Added unit test to the Yahoo Finance sensor (#3943)

tests/components/sensor/test_yahoo_finance.py

@@ -0,0 +1,41 @@
+"""The tests for the Yahoo Finance platform."""
+import json
+
+import unittest
+from unittest.mock import patch
+
+import homeassistant.components.sensor as sensor
+from homeassistant.bootstrap import setup_component
+from tests.common import (
+    get_test_home_assistant, load_fixture, assert_setup_component)
+
+VALID_CONFIG = {
+    'platform': 'yahoo_finance',
+    'symbol': 'YHOO'
+}
+
+
+class TestYahooFinanceSetup(unittest.TestCase):
+    """Test the Yahoo Finance platform."""
+
+    def setUp(self):
+        """Initialize values for this testcase class."""
+        self.hass = get_test_home_assistant()
+        self.config = VALID_CONFIG
+
+    def tearDown(self):
+        """Stop everything that was started."""
+        self.hass.stop()
+
+    @patch('yahoo_finance.Base._request',
+           return_value=json.loads(load_fixture('yahoo_finance.json')))
+    def test_default_setup(self, m):  # pylint: disable=invalid-name
+        """Test the default setup."""
+        with assert_setup_component(1, sensor.DOMAIN):
+            assert setup_component(self.hass, sensor.DOMAIN, {
+                'sensor': VALID_CONFIG})
+
+        state = self.hass.states.get('sensor.yahoo_stock')
+        self.assertEqual("41.69", state.attributes.get('open'))
+        self.assertEqual("41.79", state.attributes.get('prev_close'))
+        self.assertEqual("YHOO", state.attributes.get('unit_of_measurement'))