mercurial: add a config knob to apply patches to the tip revision (#105)

Author: cgsheeh

libmozevent/mercurial.py

@@ -58,6 +58,10 @@ def __init__(self, config, cache_root):
         self.try_syntax = config.get("try_syntax")
         self.try_name = config.get("try_name", "try")
         self.default_revision = config.get("default_revision", "tip")
+
+        # Apply patches to the latest revision when `True`.
+        self.use_latest_revision = config.get("use_latest_revision", False)
+
         if self.try_mode == TryMode.syntax:
             assert self.try_syntax, "Missing try syntax"
         self._repo = None
@@ -124,6 +128,15 @@ def has_revision(self, revision):
         except hglib.error.CommandError:
             return False
 
+    def get_base_identifier(self, needed_stack: list[PhabricatorPatch]) -> str:
+        """Return the base identifier to apply patches against."""
+        if self.use_latest_revision:
+            # Use `tip` when `use_latest_revision` is `True`.
+            return "tip"
+
+        # Otherwise use the base/parent revision of first revision in the stack.
+        return needed_stack[0].base_revision
+
     def apply_build(self, build):
         """
         Apply a stack of patches to mercurial repo
@@ -147,8 +160,9 @@ def apply_build(self, build):
             logger.info("All the patches are already applied")
             return
 
+        hg_base = self.get_base_identifier(needed_stack)
+
         # When base revision is missing, update to default revision
-        hg_base = needed_stack[0].base_revision
         build.base_revision = hg_base
         build.missing_base_revision = not self.has_revision(hg_base)
         if build.missing_base_revision:

tests/test_mercurial.py

@@ -9,6 +9,7 @@
 import responses
 from conftest import MockBuild
 
+from libmozdata.phabricator import PhabricatorPatch
 from libmozevent.bus import MessageBus
 from libmozevent.mercurial import MercurialWorker, Repository
 
@@ -898,3 +899,21 @@ async def sleep(self, value):
         ("GET", "http://test.status/try"),
     ]
     assert sleep_history == [42, 42, 2]
+
+
+def test_get_base_identifier(mock_mc):
+    stack = [
+        PhabricatorPatch(1, "PHID-abc", "", "abc", None),
+        PhabricatorPatch(2, "PHID-def", "", "def", None),
+        PhabricatorPatch(3, "PHID-ghi", "", "ghi", None),
+    ]
+
+    assert (
+        mock_mc.get_base_identifier(stack) == "abc"
+    ), "The base commit of the stack should be returned."
+
+    mock_mc.use_latest_revision = True
+
+    assert (
+        mock_mc.get_base_identifier(stack) == "tip"
+    ), "`tip` commit should be used when `use_latest_revision` is `True`."