working directory).

package
  A Python package or the name of a Python package whose directory
  should be used as the base directory for module relative paths.
  If "package" is not specified, then the calling module's
  directory is used as the base directory for module relative
  filenames.  It is an error to specify "package" if
  "module_relative" is False.

setUp
  A set-up function.  This is called before running the
  tests in each file. The setUp function will be passed a DocTest
  object.  The setUp function can access the test globals as the
  globs attribute of the test passed.

tearDown
  A tear-down function.  This is called after running the
  tests in each file.  The tearDown function will be passed a DocTest
  object.  The tearDown function can access the test globals as the
  globs attribute of the test passed.

globs
  A dictionary containing initial global variables for the tests.

optionflags
  A set of doctest option flags expressed as an integer.

parser
  A DocTestParser (or subclass) that should be used to extract
  tests from the files.

encoding
  An encoding that will be used to convert the files to unicode.
r`