[py] Honor cmd line args passed to Service ctor (#4167)

* [py] Honor cmd line args passed to Service ctor

Ensure that when command line arguments are specified during creation of
a Service object for GeckoDriver, these arguments are used in the
resulting invocation of the binary.

Author: jugglinmike

py/selenium/webdriver/firefox/service.py

@@ -48,7 +48,7 @@ def __init__(self, executable_path, port=0, service_args=None,
         self.service_args = service_args or []
 
     def command_line_args(self):
-        return ["--port", "%d" % self.port]
+        return ["--port", "%d" % self.port] + self.service_args
 
     def send_remote_shutdown_command(self):
         pass

py/test/selenium/webdriver/marionette/mn_service_tests.py

@@ -0,0 +1,31 @@
+# Licensed to the Software Freedom Conservancy (SFC) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The SFC licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+from selenium.webdriver.firefox.service import Service
+
+def test_command_line_args():
+    service = Service("geckodriver", service_args=["--log", "trace"])
+    found = False
+
+    args = service.command_line_args()
+
+    for idx in range(len(args) - 1):
+        if args[idx] == "--log" and args[idx + 1] == "trace":
+            found = True
+            break
+
+    assert found, "Provided arguments do not exist in array"