Python doctest example failure

This is probably a silly question.

I am experimenting with python doctest, and I try to run this example

ending with

if __name__ == "__main__":
    import doctest
    doctest.testfile("e开发者_开发知识库xample.txt")

I have put "example.txt" in the same folder as the source file containing the example code, but I get the following error:

Traceback (most recent call last):
File "test_av_funktioner.py", line 61, in <module>
doctest.testfile("example.txt")
File "C:\Python26\lib\doctest.py", line 1947, in testfile
text, filename = _load_testfile(filename, package, module_relative)
File "C:\Python26\lib\doctest.py", line 219, in _load_testfile
return open(filename).read(), filename
IOError: [Errno 2] No such file or directory: 'example.txt'

Can I somehow tell/set where the doctest module is searching for the specified file?

Doctest searches relative to the calling module's directory by default (but you can override this).

Quoting the docs for doctest.testfile:

Optional argument module_relative specifies how the filename should be interpreted:

• If module_relative is True (the default), then filename specifies an OS-independent module-relative path. By default, this path is relative to the calling module’s directory; but if the package argument is specified, then it is relative to that package. To ensure OS-independence, filename should use / characters to separate path segments, and may not be an absolute path (i.e., it may not begin with /).
• If module_relative is False, then filename specifies an OS-specific path. The path may be absolute or relative; relative paths are resolved with respect to the current working directory.