--- a/.taskcluster.yml
+++ b/.taskcluster.yml
@@ -40,16 +40,17 @@
 #     push: {owner, pushlog_id, revision},
 #     repository: {url, project, level},
 #     input,
 #     parameters,
 #     taskId,      // targetted taskId
 #     taskGroupId, // targetted taskGroupId
 #     action: {name, title, description, taskGroupId, symbol, repo_scope, cb_name}
 #     ownTaskId:   // taskId of the task that will be created
+#     clientId:    // clientId that triggered this hook
 #   }
 
 version: 1
 tasks:
   # NOTE: support for actions in ci-admin requires that the `tasks` property be an array *before* JSON-e rendering
   # takes place.
   - $if: 'tasks_for in ["hg-push", "action", "cron"]'
     then:

--- a/taskcluster/taskgraph/test/python.ini
+++ b/taskcluster/taskgraph/test/python.ini
@@ -9,16 +9,17 @@ skip-if = python == 3
 [test_files_changed.py]
 [test_generator.py]
 [test_graph.py]
 [test_morph.py]
 [test_optimize.py]
 [test_parameters.py]
 [test_target_tasks.py]
 [test_taskgraph.py]
+[test_taskcluster_yml.py]
 [test_transforms_base.py]
 [test_transforms_job.py]
 [test_try_option_syntax.py]
 [test_util_attributes.py]
 [test_util_docker.py]
 [test_util_parameterization.py]
 [test_util_python_path.py]
 [test_util_runnable_jobs.py]

new file mode 100644
--- /dev/null
+++ b/taskcluster/taskgraph/test/test_taskcluster_yml.py
@@ -0,0 +1,118 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, unicode_literals
+
+import jsone
+import pprint
+import slugid
+import unittest
+
+from mozunit import main
+
+from taskgraph.util.yaml import load_yaml
+from taskgraph.util.time import current_json_time
+from taskgraph import GECKO
+
+
+class TestTaskclusterYml(unittest.TestCase):
+
+    taskcluster_yml = load_yaml(GECKO, ".taskcluster.yml")
+
+    def test_push(self):
+        context = {
+            "tasks_for": "hg-push",
+            "push": {
+                "revision": "e8d2d9aff5026ef1f1777b781b47fdcbdb9d8f20",
+                "owner": "dustin@mozilla.com",
+                "pushlog_id": 1556565286,
+                "pushdate": 112957,
+            },
+            "repository": {
+                "url": "https://hg.mozilla.org/mozilla-central",
+                "project": "mozilla-central",
+                "level": "3",
+            },
+            "ownTaskId": slugid.nice().encode("ascii"),
+        }
+        rendered = jsone.render(self.taskcluster_yml, context)
+        pprint.pprint(rendered)
+        self.assertEqual(
+            rendered["tasks"][0]["metadata"]["name"], "Gecko Decision Task"
+        )
+
+    def test_cron(self):
+        context = {
+            "tasks_for": "cron",
+            "repository": {
+                "url": "https://hg.mozilla.org/mozilla-central",
+                "project": "mozilla-central",
+                "level": 3,
+            },
+            "push": {
+                "revision": "e8aebe488b2f2e567940577de25013d00e818f7c",
+                "pushlog_id": -1,
+                "pushdate": 0,
+                "owner": "cron",
+            },
+            "cron": {
+                "task_id": "<cron task id>",
+                "job_name": "test",
+                "job_symbol": "T",
+                "quoted_args": "abc def",
+            },
+            "now": current_json_time(),
+            "ownTaskId": slugid.nice().encode("ascii"),
+        }
+        rendered = jsone.render(self.taskcluster_yml, context)
+        pprint.pprint(rendered)
+        self.assertEqual(
+            rendered["tasks"][0]["metadata"]["name"], "Decision Task for cron job test"
+        )
+
+    def test_action(self):
+        context = {
+            "tasks_for": "action",
+            "repository": {
+                "url": "https://hg.mozilla.org/mozilla-central",
+                "project": "mozilla-central",
+                "level": 3,
+            },
+            "push": {
+                "revision": "e8d2d9aff5026ef1f1777b781b47fdcbdb9d8f20",
+                "owner": "dustin@mozilla.com",
+                "pushlog_id": 1556565286,
+                "pushdate": 112957,
+            },
+            "action": {
+                "name": "test-action",
+                "title": "Test Action",
+                "description": "Just testing",
+                "taskGroupId": slugid.nice().encode("ascii"),
+                "symbol": "t",
+                "repo_scope": "assume:repo:hg.mozilla.org/try:action:generic",
+                "cb_name": "test_action",
+            },
+            "input": {},
+            "parameters": {},
+            "now": current_json_time(),
+            "taskId": slugid.nice().encode("ascii"),
+            "ownTaskId": slugid.nice().encode("ascii"),
+            "clientId": "testing/testing/testing",
+        }
+        rendered = jsone.render(self.taskcluster_yml, context)
+        pprint.pprint(rendered)
+        self.assertEqual(
+            rendered["tasks"][0]["metadata"]["name"], "Action: Test Action"
+        )
+
+    def test_unknown(self):
+        context = {"tasks_for": "bitkeeper-push"}
+        rendered = jsone.render(self.taskcluster_yml, context)
+        pprint.pprint(rendered)
+        self.assertEqual(rendered["tasks"], [])
+
+
+if __name__ == "__main__":
+    main()