Add CachedRepo class with tests.

3 files changed, 329 insertions, 0 deletions

diff --git a/morphlib/__init__.py b/morphlib/__init__.py
index a9281b85..62a4ab7c 100644
--- a/morphlib/__init__.py
+++ b/morphlib/__init__.py
@@ -25,6 +25,7 @@ import buildsystem
 import buildworker
 import builder
 import cachedir
+import cachedrepo
 import execute
 import fsutils
 import git
diff --git a/morphlib/cachedrepo.py b/morphlib/cachedrepo.py
new file mode 100644
index 00000000..998ba892
--- /dev/null
+++ b/morphlib/cachedrepo.py
@@ -0,0 +1,147 @@
+# Copyright (C) 2012  Codethink Limited
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+import binascii
+import cliapp
+import logging
+import os
+
+import morphlib.execute
+
+
+class InvalidReferenceError(cliapp.AppException):
+
+    def __init__(self, repo, ref):
+        Exception.__init__(self, '%s is an invalid reference for repo %s' %
+                           (ref, repo))
+
+
+class UnresolvedNamedReferenceError(cliapp.AppException):
+
+    def __init__(self, repo, ref):
+        Exception.__init__(self, '%s is not a SHA1 ref for repo %s' %
+                           (ref, repo))
+
+
+class CheckoutDirectoryExistsError(cliapp.AppException):
+
+    def __init__(self, repo, target_dir):
+        Exception.__init__(
+                self, 'Checkout directory %s for repo %s already exists' %
+                (target_dir, repo))
+
+
+class CheckoutError(cliapp.AppException):
+
+    def __init__(self, repo, ref, target_dir):
+        Exception.__init__(self, 'Failed to check out %s:%s into %s' %
+                           (repo, ref, target_dir))
+
+
+class UpdateError(cliapp.AppException):
+
+    def __init__(self, repo):
+        Exception.__init__(self, 'Failed to update cached version of repo %s' %
+                           repo)
+
+
+class CachedRepo(object):
+
+    def __init__(self, url, path):
+        self.url = url
+        self.path = path
+        self.ex = morphlib.execute.Execute(self.path, logging.debug)
+
+    def is_valid_sha1(self, ref):
+        valid_chars = 'abcdefABCDEF0123456789'
+        return len(ref) == 40 and all([x in valid_chars for x in ref])
+
+    def resolve_ref(self, ref):
+        try:
+            refs = self._show_ref(ref).split('\n')
+            # split each ref line into an array, drop non-origin branches
+            refs = [x.split() for x in refs if 'origin' in x]
+            binascii.unhexlify(refs[0][0])
+            return refs[0][0]
+        except morphlib.execute.CommandFailure:
+            if not self.is_valid_sha1(ref):
+                raise InvalidReferenceError(self, ref)
+            try:
+                binascii.unhexlify(ref)
+                return self._rev_list(ref)
+            except morphlib.execute.CommandFailure:
+                raise InvalidReferenceError(self, ref)
+
+    def cat(self, ref, filename):
+        if not self.is_valid_sha1(ref):
+            raise UnresolvedNamedReferenceError(self, ref)
+        try:
+            sha1 = self._rev_list(ref)
+            try:
+                return self._cat_file(sha1, filename)
+            except morphlib.execute.CommandFailure:
+                raise IOError('File %s does not exist in ref %s of repo %s' %
+                              (filename, ref, self))
+        except morphlib.execute.CommandFailure:
+            raise InvalidReferenceError(self, ref)
+
+    def checkout(self, ref, target_dir):
+        if not self.is_valid_sha1(ref):
+            raise UnresolvedNamedReferenceError(self, ref)
+
+        if os.path.exists(target_dir):
+            raise CheckoutDirectoryExistsError(self, target_dir)
+            
+        os.mkdir(target_dir)
+
+        try:
+            sha1 = self._rev_list(ref)
+            try:
+                self._copy_repository(self.path, target_dir)
+                self._checkout_ref(sha1, target_dir)
+            except morphlib.execute.CommandFailure:
+                raise CheckoutError(self, ref, target_dir)
+        except morphlib.execute.CommandFailure:
+            raise InvalidReferenceError(self, ref)
+
+    def update(self):
+        try:
+            self._update()
+        except morphlib.execute.CommandFailure:
+            raise UpdateError(self)
+
+    def _show_ref(self, ref): # pragma: no cover
+        return self.ex.runv(['git', 'show-ref', ref])
+
+    def _rev_list(self, ref): # pragma: no cover
+        return self.ex.runv(['git', 'rev-list', '--no-walk', ref])
+
+    def _cat_file(self, ref, filename): # pragma: no cover
+        return self.ex.runv(['git', 'cat-file', 'blob',
+                             '%s:%s' % (ref, filename)])
+
+    def _copy_repository(self, source_dir, target_dir): # pragma: no cover
+        self.ex.runv(['cp', '-a', os.path.join(source_dir, '.git'),
+                      target_dir])
+
+    def _checkout_ref(self, ref, target_dir): # pragma: no cover
+        self.ex.runv(['git', 'checkout', ref], pwd=target_dir)
+
+    def _update(self): # pragma: no cover
+        self.ex.runv(['git', 'remote', 'update', 'origin'])
+
+    def __str__(self): # pragma: no cover
+        return self.url
diff --git a/morphlib/cachedrepo_tests.py b/morphlib/cachedrepo_tests.py
new file mode 100644
index 00000000..79969a32
--- /dev/null
+++ b/morphlib/cachedrepo_tests.py
@@ -0,0 +1,181 @@
+# Copyright (C) 2012  Codethink Limited
+# 
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; version 2 of the License.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License along
+# with this program; if not, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+
+import os
+import unittest
+
+import morphlib
+
+from morphlib import cachedrepo
+
+
+class CachedRepoTests(unittest.TestCase):
+
+    def show_ref(self, ref):
+        output = {
+            'master': 
+                'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9'
+                ' refs/remotes/origin/master',
+            'baserock/morph':
+                '8b780e2e6f102fcf400ff973396566d36d730501'
+                ' refs/remotes/origin/baserock/morph',
+        }
+        try:
+            return output[ref]
+        except:
+            raise morphlib.execute.CommandFailure('git show-ref %s' % ref, '')
+
+    def rev_list(self, ref):
+        output = {
+            'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9': 
+                'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9',
+            'a4da32f5a81c8bc6d660404724cedc3bc0914a75':
+                'a4da32f5a81c8bc6d660404724cedc3bc0914a75'
+        }
+        try:
+            return output[ref]
+        except:
+            raise morphlib.execute.CommandFailure('git rev-list %s' % ref, '')
+
+    def cat_file(self, ref, filename):
+        output = {
+            'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9:foo.morph':
+                'contents of foo.morph'
+        }
+        try:
+            return output['%s:%s' % (ref, filename)]
+        except:
+            raise morphlib.execute.CommandFailure(
+                    'git cat-file blob %s:%s' % (ref, filename), '')
+
+    def copy_repository(self, source_dir, target_dir):
+        pass
+
+    def checkout_ref(self, ref, target_dir):
+        if ref == 'a4da32f5a81c8bc6d660404724cedc3bc0914a75':
+            # simulate a git failure or something similar to
+            # trigger a CheckoutError
+            raise morphlib.execute.CommandFailure('git checkout %s' % ref, '')
+        else:
+            with open(os.path.join(target_dir, 'foo.morph'), 'w') as f:
+                f.write('contents of foo.morph')
+
+    def update_successfully(self):
+        pass
+
+    def update_with_failure(self):
+        raise morphlib.execute.CommandFailure('git remote update origin', '')
+
+    def setUp(self):
+        self.repo_url = 'git://foo.bar/foo.git'
+        self.repo_path = '/tmp/foo'
+        self.repo = cachedrepo.CachedRepo(self.repo_url, self.repo_path)
+        self.repo._show_ref = self.show_ref
+        self.repo._rev_list = self.rev_list
+        self.repo._cat_file = self.cat_file
+        self.repo._copy_repository = self.copy_repository
+        self.repo._checkout_ref = self.checkout_ref
+        self.tempdir = morphlib.tempdir.Tempdir()
+
+    def tearDown(self):
+        self.tempdir.remove()
+
+    def test_constructor_sets_url_and_path(self):
+        self.assertEqual(self.repo.url, self.repo_url)
+        self.assertEqual(self.repo.path, self.repo_path)
+
+    def test_resolve_named_ref_master(self):
+        sha1 = self.repo.resolve_ref('master')
+        self.assertEqual(sha1, 'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9')
+
+    def test_resolve_named_ref_baserock_morph(self):
+        sha1 = self.repo.resolve_ref('baserock/morph')
+        self.assertEqual(sha1, '8b780e2e6f102fcf400ff973396566d36d730501')
+
+    def test_fail_resolving_invalid_named_ref(self):
+        with self.assertRaises(cachedrepo.InvalidReferenceError):
+            self.repo.resolve_ref('foo/bar')
+
+    def test_resolve_sha1_ref(self):
+        sha1 = self.repo.resolve_ref(
+                'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9')
+        self.assertEqual(sha1, 'e28a23812eadf2fce6583b8819b9c5dbd36b9fb9')
+
+    def test_fail_resolving_an_invalid_sha1_ref(self):
+        with self.assertRaises(cachedrepo.InvalidReferenceError):
+            self.repo.resolve_ref('079bbfd447c8534e464ce5d40b80114c2022ebf4')
+
+    def test_cat_existing_file_in_existing_ref(self):
+        data = self.repo.cat('e28a23812eadf2fce6583b8819b9c5dbd36b9fb9',
+                             'foo.morph')
+        self.assertEqual(data, 'contents of foo.morph')
+
+    def test_fail_cat_file_in_invalid_ref(self):
+        with self.assertRaises(cachedrepo.InvalidReferenceError):
+            self.repo.cat('079bbfd447c8534e464ce5d40b80114c2022ebf4',
+                          'doesnt-matter-whether-this-file-exists')
+
+    def test_fail_cat_non_existent_file_in_existing_ref(self):
+        with self.assertRaises(IOError):
+            self.repo.cat('e28a23812eadf2fce6583b8819b9c5dbd36b9fb9',
+                          'file-that-does-not-exist')
+
+    def test_fail_cat_non_existent_file_in_invalid_ref(self):
+        with self.assertRaises(cachedrepo.InvalidReferenceError):
+            self.repo.cat('079bbfd447c8534e464ce5d40b80114c2022ebf4',
+                          'file-that-does-not-exist')
+
+    def test_fail_because_cat_in_named_ref_is_not_allowed(self):
+        with self.assertRaises(cachedrepo.UnresolvedNamedReferenceError):
+            self.repo.cat('master', 'doesnt-matter-wether-this-file-exists')
+
+    def test_fail_checkout_into_existing_directory(self):
+        with self.assertRaises(cachedrepo.CheckoutDirectoryExistsError):
+            self.repo.checkout('e28a23812eadf2fce6583b8819b9c5dbd36b9fb9',
+                               self.tempdir.dirname)
+
+    def test_fail_checkout_from_named_ref_which_is_not_allowed(self):
+        with self.assertRaises(cachedrepo.UnresolvedNamedReferenceError):
+            self.repo.checkout('master',
+                               self.tempdir.join('checkout-from-named-ref'))
+
+    def test_fail_checkout_from_invalid_ref(self):
+        with self.assertRaises(cachedrepo.InvalidReferenceError):
+            self.repo.checkout('079bbfd447c8534e464ce5d40b80114c2022ebf4',
+                               self.tempdir.join('checkout-from-invalid-ref'))
+
+    def test_checkout_from_existing_ref_into_new_directory(self):
+        unpack_dir = self.tempdir.join('unpack-dir')
+        self.repo.checkout('e28a23812eadf2fce6583b8819b9c5dbd36b9fb9',
+                           unpack_dir)
+        self.assertTrue(os.path.exists(unpack_dir))
+
+        morph_filename = os.path.join(unpack_dir, 'foo.morph')
+        self.assertTrue(os.path.exists(morph_filename))
+
+    def test_fail_checkout_due_to_copy_or_checkout_problem(self):
+        with self.assertRaises(cachedrepo.CheckoutError):
+            self.repo.checkout('a4da32f5a81c8bc6d660404724cedc3bc0914a75',
+                               self.tempdir.join('failed-checkout'))
+
+    def test_successful_update(self):
+        self.repo._update = self.update_successfully
+        self.repo.update()
+
+    def test_failing_update(self):
+        self.repo._update = self.update_with_failure
+        with self.assertRaises(cachedrepo.UpdateError):
+            self.repo.update()