How enable ellipsis when calling Python doctest?

Question

In Python (3.3.2) doctest, ellipsis (...) can match any string. So, for the code below

def foo():
    """
    >>> foo()
    hello ...
    """
    print("hello world")

when running doctest it shouldn't raise any error. But

$ python -m doctest foo.py 
**********************************************************************
File "./foo.py", line 3, in foo.foo
Failed example:
    foo()
Expected:
    hello ...
Got:
    hello world
**********************************************************************
1 items had failures:
   1 of   1 in foo.foo
***Test Failed*** 1 failures.

What I must do to enable the ellipis? As far as I can tell it is disable by default.

I know that add # doctest: +ELLIPSIS, as in the code below, solve it, but I like to enable ellipsis for all tests.

def foo():
    """
    >>> foo() # doctest: +ELLIPSIS
    hello ...
    """
    print("hello world")

Answer 1

You can pass in optionflags to the testmod method, but this requires you to run the module itself instead of the doctest module:

def foo():
    """
    >>> foo()
    hello ...
    """
    print("hello world")

if __name__ == "__main__":
    import doctest
    doctest.testmod(verbose=True, optionflags=doctest.ELLIPSIS)

Output:

$ python foo.py
Trying:
    foo()
Expecting:
    hello ...
ok
1 items had no tests:
    __main__
1 items passed all tests:
   1 tests in __main__.foo
1 tests in 2 items.
1 passed and 0 failed.
Test passed.