[英]How do I mock a file open for a specific path in python?
So I know that in my unit test I can mock a context manager open(), ie:所以我知道在我的单元测试中我可以模拟一个上下文管理器 open(),即:
with open('file_path', 'r') as stats:
mocked with嘲笑
with mock.patch('builtins.open', mock.mock_open(read_data=mock_json)):
but is there a way for me to only mock it for a specific file path?但是有没有办法让我只为特定的文件路径模拟它? Or maybe some other way to ensure that the context manager gets called with the correct path in a unit test?或者可能是其他方式来确保在单元测试中使用正确的路径调用上下文管理器?
To mock open
only for a specific path, you have to provide your own mock object that handles open
differently, depending on the path.要仅为特定路径模拟open
,您必须提供自己的模拟对象,根据路径以不同方式处理open
。 Assuming we have some function:假设我们有一些功能:
def do_open(path):
with open(path, "r") as f:
return f.read()
where open
shall be mocked to return a file with the content "bar" if path
is "foo", but otherwise just work as usual, you could do something like this:如果path
为“foo”,则应模拟open
以返回内容为“bar”的文件,否则照常工作,您可以执行以下操作:
from unittest import mock
from my_module.do_open import do_open
builtin_open = open # save the unpatched version
def mock_open(*args, **kwargs):
if args[0] == "foo":
# mocked open for path "foo"
return mock.mock_open(read_data="bar")(*args, **kwargs)
# unpatched version for every other path
return builtin_open(*args, **kwargs)
@mock.patch("builtins.open", mock_open)
def test_open():
assert do_open("foo") == "bar"
assert do_open(__file__) != "bar"
If you don't want to save the original open
in a global variable, you could also wrap that into a class:如果您不想将原始open
保存在全局变量中,也可以将其包装到一个类中:
class MockOpen:
builtin_open = open
def open(self, *args, **kwargs):
if args[0] == "foo":
return mock.mock_open(read_data="bar")(*args, **kwargs)
return self.builtin_open(*args, **kwargs)
@mock.patch("builtins.open", MockOpen().open)
def test_open():
...
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