Add --generate_diff flag to presubmit_support.py

This flag allows a diff to be generated based on an upstream commit
for provided files and for checks to be run with on that diff.

Bug: b/323243527
Change-Id: Ia3f4ec50b15eabb90d391b9bc795fc4b35a35a08
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5376402
Reviewed-by: Josip Sokcevic <sokcevic@chromium.org>
Commit-Queue: Gavin Mak <gavinmak@google.com>

presubmit_support.py

@@ -18,7 +18,6 @@ import cpplint
 import fnmatch  # Exposed through the API.
 import glob
 import inspect
-import itertools
 import json  # Exposed through the API.
 import logging
 import mimetypes
@@ -49,6 +48,7 @@ import gerrit_util
 import owners_client
 import owners_finder
 import presubmit_canned_checks
+import presubmit_diff
 import rdb_wrapper
 import scm
 import subprocess2 as subprocess  # Exposed through the API.
@@ -2070,6 +2070,10 @@ def _parse_change(parser, options):
             parser.error(
                 '<diff_file> cannot be specified when --all-files is set.')
 
+    if options.diff_file and options.generate_diff:
+        parser.error(
+            '<diff_file> cannot be specified when <generate_diff> is set.')
+
     # TODO(b/323243527): Consider adding a SCM for provided diff.
     change_scm = scm.determine_scm(options.root)
     if change_scm != 'git' and not options.files and not options.diff_file:
@@ -2086,6 +2090,17 @@ def _parse_change(parser, options):
                     if fnmatch.fnmatch(name, mask):
                         change_files.append(('M', name))
                         break
+        elif options.generate_diff:
+            gerrit_url = urlparse.urlparse(options.gerrit_url).netloc
+            diffs = presubmit_diff.create_diffs(
+                host=gerrit_url.split('-review')[0],
+                repo=options.gerrit_project,
+                ref=options.upstream,
+                root=options.root,
+                files=options.files,
+            )
+            diff = '\n'.join(diffs.values())
+            change_files = _diffs_to_change_files(diffs)
         else:
             # Get the filtered set of files from a directory scan.
             change_files = _parse_files(options.files, options.recursive)
@@ -2169,7 +2184,14 @@ def _parse_unified_diff(diff):
 
 
 def _process_diff_file(diff_file):
-    """Validates a git diff file and processes it into a list of change files.
+    diff = gclient_utils.FileRead(diff_file)
+    if not diff:
+        raise PresubmitFailure('diff file is empty')
+    return diff, _diffs_to_change_files(_parse_unified_diff(diff))
+
+
+def _diffs_to_change_files(diffs):
+    """Validates a dict of diffs and processes it into a list of change files.
 
     Each change file is a tuple of (action, path) where action is one of:
         * A: newly added file
@@ -2177,20 +2199,16 @@ def _process_diff_file(diff_file):
         * D: deleted file
 
     Args:
-        diff_file: Path to file containing unified git diff.
+        diffs: Dict of (path, diff) tuples.
 
     Returns:
-        Contents of diff_file and a list of change file tuples from the diff.
+        A list of change file tuples from the diffs.
 
     Raises:
-        PresubmitFailure: If the provided diff is empty or otherwise invalid.
+        PresubmitFailure: If a diff is empty or otherwise invalid.
     """
-    diff = gclient_utils.FileRead(diff_file)
-    if not diff:
-        raise PresubmitFailure('diff file is empty')
-
     change_files = []
-    for file, file_diff in _parse_unified_diff(diff).items():
+    for file, file_diff in diffs.items():
         header_line = file_diff.splitlines()[1]
         if not header_line:
             raise PresubmitFailure('diff header is empty')
@@ -2201,7 +2219,7 @@ def _process_diff_file(diff_file):
         else:
             action = 'M'
         change_files.append((action, file))
-    return diff, change_files
+    return change_files
 
 
 @contextlib.contextmanager
@@ -2276,6 +2294,9 @@ def main(argv=None):
     desc.add_argument('--description_file',
                       help='File to read change description from.')
     parser.add_argument('--diff_file', help='File to read change diff from.')
+    parser.add_argument('--generate_diff',
+                        action='store_true',
+                        help='Create a diff using upstream server as base.')
     parser.add_argument('--issue', type=int, default=0)
     parser.add_argument('--patchset', type=int, default=0)
     parser.add_argument('--root',
@@ -2284,10 +2305,9 @@ def main(argv=None):
                         'If inherit-review-settings-ok is present in this '
                         'directory, parent directories up to the root file '
                         'system directories will also be searched.')
-    parser.add_argument(
-        '--upstream',
-        help='Git only: the base ref or upstream branch against '
-        'which the diff should be computed.')
+    parser.add_argument('--upstream',
+                        help='The base ref or upstream branch against '
+                        'which the diff should be computed.')
     parser.add_argument('--default_presubmit')
     parser.add_argument('--may_prompt', action='store_true', default=False)
     parser.add_argument(

tests/presubmit_support_test.py

@@ -66,6 +66,7 @@ class ProvidedDiffChangeTest(fake_repos.FakeReposTestBase):
             gclient_utils.FileWrite(tmp, diff)
             options = mock.Mock(root=self.repo,
                                 all_files=False,
+                                generate_diff=False,
                                 description='description',
                                 files=None,
                                 diff_file=tmp)

tests/presubmit_unittest.py

@@ -966,7 +966,9 @@ def CheckChangeOnCommit(input_api, output_api):
     def testParseChange_Files(self):
         presubmit._parse_files.return_value = [('M', 'random_file.txt')]
         scm.determine_scm.return_value = None
-        options = mock.Mock(all_files=False, source_controlled_only=False)
+        options = mock.Mock(all_files=False,
+                            generate_diff=False,
+                            source_controlled_only=False)
 
         change = presubmit._parse_change(None, options)
         self.assertEqual(presubmit.Change.return_value, change)
@@ -1009,11 +1011,26 @@ def CheckChangeOnCommit(input_api, output_api):
         parser.error.assert_called_once_with(
             '<diff_file> cannot be specified when --all-files is set.')
 
+    def testParseChange_DiffAndGenerateDiff(self):
+        parser = mock.Mock()
+        parser.error.side_effect = [SystemExit]
+        options = mock.Mock(all_files=False,
+                            files=[],
+                            generate_diff=True,
+                            diff_file='foo.diff')
+
+        with self.assertRaises(SystemExit):
+            presubmit._parse_change(parser, options)
+        parser.error.assert_called_once_with(
+            '<diff_file> cannot be specified when <generate_diff> is set.')
+
     @mock.patch('presubmit_support.GitChange', mock.Mock())
     def testParseChange_FilesAndGit(self):
         scm.determine_scm.return_value = 'git'
         presubmit._parse_files.return_value = [('M', 'random_file.txt')]
-        options = mock.Mock(all_files=False, source_controlled_only=False)
+        options = mock.Mock(all_files=False,
+                            generate_diff=False,
+                            source_controlled_only=False)
 
         change = presubmit._parse_change(None, options)
         self.assertEqual(presubmit.GitChange.return_value, change)
@@ -1071,7 +1088,10 @@ def CheckChangeOnCommit(input_api, output_api):
 
     def testParseChange_EmptyDiffFile(self):
         gclient_utils.FileRead.return_value = ''
-        options = mock.Mock(all_files=False, files=[], diff_file='foo.diff')
+        options = mock.Mock(all_files=False,
+                            files=[],
+                            generate_diff=False,
+                            diff_file='foo.diff')
         with self.assertRaises(presubmit.PresubmitFailure):
             presubmit._parse_change(None, options)
 
@@ -1100,7 +1120,10 @@ index d7ba659f..b7957f3 100644
 -baz
 +bat"""
         gclient_utils.FileRead.return_value = diff
-        options = mock.Mock(all_files=False, files=[], diff_file='foo.diff')
+        options = mock.Mock(all_files=False,
+                            files=[],
+                            generate_diff=False,
+                            diff_file='foo.diff')
         change = presubmit._parse_change(None, options)
         self.assertEqual(presubmit.ProvidedDiffChange.return_value, change)
         presubmit.ProvidedDiffChange.assert_called_once_with(