模拟 Python 的内置打印功能
问题描述
我试过了
from mock import Mock
import __builtin__
__builtin__.print = Mock()
但这会引发语法错误.我也试过这样修补它
But that raises a syntax error. I've also tried patching it like so
@patch('__builtin__.print')
def test_something_that_performs_lots_of_prints(self, mock_print):
# assert stuff
有没有办法做到这一点?
Is there any way to do this?
解决方案
print 是 python 2.x 中的关键字，将其用作属性会引发 SyntaxError.您可以通过在文件开头使用 from __future__ import print_function 来避免这种情况.
print is a keyword in python 2.x, using it as attribute raises a SyntaxError. You can avoid that by using from __future__ import print_function in the beginning of the file.
注意:你不能简单地使用 setattr，因为你修改的打印函数不会被调用，除非 print 语句被禁用.
Note: you can't simply use setattr, because the print function you modified doesn't get invoked unless the print statement is disabled.
您还需要 from __future__ import print_function 在您希望使用修改后的 print 函数的每个文件中，否则它将被 打印语句.
you also need to from __future__ import print_function in every file you want your modified print function to be used, or it will be masked by the print statement.
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