File-cache
==========

Enable disk-caching for the duration of this test.

  >>> class cache_enabler:
  ...     def __init__(self):
  ...         from chameleon.core import config
  ...         self.config = config
  ...         self.old_setting = config.DISK_CACHE
  ...         config.DISK_CACHE = True
  ...
  ...     def __del__(self):
  ...         self.config.DISK_CACHE = self.old_setting

  >>> _ = cache_enabler()

Write a template string to a temporary named file.
  
  >>> body = """\
  ... <div xmlns="http://www.w3.org/1999/xhtml">
  ...   Hello World!
  ... </div>"""

  >>> from tempfile import NamedTemporaryFile
  >>> f = NamedTemporaryFile('w')
  >>> f.write(body)
  >>> f.seek(0)
  
Instantiate template from file.

  >>> from chameleon.core.template import TemplateFile
  >>> from chameleon.core.testing import mock_parser
  >>> template = TemplateFile(f.name, mock_parser)

Verify that the disk-cache is enabled for this file.
  
  >>> template.registry
  <chameleon.core.filecache.TemplateCache object at ...>

Upon first rendering, the cache is written to.

  >>> print template()
  <div xmlns="http://www.w3.org/1999/xhtml">
    Hello World!
  </div>

  >>> len(template.registry)
  1
  
Verify that the registry can be restored.

  >>> template.registry.clear()
  >>> template.registry.load()
  >>> len(template.registry)
  1

Truncate the cache file and recover automatically.

  >>> template.registry.purge()
  >>> template.registry.load()
  >>> len(template.registry)
  0

Cleanup
-------
  
Close temporary file.
  
  >>> f.close()