add NewGitCheckout to git_utils.py

py/utils/git_utils_test.py

Index: py/utils/git_utils_test.py
diff --git a/py/utils/git_utils_test.py b/py/utils/git_utils_test.py
new file mode 100755
index 0000000000000000000000000000000000000000..88a273693264850764c1b3064b4a178678088b3e
--- /dev/null
+++ b/py/utils/git_utils_test.py
@@ -0,0 +1,103 @@
+#!/usr/bin/python
+
+"""
+Copyright 2014 Google Inc.
+
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+
+Test git_utils.py.
+"""
+
+# System-level imports
+import os
+import tempfile
+import unittest
+
+# Imports from within Skia
+import git_utils
+
+
+# A git repo we can use for tests.
+REPO = 'https://skia.googlesource.com/common'
+
+# A file in some subdirectory within REPO.
+REPO_FILE = os.path.join('py', 'utils', 'git_utils.py')
+
+
+class NewGitCheckoutTest(unittest.TestCase):
+
+  def test_defaults(self):
+    """Test NewGitCheckout created using default parameters."""
+    with git_utils.NewGitCheckout(repository=REPO) as checkout:
+      filepath = os.path.join(checkout.root, REPO_FILE)
+      self.assertTrue(
+          os.path.exists(filepath),
+          'file %s should exist' % filepath)
+    # Confirm that NewGitCheckout cleaned up after itself.
+    self.assertFalse(
+        os.path.exists(filepath),
+        'file %s should not exist' % filepath)
+
+  def test_subdir(self):
+    """Create NewGitCheckout with a specific subdirectory."""
+    subdir = os.path.dirname(REPO_FILE)
+    file_within_subdir = os.path.basename(REPO_FILE)
+
+    containing_dir = tempfile.mkdtemp()
+    try:
+      with git_utils.NewGitCheckout(repository=REPO, subdir=subdir,
+                                    containing_dir=containing_dir) as checkout:
+        self.assertTrue(
+            checkout.root.startswith(containing_dir),
+            'checkout.root %s should be within %s' % (
+                checkout.root, containing_dir))
+        filepath = os.path.join(checkout.root, file_within_subdir)
+        self.assertTrue(
+            os.path.exists(filepath),
+            'file %s should exist' % filepath)
+    finally:
+      os.rmdir(containing_dir)
+
+  def test_refspec(self):
+    """Create NewGitCheckout with a specific refspec.
+
+    This test depends on the fact that the whitespace.txt file was added to the
+    repo in a particular commit.
+    See https://skia.googlesource.com/common/+/c2200447734f13070fb3b2808dea58847241ab0e
+    ('Initial commit of whitespace.txt')
+    """
+    filename = 'whitespace.txt'
+    hash_without_file = 'f63e1cfff23615157e28942af5f5e8298351cb10'
+    hash_with_file = 'c2200447734f13070fb3b2808dea58847241ab0e'
+
+    with git_utils.NewGitCheckout(
+        repository=REPO, refspec=hash_without_file) as checkout:
+      filepath = os.path.join(checkout.root, filename)
+      self.assertEquals(
+          hash_without_file, checkout.commithash(),
+          '"%s" != "%s"' % (hash_without_file, checkout.commithash()))
+      self.assertFalse(
+          os.path.exists(filepath),
+          'file %s should not exist' % filepath)
+
+    with git_utils.NewGitCheckout(
+        repository=REPO, refspec=hash_with_file) as checkout:
+      filepath = os.path.join(checkout.root, filename)
+      self.assertEquals(
+          hash_with_file, checkout.commithash(),
+          '"%s" != "%s"' % (hash_with_file, checkout.commithash()))
+      self.assertTrue(
+          os.path.exists(filepath),
+          'file %s should exist' % filepath)
+
+
+def main(test_case_class):
+  """Run the unit tests within this class."""
+  suite = unittest.TestLoader().loadTestsFromTestCase(NewGitCheckoutTest)
+  results = unittest.TextTestRunner(verbosity=2).run(suite)
+  if not results.wasSuccessful():
+    raise Exception('failed unittest %s' % test_case_class)
+
+if __name__ == '__main__':
+  main(NewGitCheckoutTest)