Add test case for cmysql unknown

Author: tammy-baylis-swi

tests/opentelemetry-docker-tests/tests/mysql/test_mysql_sqlcommenter.py

@@ -79,3 +79,43 @@ def test_commenter_enabled_connection_proxy(self):
         cursor.close()
         MySQLInstrumentor().uninstrument_connection(instrumented_cnx)
         cnx.close()
+
+    def test_commenter_enabled_unknown_mysql_client_version(self):
+        MySQLInstrumentor().instrument(enable_commenter=True)
+        cnx = mysql.connector.connect(
+            user=MYSQL_USER,
+            password=MYSQL_PASSWORD,
+            host=MYSQL_HOST,
+            port=MYSQL_PORT,
+            database=MYSQL_DB_NAME,
+        )
+        cursor = cnx.cursor()
+
+        # Temporarily remove _cmysql
+        original_cmysql = None
+        try:
+            if hasattr(cursor._cnx, "_cmysql"):
+                original_cmysql = cursor._cnx._cmysql
+                delattr(cursor._cnx, "_cmysql")
+        except AttributeError:
+            pass
+
+        cursor.execute("SELECT 1;")
+        cursor.fetchall()
+
+        self.assertRegex(
+            cursor.statement,
+            r"SELECT 1 /\*db_driver='mysql\.connector[^']*',dbapi_level='\d\.\d',dbapi_threadsafety=\d,driver_paramstyle='[^']*',mysql_client_version='unknown',traceparent='[^']*'\*/;",
+        )
+        self.assertIn("mysql_client_version='unknown'", cursor.statement)
+
+        # Restore _cmysql
+        if original_cmysql is not None:
+            try:
+                cursor._cnx._cmysql = original_cmysql
+            except AttributeError:
+                pass
+
+        cursor.close()
+        cnx.close()
+        MySQLInstrumentor().uninstrument()