diff --git a/homeassistant/components/sun.py b/homeassistant/components/sun.py
index f9f10840928..5ab4d6f598b 100644
--- a/homeassistant/components/sun.py
+++ b/homeassistant/components/sun.py
@@ -28,8 +28,10 @@ def is_on(hass, entity_id=None):
     return hass.states.is_state(entity_id, STATE_ABOVE_HORIZON)
 
 
-def next_setting(hass):
+def next_setting(hass, entity_id=None):
     """ Returns the datetime object representing the next sun setting. """
+    entity_id = entity_id or ENTITY_ID
+
     state = hass.states.get(ENTITY_ID)
 
     try:
@@ -40,8 +42,10 @@ def next_setting(hass):
         return None
 
 
-def next_rising(hass):
+def next_rising(hass, entity_id=None):
     """ Returns the datetime object representing the next sun rising. """
+    entity_id = entity_id or ENTITY_ID
+
     state = hass.states.get(ENTITY_ID)
 
     try:
@@ -73,6 +77,25 @@ def setup(hass, config):
     latitude = config[ha.DOMAIN][ha.CONF_LATITUDE]
     longitude = config[ha.DOMAIN][ha.CONF_LONGITUDE]
 
+    # Validate latitude and longitude
+    observer = ephem.Observer()
+
+    errors = []
+
+    try:
+        observer.lat = latitude  # pylint: disable=assigning-non-slot
+    except ValueError:
+        errors.append("invalid value for latitude given: {}".format(latitude))
+
+    try:
+        observer.long = longitude  # pylint: disable=assigning-non-slot
+    except ValueError:
+        errors.append("invalid value for latitude given: {}".format(latitude))
+
+    if errors:
+        logger.error("Error setting up: %s", ", ".join(errors))
+        return False
+
     def update_sun_state(now):    # pylint: disable=unused-argument
         """ Method to update the current state of the sun and
             set time of next setting and rising. """
diff --git a/homeassistant/util.py b/homeassistant/util.py
index b4c7966baa3..67188926546 100644
--- a/homeassistant/util.py
+++ b/homeassistant/util.py
@@ -188,6 +188,8 @@ def validate_config(config, items, logger):
     """
     errors_found = False
     for domain in items.keys():
+        config.setdefault(domain, {})
+
         errors = [item for item in items[domain] if item not in config[domain]]
 
         if errors:
diff --git a/test/test_component_sun.py b/test/test_component_sun.py
new file mode 100644
index 00000000000..d310b59cb8e
--- /dev/null
+++ b/test/test_component_sun.py
@@ -0,0 +1,98 @@
+"""
+test.test_component_chromecast
+~~~~~~~~~~~
+
+Tests Chromecast component.
+"""
+# pylint: disable=too-many-public-methods,protected-access
+import logging
+import unittest
+import datetime as dt
+
+import ephem
+
+import homeassistant as ha
+import homeassistant.components as components
+import homeassistant.components.sun as sun
+
+
+class TestSun(unittest.TestCase):
+    """ Test the sun module. """
+
+    def setUp(self):  # pylint: disable=invalid-name
+        self.hass = ha.HomeAssistant()
+
+    def tearDown(self):  # pylint: disable=invalid-name
+        """ Stop down stuff we started. """
+        self.hass._pool.stop()
+
+    def test_is_on(self):
+        """ Test is_on method. """
+        self.hass.states.set(sun.ENTITY_ID, sun.STATE_ABOVE_HORIZON)
+        self.assertTrue(sun.is_on(self.hass))
+        self.hass.states.set(sun.ENTITY_ID, sun.STATE_BELOW_HORIZON)
+        self.assertFalse(sun.is_on(self.hass))
+
+    def test_setting_rising(self):
+        """ Test retrieving sun setting and rising. """
+        # Compare it with the real data
+        self.assertTrue(sun.setup(
+            self.hass,
+            {ha.DOMAIN: {
+                ha.CONF_LATITUDE: '32.87336',
+                ha.CONF_LONGITUDE: '117.22743'
+            }}))
+
+        observer = ephem.Observer()
+        observer.lat = '32.87336'  # pylint: disable=assigning-non-slot
+        observer.long = '117.22743'  # pylint: disable=assigning-non-slot
+
+        body_sun = ephem.Sun()  # pylint: disable=no-member
+        next_rising_dt = ephem.localtime(observer.next_rising(body_sun))
+        next_setting_dt = ephem.localtime(observer.next_setting(body_sun))
+
+        # Home Assistant strips out microseconds
+        # strip it out of the datetime objects
+        next_rising_dt = next_rising_dt - dt.timedelta(
+            microseconds=next_rising_dt.microsecond)
+        next_setting_dt = next_setting_dt - dt.timedelta(
+            microseconds=next_setting_dt.microsecond)
+
+        self.assertEqual(next_rising_dt, sun.next_rising(self.hass))
+        self.assertEqual(next_setting_dt, sun.next_setting(self.hass))
+
+        # Point it at a state without the proper attributes
+        self.hass.states.set(sun.ENTITY_ID, sun.STATE_ABOVE_HORIZON)
+        self.assertIsNone(sun.next_rising(self.hass))
+        self.assertIsNone(sun.next_setting(self.hass))
+
+        # Point it at a non-existing state
+        self.assertIsNone(sun.next_rising(self.hass, 'non.existing'))
+        self.assertIsNone(sun.next_setting(self.hass, 'non.existing'))
+
+    def test_setup(self):
+        """ Test Sun setup with empty and wrong configs. """
+        self.assertFalse(sun.setup(self.hass, {}))
+        self.assertFalse(sun.setup(self.hass, {sun.DOMAIN: {}}))
+        self.assertFalse(sun.setup(
+            self.hass, {ha.DOMAIN: {ha.CONF_LATITUDE: '32.87336'}}))
+        self.assertFalse(sun.setup(
+            self.hass, {ha.DOMAIN: {ha.CONF_LONGITUDE: '117.22743'}}))
+        self.assertFalse(sun.setup(
+            self.hass, {ha.DOMAIN: {ha.CONF_LATITUDE: 'hello'}}))
+        self.assertFalse(sun.setup(
+            self.hass, {ha.DOMAIN: {ha.CONF_LONGITUDE: 'how are you'}}))
+        self.assertFalse(sun.setup(
+            self.hass, {ha.DOMAIN: {
+                ha.CONF_LATITUDE: 'wrong', ha.CONF_LONGITUDE: '117.22743'
+            }}))
+        self.assertFalse(sun.setup(
+            self.hass, {ha.DOMAIN: {
+                ha.CONF_LATITUDE: '32.87336', ha.CONF_LONGITUDE: 'wrong'
+            }}))
+
+        # Test with correct config
+        self.assertTrue(sun.setup(
+            self.hass, {ha.DOMAIN: {
+                ha.CONF_LATITUDE: '32.87336', ha.CONF_LONGITUDE: '117.22743'
+            }}))