Add a --dry-run option to git cl split

git cl split previously had no way to find out what it would do before
it went ahead and uploaded CLs. Now you can use --dry-run to get it
to print info about each CL it would upload.

Change-Id: If2ac74a89b0a8b30d86819e16ece46f487b1e7c7
Reviewed-on: https://chromium-review.googlesource.com/821336Reviewed-by: Aaron Gable <agable@chromium.org>
Commit-Queue: Chris Watkins <watk@chromium.org>

git_cl.py

@@ -5056,6 +5056,10 @@ def CMDsplit(parser, args):
                          "$directory will be replaced by each CL's directory.")
   parser.add_option("-c", "--comment", dest="comment_file",
                     help="A text file containing a CL comment.")
+  parser.add_option("-n", "--dry-run", dest="dry_run", action='store_true',
+                    default=False,
+                    help="List the files and reviewers for each CL that would "
+                         "be created, but don't create branches or CLs.")
   options, _ = parser.parse_args(args)
 
   if not options.description_file:
@@ -5065,7 +5069,7 @@ def CMDsplit(parser, args):
     return CMDupload(OptionParser(), args)
 
   return split_cl.SplitCl(options.description_file, options.comment_file,
-                          Changelist, WrappedCMDupload)
+                          Changelist, WrappedCMDupload, options.dry_run)
 
 
 @subcommand.usage('DEPRECATED')

split_cl.py

@@ -67,8 +67,7 @@ def AddUploadedByGitClSplitToDescription(description):
 
 
 def UploadCl(refactor_branch, refactor_branch_upstream, directory, files,
-             author, description, comment, owners_database, changelist,
-             cmd_upload):
+             description, comment, reviewers, changelist, cmd_upload):
   """Uploads a CL with all changes to |files| in |refactor_branch|.
 
   Args:
@@ -77,14 +76,12 @@ def UploadCl(refactor_branch, refactor_branch_upstream, directory, files,
     directory: Path to the directory that contains the OWNERS file for which
         to upload a CL.
     files: List of AffectedFile instances to include in the uploaded CL.
-    author: Email address of the user running this script.
     description: Description of the uploaded CL.
     comment: Comment to post on the uploaded CL.
-    owners_database: An owners.Database instance.
+    reviewers: A set of reviewers for the CL.
     changelist: The Changelist class.
     cmd_upload: The function associated with the git cl upload command.
   """
-
   # Create a branch.
   if not CreateBranchForDirectory(
       refactor_branch, directory, refactor_branch_upstream):
@@ -110,8 +107,6 @@ def UploadCl(refactor_branch, refactor_branch_upstream, directory, files,
     os.remove(tmp_file.name)
 
   # Upload a CL.
-  reviewers = owners_database.reviewers_for(
-      [f.LocalPath() for f in files], author)
   upload_args = ['-f', '--cq-dry-run', '-r', ','.join(reviewers)]
   if not comment:
     upload_args.append('--send-mail')
@@ -136,7 +131,32 @@ def GetFilesSplitByOwners(owners_database, files):
   return files_split_by_owners
 
 
-def SplitCl(description_file, comment_file, changelist, cmd_upload):
+def PrintClInfo(cl_index, num_cls, directory, file_paths, description,
+                reviewers):
+  """Prints info about a CL.
+
+  Args:
+    cl_index: The index of this CL in the list of CLs to upload.
+    num_cls: The total number of CLs that will be uploaded.
+    directory: Path to the directory that contains the OWNERS file for which
+        to upload a CL.
+    file_paths: A list of files in this CL.
+    description: The CL description.
+    reviewers: A set of reviewers for this CL.
+  """
+  description_lines = FormatDescriptionOrComment(description,
+                                                 directory).splitlines()
+  indented_description = '\n'.join(['    ' + l for l in description_lines])
+
+  print 'CL {}/{}'.format(cl_index, num_cls)
+  print 'Path: {}'.format(directory)
+  print 'Reviewers: {}'.format(', '.join(reviewers))
+  print '\n' + indented_description + '\n'
+  print '\n'.join(file_paths)
+  print
+
+
+def SplitCl(description_file, comment_file, changelist, cmd_upload, dry_run):
   """"Splits a branch into smaller branches and uploads CLs.
 
   Args:
@@ -144,6 +164,7 @@ def SplitCl(description_file, comment_file, changelist, cmd_upload):
     comment_file: File containing the comment of uploaded CLs.
     changelist: The Changelist class.
     cmd_upload: The function associated with the git cl upload command.
+    dry_run: Whether this is a dry run (no branches or CLs created).
 
   Returns:
     0 in case of success. 1 in case of error.
@@ -152,7 +173,7 @@ def SplitCl(description_file, comment_file, changelist, cmd_upload):
   comment = ReadFile(comment_file) if comment_file else None
 
   try:
-    EnsureInGitRepository();
+    EnsureInGitRepository()
 
     cl = changelist()
     change = cl.GetChange(cl.GetCommonAncestorWithUpstream(), None)
@@ -172,20 +193,26 @@ def SplitCl(description_file, comment_file, changelist, cmd_upload):
     owners_database = owners.Database(change.RepositoryRoot(), file, os.path)
     owners_database.load_data_needed_for([f.LocalPath() for f in files])
 
-    files_split_by_owners = GetFilesSplitByOwners(
-        owners_database, files)
+    files_split_by_owners = GetFilesSplitByOwners(owners_database, files)
 
-    print ('Will split current branch (' + refactor_branch +') in ' +
-           str(len(files_split_by_owners)) + ' CLs.\n')
+    num_cls = len(files_split_by_owners)
+    print('Will split current branch (' + refactor_branch + ') into ' +
+          str(num_cls) + ' CLs.\n')
 
-    for directory, files in files_split_by_owners.iteritems():
+    for cl_index, (directory, files) in \
+        enumerate(files_split_by_owners.iteritems(), 1):
       # Use '/' as a path separator in the branch name and the CL description
       # and comment.
       directory = directory.replace(os.path.sep, '/')
-      # Upload the CL.
-      UploadCl(refactor_branch, refactor_branch_upstream, directory, files,
-               author, description, comment, owners_database, changelist,
-               cmd_upload)
+      file_paths = [f.LocalPath() for f in files]
+      reviewers = owners_database.reviewers_for(file_paths, author)
+
+      if dry_run:
+        PrintClInfo(cl_index, num_cls, directory, file_paths, description,
+                    reviewers)
+      else:
+        UploadCl(refactor_branch, refactor_branch_upstream, directory, files,
+                 description, comment, reviewers, changelist, cmd_upload)
 
     # Go back to the original branch.
     git.run('checkout', refactor_branch)