Improve test coverage of error conditions.

tests/components/sensor/test_template.py

@@ -4,9 +4,6 @@ tests.components.sensor.template
 
 Tests template sensor.
 """
-from unittest.mock import patch
-
-import pytest
 
 import homeassistant.core as ha
 import homeassistant.components.sensor as sensor
@@ -56,8 +53,46 @@ class TestTemplateSensor:
             }
         })
 
-
         self.hass.states.set('sensor.test_state', 'Works')
         self.hass.pool.block_till_done()
         state = self.hass.states.get('sensor.test_template_sensor')
         assert state.state == 'error'
+
+    def test_invalid_name_does_not_create(self):
+        assert sensor.setup(self.hass, {
+            'sensor': {
+                'platform': 'template',
+                'sensors': {
+                    'test INVALID sensor': {
+                        'value_template':
+                            "{{ states.sensor.test_state.state }}"
+                    }
+                }
+            }
+        })
+        assert self.hass.states.all() == []
+
+    def test_invalid_config_does_not_create(self):
+        assert sensor.setup(self.hass, {
+            'sensor': {
+                'platform': 'template',
+                'sensors': {
+                    'test_template_sensor': {}
+                }
+            }
+        })
+        assert self.hass.states.all() == []
+
+    def test_missing_template_does_not_create(self):
+        assert sensor.setup(self.hass, {
+            'sensor': {
+                'platform': 'template',
+                'sensors': {
+                    'test_template_sensor': {
+                        'not_value_template':
+                            "{{ states.sensor.test_state.state }}"
+                    }
+                }
+            }
+        })
+        assert self.hass.states.all() == []