Migrate tests to pytest (#23544)

* Migrate tests to pytest

* Fixup

* Use loop fixture in test_check_config

* Lint

tests/helpers/test_temperature.py

@@ -1,50 +1,34 @@
 """Tests Home Assistant temperature helpers."""
-import unittest
-
-from tests.common import get_test_home_assistant
+import pytest
 
 from homeassistant.const import (
     TEMP_CELSIUS, PRECISION_WHOLE, TEMP_FAHRENHEIT, PRECISION_HALVES,
     PRECISION_TENTHS)
 from homeassistant.helpers.temperature import display_temp
-from homeassistant.util.unit_system import METRIC_SYSTEM
-import pytest
 
 TEMP = 24.636626
 
 
-class TestHelpersTemperature(unittest.TestCase):
-    """Set up the temperature tests."""
+def test_temperature_not_a_number(hass):
+    """Test that temperature is a number."""
+    temp = "Temperature"
+    with pytest.raises(Exception) as exception:
+        display_temp(hass, temp, TEMP_CELSIUS, PRECISION_HALVES)
 
-    def setUp(self):
-        """Set up the tests."""
-        self.hass = get_test_home_assistant()
-        self.hass.config.unit_system = METRIC_SYSTEM
+    assert "Temperature is not a number: {}".format(temp) \
+        in str(exception)
 
-    def tearDown(self):
-        """Stop down stuff we started."""
-        self.hass.stop()
 
-    def test_temperature_not_a_number(self):
-        """Test that temperature is a number."""
-        temp = "Temperature"
-        with pytest.raises(Exception) as exception:
-            display_temp(self.hass, temp, TEMP_CELSIUS, PRECISION_HALVES)
+def test_celsius_halves(hass):
+    """Test temperature to celsius rounding to halves."""
+    assert display_temp(hass, TEMP, TEMP_CELSIUS, PRECISION_HALVES) == 24.5
 
-        assert "Temperature is not a number: {}".format(temp) \
-            in str(exception)
 
-    def test_celsius_halves(self):
-        """Test temperature to celsius rounding to halves."""
-        assert 24.5 == display_temp(
-            self.hass, TEMP, TEMP_CELSIUS, PRECISION_HALVES)
+def test_celsius_tenths(hass):
+    """Test temperature to celsius rounding to tenths."""
+    assert display_temp(hass, TEMP, TEMP_CELSIUS, PRECISION_TENTHS) == 24.6
 
-    def test_celsius_tenths(self):
-        """Test temperature to celsius rounding to tenths."""
-        assert 24.6 == display_temp(
-            self.hass, TEMP, TEMP_CELSIUS, PRECISION_TENTHS)
 
-    def test_fahrenheit_wholes(self):
-        """Test temperature to fahrenheit rounding to wholes."""
-        assert -4 == display_temp(
-            self.hass, TEMP, TEMP_FAHRENHEIT, PRECISION_WHOLE)
+def test_fahrenheit_wholes(hass):
+    """Test temperature to fahrenheit rounding to wholes."""
+    assert display_temp(hass, TEMP, TEMP_FAHRENHEIT, PRECISION_WHOLE) == -4