python doctest 可以忽略一些输出行吗？
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Can python doctest ignore some output lines?
提问by cjb
I'd like to write a doctest like this:
我想写一个这样的doctest：
"""
>>> print a.string()
foo : a
bar : b
date : <I don't care about the date output>
baz : c
"""
Is there any way to do this? I think it would make more sense to switch to unittest, but I'm curious whether it's possible to specify a range of output that shouldn't be matched for the test in doctest.
有没有办法做到这一点？我认为切换到 unittest 会更有意义，但我很好奇是否可以指定一个不应与 doctest 中的测试匹配的输出范围。
Thanks!
谢谢！
回答by Alex Martelli
With doctest.ELLIPSIS, you can use ...to mean "match any string here". You can set doctestoptions with a doctest directive, to make it active for just one test case: one example in the online docsis:
使用doctest.ELLIPSIS，您可以...表示“匹配此处的任何字符串”。您可以doctest使用 doctest 指令设置选项，使其仅对一个测试用例有效：在线文档中的一个示例是：
>>> 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).
如果您希望 doctest 选项始终处于活动状态，您可以将其作为optionflags=参数传递给您使用的任何 doctest 函数，例如doctest.testfile. （您可以通过使用|运算符对它们进行位或它们传递多个选项标志）。
回答by Edward Loper
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 reallyneed to do this, I suppose you could monkey-patch the doctest module itself, though I wouldn't particularly recommend it:
回答关于“我们如何忽略整行”的问题：是的，事实上“...”也看起来像一个延续，这使得很难忽略整个输出。如果您只想完全跳过该示例，可以使用 "#doctest: +SKIP"，但如果您依赖其副作用，这将不起作用。如果您真的需要这样做，我想您可以对 doctest 模块本身进行猴子补丁，尽管我不会特别推荐它：
>>> import doctest
>>> doctest.ELLIPSIS_MARKER = '-etc-'
>>> print 12 # doctest: +ELLIPSIS
-etc-
(this test passes.)
（此测试通过。）
Or you could temporarily suppress stdout and/or stderr:
或者您可以暂时取消 stdout 和/或 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.)
（这个测试也通过了。）
回答by Mark Horvath
Ignoring the whole line is bit tricky though. Here:
不过，忽略整条线有点棘手。这里：
"""
>>> do_your_thing() #doctest:+ELLIPSIS
...
"""
The triple dot will be interpreted as line continuation, and cause a syntax error.
三点将被解释为行继续，并导致语法错误。
If you want to ignore the whole line, you'll need something like:
如果你想忽略整行，你需要这样的东西：
"""
>>> sys.stdout.write('skip from here '); do_your_thing() #doctest:+ELLIPSIS
skip from here ...
"""
回答by WilliamMayor
I found it easier to simply assign the unneeded return values to a variable:
我发现将不需要的返回值简单地分配给变量更容易：
>>> _ = do_something()
>>> check_something()
True
回答by adalbertpl
You can write tuples before and after your function (hack inspired by answer of Mark Horvath):
您可以在函数之前和之后编写元组（受到 Mark Horvath 回答的启发）：
def foo():
"""
>>> ();foo();() # doctest: +ELLIPSIS
(...)
"""
print "Hello world"
return "Hello world"
回答by samwyse
Can I have an ellipsis at the beginning of the line in a Python doctest?explains how to create a custom output checker that uses an additional string as an ellipsis. This would let you write the following, while still used '...' elsewhere.
我可以在 Python doctest 的行首使用省略号吗？解释了如何创建使用附加字符串作为省略号的自定义输出检查器。这将使您可以编写以下内容，同时在其他地方仍然使用“...”。
def foo():
"""
>>> foo() # doctest: +ELLIPSIS
[...] world
"""
print "hello world"
