test utils: implement a repo context manager

The current hierarchy of test cases that create and blow away test
repositories in the ``setUp`` and ``tearDown`` methods is inadequate
for testing scenarios where multiple repositories must be edited,
e.g.  testing push.

Extract the temporary repository behaviour into a context manager
class ``TemporaryRepository`` which can be used via the ``with``
keyword.  The context manager's ``__enter__` method returns creates
the specified repository in a temporary directory and returns its
path.  The temporary directory is removed in ``__exit__``.

Update the existing test case base classes to use the context
manager and invoke ``__enter__`` and ``__exit__`` in the ``setUp``
and ``tearDown`` methods respectively.

Finally, make some small tweaks to a handful of tests to get them
working under this new system.

test/test_blob.py

@@ -93,13 +93,12 @@ class BlobTest(utils.RepoTestCase):
 
 
     def test_create_blob_outside_workdir(self):
-        path = join(dirname(__file__), 'data', self.repo_dir + '.tar')
+        path = __file__
         self.assertRaises(KeyError, self.repo.create_blob_fromworkdir, path)
 
 
     def test_create_blob_fromdisk(self):
-        path = join(dirname(__file__), 'data', self.repo_dir + '.tar')
-        blob_oid = self.repo.create_blob_fromdisk(path)
+        blob_oid = self.repo.create_blob_fromdisk(__file__)
         blob = self.repo[blob_oid]
 
         self.assertTrue(isinstance(blob, pygit2.Blob))

test/test_repository.py

@@ -143,7 +143,7 @@ class RepositoryTest(utils.BareRepoTestCase):
 
     def test_get_path(self):
         directory = realpath(self.repo.path)
-        expected = realpath(join(self._temp_dir, 'testrepo.git'))
+        expected = realpath(self.repo_path)
         self.assertEqual(directory, expected)
 
     def test_get_workdir(self):
@@ -179,12 +179,12 @@ class RepositoryTest_II(utils.RepoTestCase):
 
     def test_get_path(self):
         directory = realpath(self.repo.path)
-        expected = realpath(join(self._temp_dir, 'testrepo', '.git'))
+        expected = realpath(join(self.repo_path, '.git'))
         self.assertEqual(directory, expected)
 
     def test_get_workdir(self):
         directory = realpath(self.repo.workdir)
-        expected = realpath(join(self._temp_dir, 'testrepo'))
+        expected = realpath(self.repo_path)
         self.assertEqual(directory, expected)
 
     def test_checkout_ref(self):

test/utils.py

@@ -65,6 +65,27 @@ def rmtree(path):
         shutil.rmtree(path, onerror=onerror)
 
 
+class TemporaryRepository(object):
+    def __init__(self, repo_spec):
+        self.repo_spec = repo_spec
+
+    def __enter__(self):
+        container, name = self.repo_spec
+        repo_path = os.path.join(os.path.dirname(__file__), 'data', name)
+        self.temp_dir = tempfile.mkdtemp()
+        temp_repo_path = os.path.join(self.temp_dir, name)
+        if container == 'tar':
+            tar = tarfile.open('.'.join((repo_path, 'tar')))
+            tar.extractall(self.temp_dir)
+            tar.close()
+        else:
+            shutil.copytree(repo_path, temp_repo_path)
+        return temp_repo_path
+
+    def __exit__(self, exc_type, exc_value, traceback):
+        rmtree(self.temp_dir)
+
+
 class NoRepoTestCase(unittest.TestCase):
 
     def setUp(self):
@@ -103,45 +124,33 @@ class NoRepoTestCase(unittest.TestCase):
         self.assertEqual(a.offset, b.offset)
 
 
-class BareRepoTestCase(NoRepoTestCase):
-
-    repo_dir = 'testrepo.git'
-
+class AutoRepoTestCase(NoRepoTestCase):
     def setUp(self):
-        super(BareRepoTestCase, self).setUp()
+        super(AutoRepoTestCase, self).setUp()
+        self.repo_ctxtmgr = TemporaryRepository(self.repo_spec)
+        self.repo_path = self.repo_ctxtmgr.__enter__()
+        self.repo = pygit2.Repository(self.repo_path)
 
-        repo_dir = self.repo_dir
-        repo_path = os.path.join(os.path.dirname(__file__), 'data', repo_dir)
-        temp_repo_path = os.path.join(self._temp_dir, repo_dir)
-
-        shutil.copytree(repo_path, temp_repo_path)
-
-        self.repo = pygit2.Repository(temp_repo_path)
+    def tearDown(self):
+        self.repo_ctxtmgr.__exit__(None, None, None)
+        super(AutoRepoTestCase, self).tearDown()
 
 
-class RepoTestCase(NoRepoTestCase):
+class BareRepoTestCase(AutoRepoTestCase):
 
-    repo_dir = 'testrepo'
-
-    def setUp(self):
-        super(RepoTestCase, self).setUp()
-
-        repo_dir = self.repo_dir
-        repo_path = os.path.join(os.path.dirname(__file__), 'data', repo_dir)
-        temp_repo_path = os.path.join(self._temp_dir, repo_dir, '.git')
-
-        tar = tarfile.open(repo_path + '.tar')
-        tar.extractall(self._temp_dir)
-        tar.close()
-
-        self.repo = pygit2.Repository(temp_repo_path)
+    repo_spec = 'git', 'testrepo.git'
 
 
-class DirtyRepoTestCase(RepoTestCase):
+class RepoTestCase(AutoRepoTestCase):
 
-    repo_dir = 'dirtyrepo'
+    repo_spec = 'tar', 'testrepo'
 
 
-class EmptyRepoTestCase(RepoTestCase):
+class DirtyRepoTestCase(AutoRepoTestCase):
 
-    repo_dir = 'emptyrepo'
+    repo_spec = 'tar', 'dirtyrepo'
+
+
+class EmptyRepoTestCase(AutoRepoTestCase):
+
+    repo_spec = 'tar', 'emptyrepo'