Raise a 'PushNotFound' when specified revision/branch does not exist

mozci/errors.py

@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+
+
+class BasePushException(Exception):
+    def __init__(self, rev, branch, msg):
+        self.rev = rev
+        self.branch = branch
+        self.msg = f"Error processing push '{rev}' on {branch}: {msg}"
+
+
+class PushNotFound(BasePushException):
+    """Raised when the requested push does not exist."""
+
+    def __init__(self, *args, **kwargs):
+        kwargs["msg"] = "does not exist!"
+        super(PushNotFound, self).__init__(*args, **kwargs)

mozci/util/hgmo.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 from adr.util.memoize import memoize
 
+from mozci.errors import PushNotFound
 from mozci.util.req import get_session
 
 
@@ -35,6 +36,10 @@ def create(rev, branch="autoland"):
     @memoize
     def _get_resource(self, url):
         r = get_session("hgmo").get(url)
+
+        if r.status_code == 404:
+            raise PushNotFound(**self.context)
+
         r.raise_for_status()
         return r.json()
 

tests/test_push.py

@@ -2,6 +2,7 @@
 
 import pytest
 
+from mozci.errors import PushNotFound
 from mozci.push import MAX_DEPTH, Push
 from mozci.task import Task
 from mozci.util.hgmo import HGMO
@@ -624,3 +625,29 @@ def test_create_push(responses):
     assert p2.rev == "123456"
     assert p2.id == 123
     assert p2.date == 1213174092
+
+
+def test_push_does_not_exist(responses):
+    # We hit hgmo when 'rev' is less than 40 characters.
+    rev = "foobar"
+    responses.add(
+        responses.GET,
+        HGMO.JSON_TEMPLATE.format(branch="integration/autoland", rev=rev),
+        json={f"error": "unknown revision '{rev}'"},
+        status=404,
+    )
+
+    with pytest.raises(PushNotFound):
+        Push(rev)
+
+    # Otherwise we need to hit hgmo some other way.
+    rev = "a" * 40
+    responses.add(
+        responses.GET,
+        HGMO.JSON_TEMPLATE.format(branch="integration/autoland", rev=rev),
+        json={f"error": "unknown revision '{rev}'"},
+        status=404,
+    )
+    p = Push(rev)
+    with pytest.raises(PushNotFound):
+        p.id