Refactor infra git libs and testing.

infra/libs/git2/test/commit_test.py

+# Copyright 2014 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.
+
+from infra.libs import git2
+from infra.libs.git2.test import test_util
+
+
+class TestCommit(test_util.TestBasis):
+  def testComparison(self):
+    r = self.mkRepo()
+    c = r['refs/heads/branch_O'].commit
+    self.assertEqual(c, c)
+    self.assertEqual(c, r['refs/heads/branch_O'].commit)
+    self.assertNotEqual(c, r['refs/heads/branch_S'].commit)
+    self.assertIs(c.repo, r)
+
+  def testRepr(self):
+    r = self.mkRepo()
+    c = r['refs/heads/branch_O'].commit
+    self.assertEqual("Commit(%r, %r)" % (r, self.repo['O']), repr(c))
+
+  def testData(self):
+    r = self.mkRepo()
+    d = r['refs/heads/branch_O'].commit.data
+    self.assertEqual(d.committer.email, 'commitish@example.com')
+
+  def testBogus(self):
+    r = self.mkRepo()
+    d = git2.Commit(r, 'deadbeefdeadbeefdeadbeefdeadbeefdeadbeef').data
+    self.assertIs(d, git2.INVALID)
+    self.assertIs(d.committer, git2.INVALID)
+    self.assertIs(d.committer.alter(user='tom'), git2.INVALID)
+
+  def testParent(self):
+    r = self.mkRepo()
+    c = r['refs/heads/branch_O'].commit
+    self.assertEqual(c.parent.hsh, self.repo['N'])
+
+    a = r['refs/heads/root_A'].commit
+    self.assertIsNone(a.parent)
+
+    z = r['refs/heads/branch_Z'].commit
+    self.assertIs(z.parent, git2.INVALID)
+
+  def testAlter(self):
+    r = self.mkRepo()
+    c = r['refs/heads/branch_O'].commit
+    d = c.data
+
+    a = c.alter(committer=d.committer.alter(email='bob@dude.example.com'))
+    self.assertEqual(a.hsh, 'fadfbe63d40f60f5313a71a1c9d72a741ee91770')
+
+    with self.assertRaises(Exception):
+      c.alter(tree='failbeef')
+