Can python doctest ignore some output lines?

With doctest.ELLIPSIS, you can use ... to mean "match any string here". You can set doctest options with a doctest directive, to make it active for just one test case: one example in the online docs is:

>>> print range(20) # doctest:+ELLIPSIS[0, 1, ..., 18, 19]

If you want a doctest option to be active throughout, you can pass it as the optionflags= argument to whatever doctest functions you use, e.g. doctest.testfile. (You can pass multiple option flags there by using the | operator to bit-or them).

Responding to questions about "how can we ignore the whole line": yes, the fact that "..." also looks like a continuation like makes it hard to ignore the entire output. You can use "#doctest: +SKIP" if you just want to skip the example entirely, but that won't work if you are relying on its side-effects. If you really need to do this, I suppose you could monkey-patch the doctest module itself, though I wouldn't particularly recommend it:

>>> import doctest>>> doctest.ELLIPSIS_MARKER = '-etc-'>>> print 12 # doctest: +ELLIPSIS-etc-

(this test passes.)

Or you could temporarily suppress stdout and/or stderr:

>>> # Suppress stdout>>> import sys>>> class DevNull:...     def noop(*args, **kwargs): pass...     close = write = flush = writelines = noop>>> sys.stdout = DevNull()>>> # Run a test and ignore output (but we need its side effects)>>> print 12 # NOTE: stdout is suppressed!>>> # Restore stdout>>> sys.stdout = sys.__stdout__

(this test also passes.)

Ignoring the whole line is bit tricky though. Here:

""">>> do_your_thing() #doctest:+ELLIPSIS..."""

The triple dot will be interpreted as line continuation, and cause a syntax error.

If you want to ignore the whole line, you'll need something like:

""">>> sys.stdout.write('skip from here '); do_your_thing() #doctest:+ELLIPSISskip from here ..."""