[stacked-changes] Prepare squashed commit

Bug: b/265929888
Change-Id: Ia492666a5707996d94a4b6f7668ceaeb0eda8c39
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4182841
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Commit-Queue: Joanna Wang <jojwang@chromium.org>
Reviewed-by: Gavin Mak <gavinmak@google.com>

git_cl.py

@@ -1576,6 +1576,38 @@ class Changelist(object):
       return title
     return user_title or title
 
+  def PrepareSquashedCommit(self, options, parent=None, end_commit=None):
+    # type: (optparse.Values, Optional[str], Optional[str]) -> _NewUpload()
+    """Create a squashed commit to upload."""
+    if parent is None:
+      origin, upstream_branch_ref = self.FetchUpstreamTuple(self.GetBranch())
+      upstream_branch = scm.GIT.ShortBranchName(upstream_branch_ref)
+      if origin == '.':
+        # upstream is another local branch.
+        # Assume we want to upload from upstream's last upload.
+        parent = scm.GIT.GetBranchConfig(settings.GetRoot(), upstream_branch,
+                                         GERRIT_SQUASH_HASH_CONFIG_KEY)
+        assert parent, ('upstream branch %s not configured correctly. '
+                        'Could not fetch latest gerrit upload from git '
+                        'config.')
+      else:
+        # upstream is the root of the tree.
+        parent = self.GetCommonAncestorWithUpstream()
+
+    if end_commit is None:
+      end_commit = RunGit(['rev-parse', self.branchref]).strip()
+
+    reviewers, ccs, change_desc = self._PrepareChange(options, parent,
+                                                      end_commit)
+    latest_tree = RunGit(['rev-parse', end_commit + ':']).strip()
+    with gclient_utils.temporary_file() as desc_tempfile:
+      gclient_utils.FileWrite(desc_tempfile, change_desc.description)
+      commit_to_push = RunGit(
+          ['commit-tree', latest_tree, '-p', parent, '-F',
+           desc_tempfile]).strip()
+
+    return _NewUpload(reviewers, ccs, commit_to_push, end_commit, change_desc)
+
   def PrepareCherryPickSquashedCommit(self, options):
     # type: (optparse.Values) -> _NewUpload()
     """Create a commit cherry-picked on parent to push."""

tests/git_cl_test.py

@@ -3559,6 +3559,66 @@ class ChangelistTest(unittest.TestCase):
     for user_title in ['not empty', 'yes', 'YES']:
       self.assertEqual(cl._GetTitleForUpload(options), user_title)
 
+  @mock.patch('git_cl.Settings.GetRoot', return_value='')
+  @mock.patch('git_cl.RunGit')
+  @mock.patch('git_cl.Changelist._PrepareChange')
+  @mock.patch('git_cl.Changelist.GetCommonAncestorWithUpstream')
+  @mock.patch('git_cl.Changelist.FetchUpstreamTuple')
+  def testPrepareSquashedCommit(self, mockFetchUpstreamTuple,
+                                mockGetCommonAncestorWithUpstream,
+                                mockPrepareChange, mockRunGit, *_mocks):
+
+    change_desc = git_cl.ChangeDescription('BOO!')
+    reviewers = []
+    ccs = []
+    mockPrepareChange.return_value = (reviewers, ccs, change_desc)
+
+    parent_hash = 'upstream-gerrit-hash'
+    parent_hash_root = 'root-commit'
+    hash_to_push = 'new-squash-hash'
+    hash_to_push_root = 'new-squash-hash-root'
+    branchref = 'refs/heads/current-branch'
+    end_hash = 'end-hash'
+    tree_hash = 'tree-hash'
+
+    def mock_run_git(commands):
+      if {'commit-tree', tree_hash, '-p', parent_hash,
+          '-F'}.issubset(set(commands)):
+        return hash_to_push
+      if {'commit-tree', tree_hash, '-p', parent_hash_root,
+          '-F'}.issubset(set(commands)):
+        return hash_to_push_root
+      if commands == ['rev-parse', branchref]:
+        return end_hash
+      if commands == ['rev-parse', end_hash + ':']:
+        return tree_hash
+
+    mockRunGit.side_effect = mock_run_git
+    cl = git_cl.Changelist(branchref=branchref)
+    options = optparse.Values()
+
+    # local origin
+    mockFetchUpstreamTuple.return_value = ('.', 'refs/heads/upstreamA')
+    self.mockGit.config['branch.upstreamA.%s' %
+                        git_cl.GERRIT_SQUASH_HASH_CONFIG_KEY] = (parent_hash)
+
+    new_upload = cl.PrepareSquashedCommit(options)
+    self.assertEqual(new_upload.reviewers, reviewers)
+    self.assertEqual(new_upload.ccs, ccs)
+    self.assertEqual(new_upload.commit_to_push, hash_to_push)
+    self.assertEqual(new_upload.new_last_uploaded_commit, end_hash)
+    self.assertEqual(new_upload.change_desc, change_desc)
+    mockPrepareChange.assert_called_with(options, parent_hash, end_hash)
+
+    # remote origin
+    mockFetchUpstreamTuple.return_value = ('origin', 'refs/heads/release-1')
+    mockGetCommonAncestorWithUpstream.return_value = parent_hash_root
+
+    new_upload = cl.PrepareSquashedCommit(options)
+    self.assertEqual(new_upload.commit_to_push, hash_to_push_root)
+    self.assertEqual(new_upload.new_last_uploaded_commit, end_hash)
+    mockPrepareChange.assert_called_with(options, parent_hash_root, end_hash)
+
   @mock.patch('git_cl.Settings.GetRoot', return_value='')
   @mock.patch('git_cl.Changelist.FetchUpstreamTuple')
   @mock.patch('git_cl.RunGitWithCode')