassistant/components/http.py
@@ -20,7 +20,7 @@ from homeassistant.const import (
     HTTP_HEADER_ACCESS_CONTROL_ALLOW_ORIGIN,
     HTTP_HEADER_ACCESS_CONTROL_ALLOW_HEADERS, ALLOWED_CORS_HEADERS,
     EVENT_HOMEASSISTANT_STOP, EVENT_HOMEASSISTANT_START)
-from homeassistant.helpers.entity import split_entity_id
+from homeassistant.core import split_entity_id
 import homeassistant.util.dt as dt_util
 import homeassistant.helpers.config_validation as cv
 
diff --git a/homeassistant/components/logbook.py b/homeassistant/components/logbook.py
index 6508318a907..5adf21e1f3a 100644
--- a/homeassistant/components/logbook.py
+++ b/homeassistant/components/logbook.py
@@ -18,10 +18,8 @@ from homeassistant.components.http import HomeAssistantView
 from homeassistant.const import (EVENT_HOMEASSISTANT_START,
                                  EVENT_HOMEASSISTANT_STOP, EVENT_STATE_CHANGED,
                                  STATE_NOT_HOME, STATE_OFF, STATE_ON)
-from homeassistant.core import DOMAIN as HA_DOMAIN
-from homeassistant.core import State
+from homeassistant.core import State, split_entity_id, DOMAIN as HA_DOMAIN
 from homeassistant.helpers import template
-from homeassistant.helpers.entity import split_entity_id
 
 DOMAIN = "logbook"
 DEPENDENCIES = ['recorder', 'frontend']
diff --git a/homeassistant/components/recorder/models.py b/homeassistant/components/recorder/models.py
index fdb5642562f..fe67476b11e 100644
--- a/homeassistant/components/recorder/models.py
+++ b/homeassistant/components/recorder/models.py
@@ -9,9 +9,8 @@ from sqlalchemy import (Boolean, Column, DateTime, ForeignKey, Index, Integer,
 from sqlalchemy.ext.declarative import declarative_base
 
 import homeassistant.util.dt as dt_util
-from homeassistant.core import Event, EventOrigin, State
+from homeassistant.core import Event, EventOrigin, State, split_entity_id
 from homeassistant.remote import JSONEncoder
-from homeassistant.helpers.entity import split_entity_id
 
 # SQLAlchemy Schema
 # pylint: disable=invalid-name
diff --git a/homeassistant/components/script.py b/homeassistant/components/script.py
index 5f1e63f5d00..b235c4d4eb7 100644
--- a/homeassistant/components/script.py
+++ b/homeassistant/components/script.py
@@ -14,7 +14,8 @@ import voluptuous as vol
 from homeassistant.const import (
     ATTR_ENTITY_ID, SERVICE_TURN_OFF, SERVICE_TURN_ON,
     SERVICE_TOGGLE, STATE_ON, CONF_ALIAS)
-from homeassistant.helpers.entity import ToggleEntity, split_entity_id
+from homeassistant.core import split_entity_id
+from homeassistant.helpers.entity import ToggleEntity
 from homeassistant.helpers.entity_component import EntityComponent
 import homeassistant.helpers.config_validation as cv
 
diff --git a/homeassistant/config.py b/homeassistant/config.py
index a614f139e2f..1d280b40b1a 100644
--- a/homeassistant/config.py
+++ b/homeassistant/config.py
@@ -14,11 +14,12 @@ from homeassistant.const import (
     CONF_TIME_ZONE, CONF_CUSTOMIZE, CONF_ELEVATION, CONF_UNIT_SYSTEM_METRIC,
     CONF_UNIT_SYSTEM_IMPERIAL, CONF_TEMPERATURE_UNIT, TEMP_CELSIUS,
     __version__)
+from homeassistant.core import valid_entity_id
 from homeassistant.exceptions import HomeAssistantError
 from homeassistant.util.yaml import load_yaml
 import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.unit_system import (IMPERIAL_SYSTEM, METRIC_SYSTEM)
-from homeassistant.helpers.entity import valid_entity_id, set_customize
+from homeassistant.helpers.entity import set_customize
 from homeassistant.util import dt as date_util, location as loc_util
 
 _LOGGER = logging.getLogger(__name__)
diff --git a/homeassistant/core.py b/homeassistant/core.py
index 107008216da..bd33cae792a 100644
--- a/homeassistant/core.py
+++ b/homeassistant/core.py
@@ -9,22 +9,17 @@ import enum
 import functools as ft
 import logging
 import os
+import re
 import signal
 import threading
 import time
 from types import MappingProxyType
 
 # pylint: disable=unused-import
-from typing import Optional, Any, Callable  # NOQA
+from typing import Optional, Any, Callable, List  # NOQA
 
 import voluptuous as vol
 
-from homeassistant.helpers.typing import UnitSystemType  # NOQA
-
-import homeassistant.util as util
-import homeassistant.util.dt as dt_util
-import homeassistant.util.location as location
-from homeassistant.config import get_default_config_dir
 from homeassistant.const import (
     ATTR_DOMAIN, ATTR_FRIENDLY_NAME, ATTR_NOW, ATTR_SERVICE,
     ATTR_SERVICE_CALL_ID, ATTR_SERVICE_DATA, EVENT_CALL_SERVICE,
@@ -34,10 +29,11 @@ from homeassistant.const import (
     SERVICE_HOMEASSISTANT_RESTART, SERVICE_HOMEASSISTANT_STOP, __version__)
 from homeassistant.exceptions import (
     HomeAssistantError, InvalidEntityFormatError)
-from homeassistant.helpers.entity import split_entity_id, valid_entity_id
-from homeassistant.helpers.unit_system import (
-    METRIC_SYSTEM,
-)
+from homeassistant.helpers.typing import UnitSystemType  # NOQA
+from homeassistant.helpers.unit_system import METRIC_SYSTEM
+import homeassistant.util as util
+import homeassistant.util.dt as dt_util
+import homeassistant.util.location as location
 
 DOMAIN = "homeassistant"
 
@@ -52,9 +48,22 @@ SERVICE_CALL_LIMIT = 10  # seconds
 # will be added for each component that polls devices.
 MIN_WORKER_THREAD = 2
 
+# Pattern for validating entity IDs (format: <domain>.<entity>)
+ENTITY_ID_PATTERN = re.compile(r"^(\w+)\.(\w+)$")
+
 _LOGGER = logging.getLogger(__name__)
 
 
+def split_entity_id(entity_id: str) -> List[str]:
+    """Split a state entity_id into domain, object_id."""
+    return entity_id.split(".", 1)
+
+
+def valid_entity_id(entity_id: str) -> bool:
+    """Test if an entity ID is a valid format."""
+    return ENTITY_ID_PATTERN.match(entity_id) is not None
+
+
 class CoreState(enum.Enum):
     """Represent the current state of Home Assistant."""
 
@@ -734,7 +743,7 @@ class Config(object):
         self.api = None
 
         # Directory that holds the configuration
-        self.config_dir = get_default_config_dir()
+        self.config_dir = None
 
     def distance(self: object, lat: float, lon: float) -> float:
         """Calculate distance from Home Assistant."""
@@ -743,6 +752,8 @@ class Config(object):
 
     def path(self, *path):
         """Generate path to the file within the config dir."""
+        if self.config_dir is None:
+            raise HomeAssistantError("config_dir is not set")
         return os.path.join(self.config_dir, *path)
 
     def as_dict(self):
diff --git a/homeassistant/helpers/config_validation.py b/homeassistant/helpers/config_validation.py
index a9b965930ae..2c4ed6795e9 100644
--- a/homeassistant/helpers/config_validation.py
+++ b/homeassistant/helpers/config_validation.py
@@ -12,7 +12,7 @@ from homeassistant.const import (
     CONF_ALIAS, CONF_ENTITY_ID, CONF_VALUE_TEMPLATE, WEEKDAYS,
     CONF_CONDITION, CONF_BELOW, CONF_ABOVE, SUN_EVENT_SUNSET,
     SUN_EVENT_SUNRISE, CONF_UNIT_SYSTEM_IMPERIAL, CONF_UNIT_SYSTEM_METRIC)
-from homeassistant.helpers.entity import valid_entity_id
+from homeassistant.core import valid_entity_id
 import homeassistant.util.dt as dt_util
 from homeassistant.util import slugify
 
diff --git a/homeassistant/helpers/entity.py b/homeassistant/helpers/entity.py
index 6e75e8ce59b..2ec64b3ea09 100644
--- a/homeassistant/helpers/entity.py
+++ b/homeassistant/helpers/entity.py
@@ -1,6 +1,5 @@
 """An abstract class for entities."""
 import logging
-import re
 
 from typing import Any, Optional, List, Dict
 
@@ -19,9 +18,6 @@ _OVERWRITE = {}  # type: Dict[str, Any]
 
 _LOGGER = logging.getLogger(__name__)
 
-# Pattern for validating entity IDs (format: <domain>.<entity>)
-ENTITY_ID_PATTERN = re.compile(r"^(\w+)\.(\w+)$")
-
 
 def generate_entity_id(entity_id_format: str, name: Optional[str],
                        current_ids: Optional[List[str]]=None,
@@ -45,16 +41,6 @@ def set_customize(customize: Dict[str, Any]) -> None:
     _OVERWRITE = {key.lower(): val for key, val in customize.items()}
 
 
-def split_entity_id(entity_id: str) -> List[str]:
-    """Split a state entity_id into domain, object_id."""
-    return entity_id.split(".", 1)
-
-
-def valid_entity_id(entity_id: str) -> bool:
-    """Test if an entity ID is a valid format."""
-    return ENTITY_ID_PATTERN.match(entity_id) is not None
-
-
 class Entity(object):
     """An abstract class for Home Assistant entities."""
 
diff --git a/tests/helpers/test_entity.py b/tests/helpers/test_entity.py
index a465c2f2c74..593e8b433c0 100644
--- a/tests/helpers/test_entity.py
+++ b/tests/helpers/test_entity.py
@@ -37,11 +37,6 @@ class TestHelpersEntity(unittest.TestCase):
         state = self.hass.states.get(self.entity.entity_id)
         self.assertTrue(state.attributes.get(ATTR_HIDDEN))
 
-    def test_split_entity_id(self):
-        """Test split_entity_id."""
-        self.assertEqual(['domain', 'object_id'],
-                         entity.split_entity_id('domain.object_id'))
-
     def test_generate_entity_id_requires_hass_or_ids(self):
         """Ensure we require at least hass or current ids."""
         fmt = 'test.{}'
diff --git a/tests/test_core.py b/tests/test_core.py
index 56a44964e79..ea9f96ab808 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -25,6 +25,15 @@ from tests.common import get_test_home_assistant
 PST = pytz.timezone('America/Los_Angeles')
 
 
+class TestMethods(unittest.TestCase):
+    """Test the Home Assistant helper methods."""
+
+    def test_split_entity_id(self):
+        """Test split_entity_id."""
+        self.assertEqual(['domain', 'object_id'],
+                         ha.split_entity_id('domain.object_id'))
+
+
 class TestHomeAssistant(unittest.TestCase):
     """Test the Home Assistant core classes."""
 
@@ -442,28 +451,19 @@ class TestConfig(unittest.TestCase):
     def setUp(self):     # pylint: disable=invalid-name
         """Setup things to be run when tests are started."""
         self.config = ha.Config()
-
-    def test_config_dir_set_correct(self):
-        """Test config dir set correct."""
-        data_dir = os.getenv('APPDATA') if os.name == "nt" \
-            else os.path.expanduser('~')
-        self.assertEqual(os.path.join(data_dir, ".homeassistant"),
-                         self.config.config_dir)
+        self.assertIsNone(self.config.config_dir)
 
     def test_path_with_file(self):
         """Test get_config_path method."""
-        data_dir = os.getenv('APPDATA') if os.name == "nt" \
-            else os.path.expanduser('~')
-        self.assertEqual(os.path.join(data_dir, ".homeassistant", "test.conf"),
+        self.config.config_dir = '/tmp/ha-config'
+        self.assertEqual("/tmp/ha-config/test.conf",
                          self.config.path("test.conf"))
 
     def test_path_with_dir_and_file(self):
         """Test get_config_path method."""
-        data_dir = os.getenv('APPDATA') if os.name == "nt" \
-            else os.path.expanduser('~')
-        self.assertEqual(
-            os.path.join(data_dir, ".homeassistant", "dir", "test.conf"),
-            self.config.path("dir", "test.conf"))
+        self.config.config_dir = '/tmp/ha-config'
+        self.assertEqual("/tmp/ha-config/dir/test.conf",
+                         self.config.path("dir", "test.conf"))
 
     def test_as_dict(self):
         """Test as dict."""
diff --git a/tests/test_remote.py b/tests/test_remote.py
index 873fa423568..7c87bc4af33 100644
--- a/tests/test_remote.py
+++ b/tests/test_remote.py
@@ -10,7 +10,8 @@ import homeassistant.components.http as http
 from homeassistant.const import HTTP_HEADER_HA_AUTH, EVENT_STATE_CHANGED
 import homeassistant.util.dt as dt_util
 
-from tests.common import get_test_instance_port, get_test_home_assistant
+from tests.common import (
+    get_test_instance_port, get_test_home_assistant, get_test_config_dir)
 
 API_PASSWORD = "test1234"
 MASTER_PORT = get_test_instance_port()
@@ -52,6 +53,7 @@ def setUpModule():   # pylint: disable=invalid-name
 
     # Start slave
     slave = remote.HomeAssistant(master_api)
+    slave.config.config_dir = get_test_config_dir()
     bootstrap.setup_component(
         slave, http.DOMAIN,
         {http.DOMAIN: {http.CONF_API_PASSWORD: API_PASSWORD,