Add unit tests for get volume function

tests/data/volume.xml

@@ -0,0 +1,9 @@
+<?xml version="1.0"?>
+<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"
+            s:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
+    <s:Body>
+        <u:GetVolumeResponse xmlns:u="urn:schemas-upnp-org:service:RenderingControl:1">
+            <CurrentVolume>64</CurrentVolume>
+        </u:GetVolumeResponse>
+    </s:Body>
+</s:Envelope>

tests/device_test.py

@@ -48,6 +48,7 @@
 BASE_URL = 'http://test/sony'
 AV_TRANSPORT_URL = 'http://test:52323/upnp/control/AVTransport'
 AV_TRANSPORT_URL_NO_MEDIA = 'http://test2:52323/upnp/control/AVTransport'
+RENDERING_CONTROL_URL = 'http://test:52323/upnp/control/RenderingControl'
 REQUESTS_ERROR = 'http://ERROR'
 
 ACTION_LIST = [
@@ -168,6 +169,12 @@ def mocked_requests_post(*args, **kwargs):
                             read_file(
                                 'data/playing_status_legacy_no_media.xml'))
 
+    elif url == RENDERING_CONTROL_URL:
+        return MockResponse(None,
+                            200,
+                            read_file(
+                                'data/volume.xml'))
+
     elif url == COMMAND_LIST_V4:
         json_data = jsonpickle.decode(read_file('data/commandList.json'))
         return MockResponse(json_data, 200, "")
@@ -849,6 +856,14 @@ def test_playing_status_no_media_legacy(self, mocked_requests_post):
         device.av_transport_url = AV_TRANSPORT_URL
         self.assertEqual("PLAYING", device.get_playing_status())
 
+    @mock.patch('requests.post', side_effect=mocked_requests_post)
+    def test_volume(self, mocked_requests_post):
+        device = self.create_device()
+        self.assertEqual(-1, device.get_volume())
+
+        device.rendering_control_url = RENDERING_CONTROL_URL
+        self.assertEqual(64, device.get_volume())
+
     def test_irrc_is_dmr(self):
         dev = SonyDevice(host="none", nickname="none", ircc_port=42, dmr_port=42)
         self.assertEqual(dev.dmr_url, dev.ircc_url)