'make_tmpfs_mount should create a tmpfs mountpoint that can be written
to. Once the mount is unmounted all files should be gone.'

def test_make_tmpfs_mount(self):

    mountpoint = self._get_directory_for_mount()
    test_file = mountpoint.child(unicode(uuid4()))
    self.manager_under_test.make_tmpfs_mount(mountpoint)
    self.expectThat(test_file.path, Not(FileExists()))
    test_file.touch()
    self.expectThat(test_file.path, FileExists(), 'File    did    not    exist    after    being    touched    on    tmpfs.')
    self.manager_under_test.unmount(mountpoint)
    self.expectThat(test_file.path, Not(FileExists()), 'File    persisted    after    tmpfs    mount    unmounted')
