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尝试围绕执行map_async()操作的函数编写一些单元测试。更具体地说，我想确认如果其中一个进程发生异常，某些文件会被清理。示例伪代码，其意图如下。

foo.py

def write_chunk(chunk):
    ... create file from chunk
    return created_filename

class Foo:
    def write_parallel(chunks):
        filenames = set()
        try:
            pool = Pool(processes=2)
            pool.map_async(write_chunk, chunks, callback=filenames.add)
        except Exception:
            //handle exception
        finally:
            cleanup_files(filenames)

test_foo.py

@patch("foo.write_chunk")
def test_write_parallel_exception_cleanup(self, mock_write_chunk):
    def mock_side_effect(chunk):
        if "chunk_1" == chunk:
            raise Exception
        else:
            return chunk
    mock_write_chunk.side_effect = mock_side_effect

    foo = Foo()
    foo.write_parallel({"chunk_1", "chunk_2"})
    //assert "chunk_2" cleaned up and exception is thrown.

但是，当我去执行测试时，我得到以下 PicklingError: PicklingError: Can't pickle <class 'mock.MagicMock'>: it's not the same object as mock.MagicMock。

任何想法如何执行用我自己的模拟函数替换映射函数的预期结果？

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1 回答 1

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因此，由于问题源于尝试对函数进行模拟和腌制，我决定将功能提取到一个单独的函数中，模拟该函数，同时允许对原始函数进行腌制。见下文：

foo.py

def write_chunk(chunk):
    return write_chunk_wrapped(chunk)

def write_chunk_wrapped(chunk)
    ... create file from chunk
    return created_filename

class Foo:
    def write_parallel(chunks):
        filenames = set()
        try:
            pool = Pool(processes=2)
            pool.map_async(write_chunk, chunks, callback=filenames.add)
        except Exception:
            //handle exception
        finally:
            cleanup_files(filenames)

test_foo.py

@patch("foo.write_chunk_wrapped")
def test_write_parallel_exception_cleanup(self, mock_write_chunk_wrapped):
    def mock_side_effect(chunk):
        if "chunk_1" == chunk:
            raise Exception
        else:
            return chunk
    mock_write_chunk_wrapped.side_effect = mock_side_effect

    foo = Foo()
    foo.write_parallel({"chunk_1", "chunk_2"})
    //assert "chunk_2" cleaned up and exception is thrown.
于 2015-11-10T02:14:51.307 回答