本地导入点名包进行单元测试

Question

我正在尝试开发和测试一个包 foo.bar。我有以下目录布局：

myproject
  setup.py (for package foo.bar)
  foo
    bar
      __init__.py
      ...
  tests
    main.py
    test_something.py

在 test_something.py 中，我想导入 foo.bar 的本地副本，最好只使用 'import foo.bar'。

在 main.py 我有：

import os
import sys

sys.path.append(
    os.path.abspath(os.path.join(os.path.dirname(__file__), '..')))

import test_something

但是，我得到一个错误：

File "./tests/main.py", line 22, in <module>
  import test_something
File "/myproject/tests/test_something.py", line 28, in <module>
  import foo.bar
ImportError: No module named bar

可以这样做吗？

Answer 1

如果想让foo被认为是一个包，需要在foo目录下直接有一个__init__.py，可以为空，但是文件需要那里。否则 Python 不会将 foo 视为一个包，你不能做 -

import foo.bar

正如评论中所说 -

In any event I don't want foo to be a package, I want foo.bar to be the package.

这不是直接可能的，因为，除非 foo 是一个 Python 包（或下面解释的命名空间包），否则您不能执行 import foo.bar。

此处唯一的其他选择是使用 -

将 foo 文件夹直接添加到 sys.path

sys.path.append(
    os.path.abspath(os.path.join(os.path.dirname(__file__), '..', 'foo')))

然后您必须将其导入为 -

import bar

如果你使用的是 Python 3.3 + ，那么你可以使用 namespace packages ，并且你可以导入 foo.bar 而无需定义foo.

里面的 __init__.py

这在 - PEP 0420 中有很好的解释，根据规范，python packages/modules（从 3.3 + 开始）的新加载过程是 -

During import processing, the import machinery will continue to iterate over each directory in the parent path as it does in Python 3.2. While looking for a module or package named "foo", for each directory in the parent path:

If <directory>/foo/__init__.py is found, a regular package is imported and returned.

If not, but <directory>/foo.{py,pyc,so,pyd} is found, a module is imported and returned. The exact list of extension varies by platform and whether the -O flag is specified. The list here is representative.

If not, but <directory>/foo is found and is a directory, it is recorded and the scan continues with the next directory in the parent path.

Otherwise the scan continues with the next directory in the parent path.

If the scan completes without returning a module or package, and at least one directory was recorded, then a namespace package is created. The new namespace package:

Has a __path__ attribute set to an iterable of the path strings that were found and recorded during the scan.

Does not have a __file__ attribute.

本地导入点名包进行单元测试

Importing a dotted-name package locally for unit testing

python

python-import