Adds template function state_attr to get attribute from a state (#13378)

* Adds template function state_attr to get attribute from a state
Refactored is_state_attr to use new function
Adds tests for state_attr

* Fixes line too long and test bug

* Fixes pylint error

* Fixes tests and D401 lint error

homeassistant/helpers/template.py

@@ -28,7 +28,7 @@ DATE_STR_FORMAT = "%Y-%m-%d %H:%M:%S"
 
 _RE_NONE_ENTITIES = re.compile(r"distance\(|closest\(", re.I | re.M)
 _RE_GET_ENTITIES = re.compile(
-    r"(?:(?:states\.|(?:is_state|is_state_attr|states)"
+    r"(?:(?:states\.|(?:is_state|is_state_attr|state_attr|states)"
     r"\((?:[\ \'\"]?))([\w]+\.[\w]+)|([\w]+))", re.I | re.M
 )
 
@@ -182,6 +182,7 @@ class Template(object):
             'distance': template_methods.distance,
             'is_state': self.hass.states.is_state,
             'is_state_attr': template_methods.is_state_attr,
+            'state_attr': template_methods.state_attr,
             'states': AllStates(self.hass),
         })
 
@@ -405,9 +406,15 @@ class TemplateMethods(object):
 
     def is_state_attr(self, entity_id, name, value):
         """Test if a state is a specific attribute."""
+        state_attr = self.state_attr(entity_id, name)
+        return state_attr is not None and state_attr == value
+
+    def state_attr(self, entity_id, name):
+        """Get a specific attribute from a state."""
         state_obj = self._hass.states.get(entity_id)
-        return state_obj is not None and \
-            state_obj.attributes.get(name) == value
+        if state_obj is not None:
+            return state_obj.attributes.get(name)
+        return None
 
     def _resolve_state(self, entity_id_or_state):
         """Return state or entity_id if given."""

tests/helpers/test_template.py

@@ -397,6 +397,19 @@ class TestHelpersTemplate(unittest.TestCase):
                 """, self.hass)
         self.assertEqual('False', tpl.render())
 
+    def test_state_attr(self):
+        """Test state_attr method."""
+        self.hass.states.set('test.object', 'available', {'mode': 'on'})
+        tpl = template.Template("""
+{% if state_attr("test.object", "mode") == "on" %}yes{% else %}no{% endif %}
+                """, self.hass)
+        self.assertEqual('yes', tpl.render())
+
+        tpl = template.Template("""
+{{ state_attr("test.noobject", "mode") == None }}
+                """, self.hass)
+        self.assertEqual('True', tpl.render())
+
     def test_states_function(self):
         """Test using states as a function."""
         self.hass.states.set('test.object', 'available')