feat: set a separate user agent for the DB API (#566)

* feat: set a separate user agent for the DB API

* fix test error

* fix the test

google/cloud/spanner_dbapi/version.py

@@ -12,8 +12,9 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+import pkg_resources
 import platform
 
 PY_VERSION = platform.python_version()
-VERSION = "2.2.0a1"
-DEFAULT_USER_AGENT = "django_spanner/" + VERSION
+VERSION = pkg_resources.get_distribution("google-cloud-spanner").version
+DEFAULT_USER_AGENT = "dbapi/" + VERSION

tests/system/test_dbapi.py

@@ -14,11 +14,12 @@
 
 import hashlib
 import pickle
+import pkg_resources
 
 import pytest
 
 from google.cloud import spanner_v1
-from google.cloud.spanner_dbapi.connection import Connection
+from google.cloud.spanner_dbapi.connection import connect, Connection
 from . import _helpers
 
 DATABASE_NAME = "dbapi-txn"
@@ -357,3 +358,12 @@ def test_ping(shared_instance, dbapi_database):
     conn = Connection(shared_instance, dbapi_database)
     conn.validate()
     conn.close()
+
+
+def test_user_agent(shared_instance, dbapi_database):
+    """Check that DB API uses an appropriate user agent."""
+    conn = connect(shared_instance.name, dbapi_database.name)
+    assert (
+        conn.instance._client._client_info.user_agent
+        == "dbapi/" + pkg_resources.get_distribution("google-cloud-spanner").version
+    )