Add git-number script to calculate generation numbers for commits.

tests/git_number_test.py

Index: tests/git_number_test.py
diff --git a/tests/git_number_test.py b/tests/git_number_test.py
new file mode 100755
index 0000000000000000000000000000000000000000..498c801b86da70e30d90373bcd97ba571d05148e
--- /dev/null
+++ b/tests/git_number_test.py
@@ -0,0 +1,85 @@
+#!/usr/bin/env python
+# Copyright (c) 2013 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Unit tests for git_number.py"""
+
+import binascii
+import os
+import sys
+
+DEPOT_TOOLS_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, DEPOT_TOOLS_ROOT)
+
+from testing_support import git_test_utils
+from testing_support import coverage_utils
+
+
+class Basic(git_test_utils.GitRepoReadWriteTestBase):
+  REPO = """
+  A B C D E
+    B   F E
+  X Y     E
+  """
+
+  @classmethod
+  def setUpClass(cls):
+    super(Basic, cls).setUpClass()
+    import git_number
+    cls.gn = git_number
+    cls.old_POOL_KIND = cls.gn.POOL_KIND
+    cls.gn.POOL_KIND = 'threads'
+
+  @classmethod
+  def tearDownClass(cls):
+    cls.gn.POOL_KIND = cls.old_POOL_KIND
+    super(Basic, cls).tearDownClass()
+
+  def tearDown(self):
+    self.gn.clear_caches()
+    super(Basic, self).tearDown()
+
+  def _git_number(self, refs, cache=False):
+    refs = map(binascii.unhexlify, refs)
+    self.repo.run(self.gn.load_generation_numbers, refs)
+    if cache:
+      self.repo.run(self.gn.finalize, refs)
+    return map(self.gn.get_num, refs)
+
+  def testBasic(self):
+    self.assertEqual([0], self._git_number([self.repo['A']]))
+    self.assertEqual([2], self._git_number([self.repo['F']]))
+    self.assertEqual([0], self._git_number([self.repo['X']]))
+    self.assertEqual([4], self._git_number([self.repo['E']]))
+
+  def testInProcessCache(self):
+    self.assertEqual(
+      None, self.repo.run(self.gn.get_num, binascii.unhexlify(self.repo['A']))
+    )

[M-A Ruel, 2013/11/17 19:54:58]

Not my favorite layout, in general I prefer:
self.assertEqual(
    None,
    self.repo.run(self.gn.get_num, binascii.unhexlify(self.repo['A'])))

In particular for an unknown reason, you are aligning at +2.

[iannucci, 2013/11/18 05:38:56]

Done.

TBH, I'm unclear on the +4 rule. That's any time you're doing any sort of () or
{} or []? Also, why +4 when the indent size is +2? Google style guide is +4, but
their normal indent is also +4, I assumed the two were linked?

+    self.assertEqual([4], self._git_number([self.repo['E']]))
+    self.assertEqual(
+      0, self.repo.run(self.gn.get_num, binascii.unhexlify(self.repo['A']))
+    )
+
+  def testOnDiskCache(self):
+    self.assertEqual(
+      None, self.repo.run(self.gn.get_num, binascii.unhexlify(self.repo['A']))
+    )
+    self.assertEqual([4], self._git_number([self.repo['E']], cache=True))
+    self.assertEqual([4], self._git_number([self.repo['E']], cache=True))
+    self.gn.clear_caches()
+    self.assertEqual(
+      0, self.repo.run(self.gn.get_num, binascii.unhexlify(self.repo['A']))
+    )
+    self.gn.clear_caches()
+    self.repo.run(self.gn.clear_caches, True)
+    self.assertEqual(
+      None, self.repo.run(self.gn.get_num, binascii.unhexlify(self.repo['A']))
+    )
+
+
+if __name__ == '__main__':
+  sys.exit(coverage_utils.covered_main(
+    os.path.join(DEPOT_TOOLS_ROOT, 'git_number.py')
+  ))