test_magic_folder.py

import os, sys

from twisted.trial import unittest
from twisted.internet import defer, task

from allmydata.interfaces import IDirectoryNode

from allmydata.util import fake_inotify, fileutil
from allmydata.util.deferredutil import DeferredListShouldSucceed
from allmydata.util.encodingutil import get_filesystem_encoding, to_filepath
from allmydata.util.consumer import download_to_data
from allmydata.test.no_network import GridTestMixin
from allmydata.test.common_util import ReallyEqualMixin, NonASCIIPathMixin
from allmydata.test.common import ShouldFailMixin
from .test_cli_magic_folder import MagicFolderCLITestMixin

from allmydata.frontends import magic_folder
from allmydata.frontends.magic_folder import MagicFolder, Downloader, WriteFileMixin
from allmydata import magicfolderdb, magicpath
from allmydata.util.fileutil import abspath_expanduser_unicode


class MagicFolderTestMixin(MagicFolderCLITestMixin, ShouldFailMixin, ReallyEqualMixin, NonASCIIPathMixin):
    """
    These tests will be run both with a mock notifier, and (on platforms that support it)
    with the real INotify.
    """

    def setUp(self):
        GridTestMixin.setUp(self)
        temp = self.mktemp()
        self.basedir = abspath_expanduser_unicode(temp.decode(get_filesystem_encoding()))
        self.magicfolder = None
        self.patch(Downloader, 'REMOTE_SCAN_INTERVAL', 0)

    def _get_count(self, name, client=None):
        counters = (client or self.get_client()).stats_provider.get_stats()["counters"]
        return counters.get('magic_folder.%s' % (name,), 0)

    def _createdb(self):
        dbfile = abspath_expanduser_unicode(u"magicfolderdb.sqlite", base=self.basedir)
        mdb = magicfolderdb.get_magicfolderdb(dbfile, create_version=(magicfolderdb.SCHEMA_v1, 1))
        self.failUnless(mdb, "unable to create magicfolderdb from %r" % (dbfile,))
        self.failUnlessEqual(mdb.VERSION, 1)
        return mdb

    def _restart_client(self, ign):
        #print "_restart_client"
        d = self.restart_client()
        d.addCallback(self._wait_until_started)
        return d

    def _wait_until_started(self, ign):
        #print "_wait_until_started"
        self.magicfolder = self.get_client().getServiceNamed('magic-folder')
        return self.magicfolder.ready()

    def test_db_basic(self):
        fileutil.make_dirs(self.basedir)
        self._createdb()

    def test_db_persistence(self):
        """Test that a file upload creates an entry in the database."""

        fileutil.make_dirs(self.basedir)
        db = self._createdb()


        relpath1 = u"myFile1"
        pathinfo = fileutil.PathInfo(isdir=False, isfile=True, islink=False,
                                     exists=True, size=1, mtime=123, ctime=456)
        db.did_upload_version(relpath1, 0, 'URI:LIT:1', 'URI:LIT:0', 0, pathinfo)

        c = db.cursor
        c.execute("SELECT size, mtime, ctime"
                  " FROM local_files"
                  " WHERE path=?",
                  (relpath1,))
        row = c.fetchone()
        self.failUnlessEqual(row, (pathinfo.size, pathinfo.mtime, pathinfo.ctime))

        # Second test uses db.is_new_file instead of SQL query directly
        # to confirm the previous upload entry in the db.
        relpath2 = u"myFile2"
        path2 = os.path.join(self.basedir, relpath2)
        fileutil.write(path2, "meow\n")
        pathinfo = fileutil.get_pathinfo(path2)
        db.did_upload_version(relpath2, 0, 'URI:LIT:2', 'URI:LIT:1', 0, pathinfo)
        self.failUnlessFalse(db.is_new_file(pathinfo, relpath2))

        different_pathinfo = fileutil.PathInfo(isdir=False, isfile=True, islink=False,
                                               exists=True, size=0, mtime=pathinfo.mtime, ctime=pathinfo.ctime)
        self.failUnlessTrue(db.is_new_file(different_pathinfo, relpath2))

    def test_magicfolder_start_service(self):
        self.set_up_grid()

        self.local_dir = abspath_expanduser_unicode(self.unicode_or_fallback(u"l\u00F8cal_dir", u"local_dir"),
                                                    base=self.basedir)
        self.mkdir_nonascii(self.local_dir)

        d = defer.succeed(None)
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.dirs_monitored'), 0))

        d.addCallback(lambda ign: self.create_invite_join_magic_folder(u"Alice", self.local_dir))
        d.addCallback(self._restart_client)

        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.dirs_monitored'), 1))
        d.addBoth(self.cleanup)
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.dirs_monitored'), 0))
        return d

    def test_move_tree(self):
        self.set_up_grid()

        self.local_dir = abspath_expanduser_unicode(self.unicode_or_fallback(u"l\u00F8cal_dir", u"local_dir"),
                                                    base=self.basedir)
        self.mkdir_nonascii(self.local_dir)

        empty_tree_name = self.unicode_or_fallback(u"empty_tr\u00EAe", u"empty_tree")
        empty_tree_dir = abspath_expanduser_unicode(empty_tree_name, base=self.basedir)
        new_empty_tree_dir = abspath_expanduser_unicode(empty_tree_name, base=self.local_dir)

        small_tree_name = self.unicode_or_fallback(u"small_tr\u00EAe", u"empty_tree")
        small_tree_dir = abspath_expanduser_unicode(small_tree_name, base=self.basedir)
        new_small_tree_dir = abspath_expanduser_unicode(small_tree_name, base=self.local_dir)

        d = self.create_invite_join_magic_folder(u"Alice", self.local_dir)
        d.addCallback(self._restart_client)

        def _check_move_empty_tree(res):
            print "_check_move_empty_tree"
            downloaded_d = self.magicfolder.downloader.set_hook('processed')
            uploaded_d = self.magicfolder.uploader.set_hook('processed')
            self.mkdir_nonascii(empty_tree_dir)
            os.rename(empty_tree_dir, new_empty_tree_dir)
            self.notify(to_filepath(new_empty_tree_dir), self.inotify.IN_MOVED_TO)

            return DeferredListShouldSucceed([downloaded_d, uploaded_d])
        d.addCallback(_check_move_empty_tree)
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 1))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.files_uploaded'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.directories_created'), 1))

        # FIXME check that Bob downloaded/created the empty tree.

        def _check_move_small_tree(res):
            print "_check_move_small_tree"
            downloaded_d = self.magicfolder.downloader.set_hook('processed', ignore_count=1)
            uploaded_d = self.magicfolder.uploader.set_hook('processed', ignore_count=1)
            self.mkdir_nonascii(small_tree_dir)
            fileutil.write(abspath_expanduser_unicode(u"what", base=small_tree_dir), "say when")
            os.rename(small_tree_dir, new_small_tree_dir)
            self.notify(to_filepath(new_small_tree_dir), self.inotify.IN_MOVED_TO)

            return DeferredListShouldSucceed([downloaded_d, uploaded_d])
        d.addCallback(_check_move_small_tree)
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 3))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.files_uploaded'), 1))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.directories_created'), 2))

        def _check_moved_tree_is_watched(res):
            print "_check_moved_tree_is_watched"
            downloaded_d = self.magicfolder.downloader.set_hook('processed', ignore_count=1)
            uploaded_d = self.magicfolder.uploader.set_hook('processed')
            fileutil.write(abspath_expanduser_unicode(u"another", base=new_small_tree_dir), "file")
            self.notify(to_filepath(abspath_expanduser_unicode(u"another", base=new_small_tree_dir)), self.inotify.IN_CLOSE_WRITE)

            return DeferredListShouldSucceed([downloaded_d, uploaded_d])
        d.addCallback(_check_moved_tree_is_watched)
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 4))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.files_uploaded'), 2))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.directories_created'), 2))

        # Files that are moved out of the upload directory should no longer be watched.
        #def _move_dir_away(ign):
        #    os.rename(new_empty_tree_dir, empty_tree_dir)
        #    # Wuh? Why don't we get this event for the real test?
        #    #self.notify(to_filepath(new_empty_tree_dir), self.inotify.IN_MOVED_FROM)
        #d.addCallback(_move_dir_away)
        #def create_file(val):
        #    test_file = abspath_expanduser_unicode(u"what", base=empty_tree_dir)
        #    fileutil.write(test_file, "meow")
        #    #self.notify(...)
        #    return
        #d.addCallback(create_file)
        #d.addCallback(lambda ign: time.sleep(1))  # XXX ICK
        #d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        #d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 4))
        #d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.files_uploaded'), 2))
        #d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        #d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.directories_created'), 2))

        d.addBoth(self.cleanup)
        return d

    def test_persistence(self):
        """
        Perform an upload of a given file and then stop the client.
        Start a new client and magic-folder service... and verify that the file is NOT uploaded
        a second time. This test is meant to test the database persistence along with
        the startup and shutdown code paths of the magic-folder service.
        """
        self.set_up_grid()
        self.local_dir = abspath_expanduser_unicode(u"test_persistence", base=self.basedir)
        self.mkdir_nonascii(self.local_dir)
        self.collective_dircap = ""

        d = defer.succeed(None)
        d.addCallback(lambda ign: self.create_invite_join_magic_folder(u"Alice", self.local_dir))
        d.addCallback(self._restart_client)

        def create_test_file(filename):
            d2 = self.magicfolder.uploader.set_hook('processed')
            test_file = abspath_expanduser_unicode(filename, base=self.local_dir)
            fileutil.write(test_file, "meow %s" % filename)
            self.notify(to_filepath(test_file), self.inotify.IN_CLOSE_WRITE)
            return d2
        d.addCallback(lambda ign: create_test_file(u"what1"))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 1))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        d.addCallback(self.cleanup)

        d.addCallback(self._restart_client)
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 1))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        d.addCallback(lambda ign: create_test_file(u"what2"))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'), 2))
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        d.addBoth(self.cleanup)
        return d

    def test_magic_folder(self):
        self.set_up_grid()
        self.local_dir = os.path.join(self.basedir, self.unicode_or_fallback(u"loc\u0101l_dir", u"local_dir"))
        self.mkdir_nonascii(self.local_dir)

        d = self.create_invite_join_magic_folder(u"Alice\u0101", self.local_dir)
        d.addCallback(self._restart_client)

        # Write something short enough for a LIT file.
        d.addCallback(lambda ign: self._check_file(u"short", "test"))

        # Write to the same file again with different data.
        d.addCallback(lambda ign: self._check_file(u"short", "different"))

        # Test that temporary files are not uploaded.
        d.addCallback(lambda ign: self._check_file(u"tempfile", "test", temporary=True))

        # Test that we tolerate creation of a subdirectory.
        d.addCallback(lambda ign: os.mkdir(os.path.join(self.local_dir, u"directory")))

        # Write something longer, and also try to test a Unicode name if the fs can represent it.
        name_u = self.unicode_or_fallback(u"l\u00F8ng", u"long")
        d.addCallback(lambda ign: self._check_file(name_u, "test"*100))

        # TODO: test that causes an upload failure.
        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))

        d.addBoth(self.cleanup)
        return d

    def _check_file(self, name_u, data, temporary=False):
        previously_uploaded = self._get_count('uploader.objects_succeeded')
        previously_disappeared = self._get_count('uploader.objects_disappeared')

        d = self.magicfolder.uploader.set_hook('processed')

        path_u = abspath_expanduser_unicode(name_u, base=self.local_dir)
        path = to_filepath(path_u)

        # We don't use FilePath.setContent() here because it creates a temporary file that
        # is renamed into place, which causes events that the test is not expecting.
        f = open(path_u, "wb")
        try:
            if temporary and sys.platform != "win32":
                os.unlink(path_u)
            f.write(data)
        finally:
            f.close()
        if temporary and sys.platform == "win32":
            os.unlink(path_u)
            self.notify(path, self.inotify.IN_DELETE)
        fileutil.flush_volume(path_u)
        self.notify(path, self.inotify.IN_CLOSE_WRITE)

        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_failed'), 0))
        if temporary:
            d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_disappeared'),
                                                                 previously_disappeared + 1))
        else:
            d.addCallback(lambda ign: self.upload_dirnode.get(name_u))
            d.addCallback(download_to_data)
            d.addCallback(lambda actual_data: self.failUnlessReallyEqual(actual_data, data))
            d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_succeeded'),
                                                                 previously_uploaded + 1))

        d.addCallback(lambda ign: self.failUnlessReallyEqual(self._get_count('uploader.objects_queued'), 0))
        return d

    def _check_version_in_dmd(self, magicfolder, relpath_u, expected_version):
        encoded_name_u = magicpath.path2magic(relpath_u)
        d = magicfolder.downloader._get_collective_latest_file(encoded_name_u)
        def check_latest(result):
            if result[0] is not None:
                node, metadata = result
                d.addCallback(lambda ign: self.failUnlessEqual(metadata['version'], expected_version))
        d.addCallback(check_latest)
        return d

    def _check_version_in_local_db(self, magicfolder, relpath_u, expected_version):
        version = magicfolder._db.get_local_file_version(relpath_u)
        #print "_check_version_in_local_db: %r has version %s" % (relpath_u, version)
        self.failUnlessEqual(version, expected_version)

    def test_alice_bob(self):
        alice_clock = task.Clock()
        bob_clock = task.Clock()
        d = self.setup_alice_and_bob(alice_clock, bob_clock)
        def get_results(result):
            # XXX are these used?
            (self.alice_collective_dircap, self.alice_upload_dircap, self.alice_magicfolder,
             self.bob_collective_dircap,   self.bob_upload_dircap,   self.bob_magicfolder) = result
            #print "Alice magicfolderdb is at %r" % (self.alice_magicfolder._client.basedir)
            #print "Bob   magicfolderdb is at %r" % (self.bob_magicfolder._client.basedir)
        d.addCallback(get_results)

        def _check_uploader_count(ign, name, expected):
            self.failUnlessReallyEqual(self._get_count('uploader.'+name, client=self.alice_magicfolder._client),
                                       expected)
        def _check_downloader_count(ign, name, expected):
            self.failUnlessReallyEqual(self._get_count('downloader.'+name, client=self.bob_magicfolder._client),
                                       expected)

        def _wait_for(ign, something_to_do):
            downloaded_d = self.bob_magicfolder.downloader.set_hook('processed')
            uploaded_d = self.alice_magicfolder.uploader.set_hook('processed')
            something_to_do()
            print "Waiting for Alice to upload\n"
            alice_clock.advance(0)
            def _wait_for_Bob(ign):
                print "Now waiting for Bob to download\n"
                bob_clock.advance(0)
                return downloaded_d
            uploaded_d.addCallback(_wait_for_Bob)
            return uploaded_d

        def Alice_to_write_a_file():
            print "Alice writes a file\n"
            self.file_path = abspath_expanduser_unicode(u"file1", base=self.alice_magicfolder.uploader._local_path_u)
            fileutil.write(self.file_path, "meow, meow meow. meow? meow meow! meow.")
            self.magicfolder = self.alice_magicfolder
            self.notify(to_filepath(self.file_path), self.inotify.IN_CLOSE_WRITE)
        d.addCallback(_wait_for, Alice_to_write_a_file)

        d.addCallback(lambda ign: self._check_version_in_dmd(self.alice_magicfolder, u"file1", 0))
        d.addCallback(lambda ign: self._check_version_in_local_db(self.alice_magicfolder, u"file1", 0))
        d.addCallback(_check_uploader_count, 'objects_failed', 0)
        d.addCallback(_check_uploader_count, 'objects_succeeded', 1)
        d.addCallback(_check_uploader_count, 'files_uploaded', 1)
        d.addCallback(_check_uploader_count, 'objects_queued', 0)
        d.addCallback(_check_uploader_count, 'directories_created', 0)

        d.addCallback(lambda ign: self._check_version_in_local_db(self.bob_magicfolder, u"file1", 0))
        d.addCallback(_check_downloader_count, 'objects_failed', 0)
        d.addCallback(_check_downloader_count, 'objects_downloaded', 1)

        def Alice_to_delete_file():
            print "Alice deletes the file!\n"
            os.unlink(self.file_path)
            self.magicfolder = self.alice_magicfolder
            self.notify(to_filepath(self.file_path), self.inotify.IN_DELETE)
        d.addCallback(_wait_for, Alice_to_delete_file)

        d.addCallback(lambda ign: self._check_version_in_dmd(self.alice_magicfolder, u"file1", 1))
        d.addCallback(lambda ign: self._check_version_in_local_db(self.alice_magicfolder, u"file1", 1))
        d.addCallback(_check_uploader_count, 'objects_failed', 0)
        d.addCallback(_check_uploader_count, 'objects_succeeded', 2)

        d.addCallback(lambda ign: self._check_version_in_local_db(self.bob_magicfolder, u"file1", 1))
        d.addCallback(lambda ign: self._check_version_in_dmd(self.bob_magicfolder, u"file1", 1))
        d.addCallback(_check_downloader_count, 'objects_failed', 0)
        d.addCallback(_check_downloader_count, 'objects_downloaded', 2)

        def Alice_to_rewrite_file():
            print "Alice rewrites file\n"
            self.file_path = abspath_expanduser_unicode(u"file1", base=self.alice_magicfolder.uploader._local_path_u)
            fileutil.write(self.file_path, "Alice suddenly sees the white rabbit running into the forest.")
            self.notify(to_filepath(self.file_path), self.inotify.IN_CLOSE_WRITE)
        d.addCallback(_wait_for, Alice_to_rewrite_file)

        d.addCallback(lambda ign: self._check_version_in_dmd(self.alice_magicfolder, u"file1", 2))
        d.addCallback(lambda ign: self._check_version_in_local_db(self.alice_magicfolder, u"file1", 2))
        d.addCallback(_check_uploader_count, 'objects_failed', 0)
        d.addCallback(_check_uploader_count, 'objects_succeeded', 3)
        d.addCallback(_check_uploader_count, 'files_uploaded', 3)
        d.addCallback(_check_uploader_count, 'objects_queued', 0)
        d.addCallback(_check_uploader_count, 'directories_created', 0)

        d.addCallback(lambda ign: self._check_version_in_dmd(self.bob_magicfolder, u"file1", 2))
        d.addCallback(lambda ign: self._check_version_in_local_db(self.bob_magicfolder, u"file1", 2))
        d.addCallback(_check_downloader_count, 'objects_failed', 0)
        d.addCallback(_check_downloader_count, 'objects_downloaded', 3)

        def _cleanup(ign, magicfolder, clock):
            d2 = magicfolder.finish()
            clock.advance(0)
            return d2

        def cleanup_Alice_and_Bob(result):
            print "cleanup alice bob test\n"
            d = defer.succeed(None)
            d.addCallback(_cleanup, self.alice_magicfolder, alice_clock)
            d.addCallback(_cleanup, self.bob_magicfolder, bob_clock)
            d.addCallback(lambda ign: result)
            return d
        d.addBoth(cleanup_Alice_and_Bob)
        return d


class MockTest(MagicFolderTestMixin, unittest.TestCase):
    """This can run on any platform, and even if twisted.internet.inotify can't be imported."""

    def setUp(self):
        MagicFolderTestMixin.setUp(self)
        self.inotify = fake_inotify
        self.patch(magic_folder, 'get_inotify_module', lambda: self.inotify)

    def notify(self, path, mask):
        self.magicfolder.uploader._notifier.event(path, mask)

    def test_errors(self):
        self.set_up_grid()

        errors_dir = abspath_expanduser_unicode(u"errors_dir", base=self.basedir)
        os.mkdir(errors_dir)
        not_a_dir = abspath_expanduser_unicode(u"NOT_A_DIR", base=self.basedir)
        fileutil.write(not_a_dir, "")
        magicfolderdb = abspath_expanduser_unicode(u"magicfolderdb", base=self.basedir)
        doesnotexist  = abspath_expanduser_unicode(u"doesnotexist", base=self.basedir)

        client = self.g.clients[0]
        d = client.create_dirnode()
        def _check_errors(n):
            self.failUnless(IDirectoryNode.providedBy(n))
            upload_dircap = n.get_uri()
            readonly_dircap = n.get_readonly_uri()

            self.shouldFail(AssertionError, 'nonexistent local.directory', 'there is no directory',
                            MagicFolder, client, upload_dircap, '', doesnotexist, magicfolderdb)
            self.shouldFail(AssertionError, 'non-directory local.directory', 'is not a directory',
                            MagicFolder, client, upload_dircap, '', not_a_dir, magicfolderdb)
            self.shouldFail(AssertionError, 'bad upload.dircap', 'does not refer to a directory',
                            MagicFolder, client, 'bad', '', errors_dir, magicfolderdb)
            self.shouldFail(AssertionError, 'non-directory upload.dircap', 'does not refer to a directory',
                            MagicFolder, client, 'URI:LIT:foo', '', errors_dir, magicfolderdb)
            self.shouldFail(AssertionError, 'readonly upload.dircap', 'is not a writecap to a directory',
                            MagicFolder, client, readonly_dircap, '', errors_dir, magicfolderdb,)
            self.shouldFail(AssertionError, 'collective dircap',
                            "The URI in 'private/collective_dircap' is not a readonly cap to a directory.",
                            MagicFolder, client, upload_dircap, upload_dircap, errors_dir, magicfolderdb)

            def _not_implemented():
                raise NotImplementedError("blah")
            self.patch(magic_folder, 'get_inotify_module', _not_implemented)
            self.shouldFail(NotImplementedError, 'unsupported', 'blah',
                            MagicFolder, client, upload_dircap, '', errors_dir, magicfolderdb)
        d.addCallback(_check_errors)
        return d

    def test_write_downloaded_file(self):
        workdir = u"cli/MagicFolder/write-downloaded-file"
        local_file = fileutil.abspath_expanduser_unicode(os.path.join(workdir, "foobar"))

        class TestWriteFileMixin(WriteFileMixin):
            def _log(self, msg):
                pass

        writefile = TestWriteFileMixin()

        # create a file with name "foobar" with content "foo"
        # write downloaded file content "bar" into "foobar" with is_conflict = False
        fileutil.make_dirs(workdir)
        fileutil.write(local_file, "foo")

        # if is_conflict is False, then the .conflict file shouldn't exist.
        writefile._write_downloaded_file(local_file, "bar", False, None)
        conflicted_path = local_file + u".conflict"
        self.failIf(os.path.exists(conflicted_path))

        # At this point, the backup file should exist with content "foo"
        backup_path = local_file + u".backup"
        self.failUnless(os.path.exists(backup_path))
        self.failUnlessEqual(fileutil.read(backup_path), "foo")

        # .tmp file shouldn't exist
        self.failIf(os.path.exists(local_file + u".tmp"))

        # .. and the original file should have the new content
        self.failUnlessEqual(fileutil.read(local_file), "bar")

        # now a test for conflicted case
        writefile._write_downloaded_file(local_file, "bar", True, None)
        self.failUnless(os.path.exists(conflicted_path))

        # .tmp file shouldn't exist
        self.failIf(os.path.exists(local_file + u".tmp"))


class RealTest(MagicFolderTestMixin, unittest.TestCase):
    """This is skipped unless both Twisted and the platform support inotify."""

    def setUp(self):
        MagicFolderTestMixin.setUp(self)
        self.inotify = magic_folder.get_inotify_module()

    def notify(self, path, mask):
        # Writing to the filesystem causes the notification.
        pass

try:
    magic_folder.get_inotify_module()
except NotImplementedError:
    RealTest.skip = "Magic Folder support can only be tested for-real on an OS that supports inotify or equivalent."