Core add user agent

sdk/core/azure-core/azure/core/pipeline/policies/_universal.py

@@ -181,6 +181,7 @@ def __init__(self, base_user_agent=None, **kwargs):  # pylint: disable=super-ini
         # type: (Optional[str], bool) -> None
         self.overwrite = kwargs.pop('user_agent_overwrite', False)
         self.use_env = kwargs.pop('user_agent_use_env', True)
+        application_id = kwargs.pop('user_agent', None)
 
         if base_user_agent is None:
             self._user_agent = "azsdk-python-core/{} Python/{} ({})".format(
@@ -191,6 +192,9 @@ def __init__(self, base_user_agent=None, **kwargs):  # pylint: disable=super-ini
         else:
             self._user_agent = base_user_agent
 
+        if application_id:
+            self._user_agent = "{} {}".format(application_id, self._user_agent)
+
     @property
     def user_agent(self):
         # type: () -> str
@@ -222,7 +226,7 @@ def on_request(self, request):
             if options_dict.pop('user_agent_overwrite', self.overwrite):
                 http_request.headers[self._USERAGENT] = user_agent
             else:
-                user_agent = "{} {}".format(self.user_agent, user_agent)
+                user_agent = "{} {}".format(user_agent, self.user_agent)
                 http_request.headers[self._USERAGENT] = user_agent
 
         elif self.overwrite or self._USERAGENT not in http_request.headers:

sdk/core/azure-core/tests/test_user_agent_policy.py

@@ -0,0 +1,22 @@
+# ------------------------------------
+# Copyright (c) Microsoft Corporation.
+# Licensed under the MIT License.
+# ------------------------------------
+"""Tests for the user agent policy."""
+from azure.core.pipeline.policies import UserAgentPolicy
+from azure.core.pipeline.transport import HttpRequest
+from azure.core.pipeline import PipelineRequest, PipelineContext
+
+def test_user_agent_policy():
+    user_agent = UserAgentPolicy(base_user_agent='foo')
+    assert user_agent._user_agent == 'foo'
+
+    user_agent = UserAgentPolicy(base_user_agent='foo', user_agent='bar')
+    assert user_agent._user_agent == 'bar foo'
+
+    request = HttpRequest('GET', 'http://127.0.0.1/')
+    pipeline_request = PipelineRequest(request, PipelineContext(None))
+
+    pipeline_request.context.options['user_agent'] = 'xyz'
+    user_agent.on_request(pipeline_request)
+    assert request.headers['User-Agent'] == 'xyz bar foo'