Implement support for change info thru diff file

This will be used in cases where git workspace is unavailable.

Bug: b/323243527
Change-Id: I51056cfbac50f76a0de1b98cfec488d8f133e353
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5263021
Commit-Queue: Gavin Mak <gavinmak@google.com>
Reviewed-by: Joanna Wang <jojwang@chromium.org>

presubmit_support.py

@@ -21,8 +21,10 @@ import inspect
 import itertools
 import json  # Exposed through the API.
 import logging
+import mimetypes
 import multiprocessing
 import os  # Somewhat exposed through the API.
+import pathlib
 import random
 import re  # Exposed through the API.
 import signal
@@ -935,36 +937,15 @@ class _GitDiffCache(_DiffCache):
         # Compare against None to distinguish between None and an initialized
         # but empty dictionary.
         if self._diffs_by_file == None:
-            # Compute a single diff for all files and parse the output; should
-            # with git this is much faster than computing one diff for each
-            # file.
-            diffs = {}
-
             # Don't specify any filenames below, because there are command line
             # length limits on some platforms and GenerateDiff would fail.
             unified_diff = scm.GIT.GenerateDiff(local_root,
                                                 files=[],
                                                 full_move=True,
                                                 branch=self._upstream)
-
-            # This regex matches the path twice, separated by a space. Note that
-            # filename itself may contain spaces.
-            file_marker = re.compile(
-                '^diff --git (?P<filename>.*) (?P=filename)$')
-            current_diff = []
-            keep_line_endings = True
-            for x in unified_diff.splitlines(keep_line_endings):
-                match = file_marker.match(x)
-                if match:
-                    # Marks the start of a new per-file section.
-                    diffs[match.group('filename')] = current_diff = [x]
-                elif x.startswith('diff --git'):
-                    raise PresubmitFailure('Unexpected diff line: %s' % x)
-                else:
-                    current_diff.append(x)
-
-            self._diffs_by_file = dict(
-                (normpath(path), ''.join(diff)) for path, diff in diffs.items())
+            # Compute a single diff for all files and parse the output; with git
+            # this is much faster than computing one diff for each file.
+            self._diffs_by_file = _parse_unified_diff(unified_diff)
 
         if path not in self._diffs_by_file:
             # SCM didn't have any diff on this file. It could be that the file
@@ -979,6 +960,27 @@ class _GitDiffCache(_DiffCache):
         return scm.GIT.GetOldContents(local_root, path, branch=self._upstream)
 
 
+class _ProvidedDiffCache(_DiffCache):
+    """Caches diffs from the provided diff file."""
+
+    def __init__(self, diff):
+        """Stores all diffs and diffs per file."""
+        super(_ProvidedDiffCache, self).__init__()
+        self._diffs_by_file = None
+        self._diff = diff
+
+    def GetDiff(self, path, local_root):
+        """Get the diff for a particular path."""
+        if self._diffs_by_file == None:
+            self._diffs_by_file = _parse_unified_diff(self._diff)
+        return self._diffs_by_file.get(path, '')
+
+    def GetOldContents(self, path, local_root):
+        """Get the old version for a particular path."""
+        # TODO(gavinmak): Implement with self._diff.
+        return ''
+
+
 class AffectedFile(object):
     """Representation of a file in a change."""
 
@@ -994,6 +996,7 @@ class AffectedFile(object):
         self._cached_changed_contents = None
         self._cached_new_contents = None
         self._diff_cache = diff_cache
+        self._is_testable_file = None
         logging.debug('%s(%s)', self.__class__.__name__, self._path)
 
     def LocalPath(self):
@@ -1017,7 +1020,14 @@ class AffectedFile(object):
         """Returns True if the file is a text file and not a binary file.
 
         Deleted files are not text file."""
-        raise NotImplementedError()  # Implement when needed
+        if self._is_testable_file is None:
+            if self.Action() == 'D':
+                # A deleted file is not testable.
+                self._is_testable_file = False
+            else:
+                t, _ = mimetypes.guess_type(self.AbsoluteLocalPath())
+                self._is_testable_file = bool(t and t.startswith('text/'))
+        return self._is_testable_file
 
     def IsTextFile(self):
         """An alias to IsTestableFile for backwards compatibility."""
@@ -1106,8 +1116,6 @@ class GitAffectedFile(AffectedFile):
 
     def __init__(self, *args, **kwargs):
         AffectedFile.__init__(self, *args, **kwargs)
-        self._server_path = None
-        self._is_testable_file = None
 
     def IsTestableFile(self):
         if self._is_testable_file is None:
@@ -1120,6 +1128,11 @@ class GitAffectedFile(AffectedFile):
         return self._is_testable_file
 
 
+class ProvidedDiffAffectedFile(AffectedFile):
+    """Representation of a file in a change described by a diff."""
+    DIFF_CACHE = _ProvidedDiffCache
+
+
 class Change(object):
     """Describe a change.
 
@@ -1437,6 +1450,25 @@ class GitChange(Change):
         ]
 
 
+class ProvidedDiffChange(Change):
+    _AFFECTED_FILES = ProvidedDiffAffectedFile
+
+    def __init__(self, *args, diff, **kwargs):
+        self._diff = diff
+        super(ProvidedDiffChange, self).__init__(*args)
+
+    def _diff_cache(self):
+        return self._AFFECTED_FILES.DIFF_CACHE(self._diff)
+
+    def AllFiles(self, root=None):
+        """List all files under source control in the repo.
+
+        There is no SCM, so return all files under the repo root.
+        """
+        root = root or self.RepositoryRoot()
+        return [str(p) for p in pathlib.Path(root).rglob("*")]
+
+
 def ListRelevantPresubmitFiles(files, root):
     """Finds all presubmit files that apply to a given set of source files.
 
@@ -1989,15 +2021,23 @@ def _parse_change(parser, options):
         parser: The parser used to parse the arguments from command line.
         options: The arguments parsed from command line.
     Returns:
-        A GitChange if the change root is a git repository, or a Change otherwise.
+        A GitChange if the change root is a git repository, a ProvidedDiffChange
+        if a diff file is specified, or a Change otherwise.
     """
-    if options.files and options.all_files:
-        parser.error('<files> cannot be specified when --all-files is set.')
-
+    if options.all_files:
+        if options.files:
+            parser.error('<files> cannot be specified when --all-files is set.')
+        if options.diff_file:
+            parser.error(
+                '<diff_file> cannot be specified when --all-files 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:
-        parser.error('<files> is not optional for unversioned directories.')
+    if change_scm != 'git' and not options.files and not options.diff_file:
+        parser.error(
+            'unversioned directories must specify <files> or <diff_file>.')
 
+    diff = None
     if options.files:
         if options.source_controlled_only:
             # Get the filtered set of files from SCM.
@@ -2012,6 +2052,8 @@ def _parse_change(parser, options):
             change_files = _parse_files(options.files, options.recursive)
     elif options.all_files:
         change_files = [('M', f) for f in scm.GIT.GetAllFiles(options.root)]
+    elif options.diff_file:
+        diff, change_files = _process_diff_file(options.diff_file)
     else:
         change_files = scm.GIT.CaptureStatus(options.root,
                                              options.upstream or None,
@@ -2024,6 +2066,8 @@ def _parse_change(parser, options):
     ]
     if change_scm == 'git':
         return GitChange(*change_args, upstream=options.upstream)
+    if diff:
+        return ProvidedDiffChange(*change_args, diff=diff)
     return Change(*change_args)
 
 
@@ -2062,6 +2106,64 @@ def _parse_gerrit_options(parser, options):
     return gerrit_obj
 
 
+def _parse_unified_diff(diff):
+    """Parses a unified git diff and returns a list of (path, diff) tuples."""
+    diffs = {}
+
+    # This regex matches the path twice, separated by a space. Note that
+    # filename itself may contain spaces.
+    file_marker = re.compile(
+        '^diff --git (?:a/)?(?P<filename>.*) (?:b/)?(?P=filename)$')
+    current_diff = []
+    keep_line_endings = True
+    for x in diff.splitlines(keep_line_endings):
+        match = file_marker.match(x)
+        if match:
+            # Marks the start of a new per-file section.
+            diffs[match.group('filename')] = current_diff = [x]
+        elif x.startswith('diff --git'):
+            raise PresubmitFailure('Unexpected diff line: %s' % x)
+        else:
+            current_diff.append(x)
+
+    return dict((normpath(path), ''.join(diff)) for path, diff in diffs.items())
+
+
+def _process_diff_file(diff_file):
+    """Validates a git diff file 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
+        * M: modified file
+        * D: deleted file
+
+    Args:
+        diff_file: Path to file containing unified git diff.
+
+    Returns:
+        Contents of diff_file and a list of change file tuples from the diff.
+
+    Raises:
+        PresubmitFailure: If the provided 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():
+        header_line = file_diff.splitlines()[1]
+        if not header_line:
+            raise PresubmitFailure('diff header is empty')
+        if header_line.startswith('new'):
+            action = 'A'
+        elif header_line.startswith('deleted'):
+            action = 'D'
+        else:
+            action = 'M'
+        change_files.append((action, file))
+    return diff, change_files
+
 @contextlib.contextmanager
 def setup_environ(kv: Mapping[str, str]):
     """Update environment while in context, and reset back to original on exit.
@@ -2133,6 +2235,7 @@ def main(argv=None):
                       help='The change description.')
     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('--issue', type=int, default=0)
     parser.add_argument('--patchset', type=int, default=0)
     parser.add_argument('--root',

tests/presubmit_support_test.py

@@ -4,13 +4,14 @@
 # found in the LICENSE file.
 
 import os.path
-import subprocess
 import sys
+import tempfile
 import unittest
 
 ROOT_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 sys.path.insert(0, ROOT_DIR)
 
+import gclient_utils
 import presubmit_support
 
 
@@ -24,5 +25,159 @@ class PresubmitSupportTest(unittest.TestCase):
         self.assertIsNone(os.environ.get('PRESUBMIT_FOO_ENV', None))
 
 
+class TestParseDiff(unittest.TestCase):
+    """A suite of tests related to diff parsing and processing."""
+
+    def _test_diff_to_change_files(self, diff, expected):
+        with gclient_utils.temporary_file() as tmp:
+            gclient_utils.FileWrite(tmp, diff, mode='w+')
+            content, change_files = presubmit_support._process_diff_file(tmp)
+            self.assertCountEqual(content, diff)
+            self.assertCountEqual(change_files, expected)
+
+    def test_diff_to_change_files_raises_on_empty_file(self):
+        with self.assertRaises(presubmit_support.PresubmitFailure):
+            self._test_diff_to_change_files(diff='', expected=[])
+
+    def test_diff_to_change_files_raises_on_empty_diff_header(self):
+        diff = """
+diff --git a/foo b/foo
+
+"""
+        with self.assertRaises(presubmit_support.PresubmitFailure):
+            self._test_diff_to_change_files(diff=diff, expected=[])
+
+    def test_diff_to_change_files_simple_add(self):
+        diff = """
+diff --git a/foo b/foo
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ b/foo
+@@ -0,0 +1 @@
++add
+"""
+        self._test_diff_to_change_files(diff=diff, expected=[('A', 'foo')])
+
+    def test_diff_to_change_files_simple_delete(self):
+        diff = """
+diff --git a/foo b/foo
+deleted file mode 100644
+index f675c2a..0000000
+--- a/foo
++++ /dev/null
+@@ -1,1 +0,0 @@
+-delete
+"""
+        self._test_diff_to_change_files(diff=diff, expected=[('D', 'foo')])
+
+    def test_diff_to_change_files_simple_modification(self):
+        diff = """
+diff --git a/foo b/foo
+index d7ba659f..b7957f3 100644
+--- a/foo
++++ b/foo
+@@ -29,7 +29,7 @@
+other
+random
+text
+-  foo1
++  foo2
+other
+random
+text
+"""
+        self._test_diff_to_change_files(diff=diff, expected=[('M', 'foo')])
+
+    def test_diff_to_change_files_multiple_changes(self):
+        diff = """
+diff --git a/foo b/foo
+index d7ba659f..b7957f3 100644
+--- a/foo
++++ b/foo
+@@ -29,7 +29,7 @@
+other
+random
+text
+-  foo1
++  foo2
+other
+random
+text
+diff --git a/bar b/bar
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ b/bar
+@@ -0,0 +1 @@
++add
+diff --git a/baz b/baz
+deleted file mode 100644
+index f675c2a..0000000
+--- a/baz
++++ /dev/null
+@@ -1,1 +0,0 @@
+-delete
+"""
+        self._test_diff_to_change_files(diff=diff,
+                                        expected=[('M', 'foo'), ('A', 'bar'),
+                                                  ('D', 'baz')])
+
+    def test_parse_unified_diff_with_valid_diff(self):
+        diff = """
+diff --git a/foo b/foo
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ b/foo
+@@ -0,0 +1 @@
++add
+"""
+        res = presubmit_support._parse_unified_diff(diff)
+        self.assertCountEqual(
+            res, {
+                'foo':
+                """
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ b/foo
+@@ -0,0 +1 @@
++add
+"""
+            })
+
+    def test_parse_unified_diff_with_valid_diff_noprefix(self):
+        diff = """
+diff --git foo foo
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ foo
+@@ -0,0 +1 @@
++add
+"""
+        res = presubmit_support._parse_unified_diff(diff)
+        self.assertCountEqual(
+            res, {
+                'foo':
+                """
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ foo
+@@ -0,0 +1 @@
++add
+"""
+            })
+
+    def test_parse_unified_diff_with_invalid_diff(self):
+        diff = """
+diff --git a/ffoo b/foo
+"""
+        with self.assertRaises(presubmit_support.PresubmitFailure):
+            presubmit_support._parse_unified_diff(diff)
+
+
 if __name__ == "__main__":
     unittest.main()

tests/presubmit_unittest.py

@@ -959,8 +959,8 @@ def CheckChangeOnCommit(input_api, output_api):
         self.assertEqual(
             sys.stderr.getvalue(),
             'usage: presubmit_unittest.py [options] <files...>\n'
-            'presubmit_unittest.py: error: <files> is not optional for unversioned '
-            'directories.\n')
+            'presubmit_unittest.py: error: unversioned directories must '
+            'specify <files> or <diff_file>.\n')
 
     @mock.patch('presubmit_support.Change', mock.Mock())
     def testParseChange_Files(self):
@@ -982,12 +982,12 @@ def CheckChangeOnCommit(input_api, output_api):
         scm.determine_scm.return_value = None
         parser = mock.Mock()
         parser.error.side_effect = [SystemExit]
-        options = mock.Mock(files=[], all_files=False)
+        options = mock.Mock(files=[], diff_file='', all_files=False)
 
         with self.assertRaises(SystemExit):
             presubmit._parse_change(parser, options)
         parser.error.assert_called_once_with(
-            '<files> is not optional for unversioned directories.')
+            'unversioned directories must specify <files> or <diff_file>.')
 
     def testParseChange_FilesAndAllFiles(self):
         parser = mock.Mock()
@@ -999,6 +999,16 @@ def CheckChangeOnCommit(input_api, output_api):
         parser.error.assert_called_once_with(
             '<files> cannot be specified when --all-files is set.')
 
+    def testParseChange_DiffAndAllFiles(self):
+        parser = mock.Mock()
+        parser.error.side_effect = [SystemExit]
+        options = mock.Mock(files=[], all_files=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 --all-files is set.')
+
     @mock.patch('presubmit_support.GitChange', mock.Mock())
     def testParseChange_FilesAndGit(self):
         scm.determine_scm.return_value = 'git'
@@ -1023,7 +1033,7 @@ def CheckChangeOnCommit(input_api, output_api):
     def testParseChange_NoFilesAndGit(self):
         scm.determine_scm.return_value = 'git'
         scm.GIT.CaptureStatus.return_value = [('A', 'added.txt')]
-        options = mock.Mock(all_files=False, files=[])
+        options = mock.Mock(all_files=False, files=[], diff_file='')
 
         change = presubmit._parse_change(None, options)
         self.assertEqual(presubmit.GitChange.return_value, change)
@@ -1044,7 +1054,7 @@ def CheckChangeOnCommit(input_api, output_api):
     def testParseChange_AllFilesAndGit(self):
         scm.determine_scm.return_value = 'git'
         scm.GIT.GetAllFiles.return_value = ['foo.txt', 'bar.txt']
-        options = mock.Mock(all_files=True, files=[])
+        options = mock.Mock(all_files=True, files=[], diff_file='')
 
         change = presubmit._parse_change(None, options)
         self.assertEqual(presubmit.GitChange.return_value, change)
@@ -1059,6 +1069,49 @@ def CheckChangeOnCommit(input_api, output_api):
                                                     upstream=options.upstream)
         scm.GIT.GetAllFiles.assert_called_once_with(options.root)
 
+    def testParseChange_EmptyDiffFile(self):
+        gclient_utils.FileRead.return_value = ''
+        options = mock.Mock(all_files=False, files=[], diff_file='foo.diff')
+        with self.assertRaises(presubmit.PresubmitFailure):
+            presubmit._parse_change(None, options)
+
+    @mock.patch('presubmit_support.ProvidedDiffChange', mock.Mock())
+    def testParseChange_ProvidedDiffFile(self):
+        diff = """
+diff --git a/foo b/foo
+new file mode 100644
+index 0000000..9daeafb
+--- /dev/null
++++ b/foo
+@@ -0,0 +1 @@
++test
+diff --git a/bar b/bar
+deleted file mode 100644
+index f675c2a..0000000
+--- a/bar
++++ /dev/null
+@@ -1,1 +0,0 @@
+-bar
+diff --git a/baz b/baz
+index d7ba659f..b7957f3 100644
+--- a/baz
++++ b/baz
+@@ -1,1 +1,1 @@
+-baz
++bat"""
+        gclient_utils.FileRead.return_value = diff
+        options = mock.Mock(all_files=False, files=[], diff_file='foo.diff')
+        change = presubmit._parse_change(None, options)
+        self.assertEqual(presubmit.ProvidedDiffChange.return_value, change)
+        presubmit.ProvidedDiffChange.assert_called_once_with(
+            options.name,
+            options.description,
+            options.root, [('A', 'foo'), ('D', 'bar'), ('M', 'baz')],
+            options.issue,
+            options.patchset,
+            options.author,
+            diff=diff)
+
     def testParseGerritOptions_NoGerritUrl(self):
         options = mock.Mock(gerrit_url=None,
                             gerrit_fetch=False,