Add test to check CfgNotFound exception (#469)

* Remove Exception warning if option is set to True too

* Assess Exception not raised

* Second warning is covered anyway

datadog/util/hostname.py

@@ -50,7 +50,7 @@ def get_hostname(hostname_from_config):
     hostname = None
     config = None
 
-    # first, try the config
+    # first, try the config if hostname_from_config is set to True
     try:
         if hostname_from_config:
             config = get_config()

tests/unit/api/test_api.py

@@ -40,6 +40,8 @@
     HOST_NAME,
     FAKE_PROXY
 )
+from datadog.util.hostname import CfgNotFound, get_hostname
+
 from tests.util.contextmanagers import EnvVars
 
 
@@ -117,9 +119,15 @@ def test_get_hostname(self, mock_config_path):
         initialize()
         self.assertEqual(api._host_name, HOST_NAME, api._host_name)
 
+    def test_hostname_warning_not_present(self):
+        try:
+            get_hostname(hostname_from_config=False)
+        except CfgNotFound:
+            pytest.fail("Unexpected CfgNotFound Exception")
+
     def test_errors_suppressed(self):
         """
-        API `errors` field ApiError supppressed when specified
+        API `errors` field ApiError suppressed when specified
         """
         # Test API, application keys, API host, and some HTTP client options
         initialize(api_key=API_KEY, app_key=APP_KEY, api_host=API_HOST)