Python 由于缺少模块，py.test失败

我想编写一个测试，但只有安装了

nlopt

模块，此测试才会通过。由于这个模块是可选的，我想知道是否有一种方法可以编写一个测试，如果模块不存在，它不会阻止py.test完全失败。此时，py.test停止，因为它找不到

nlopt

模块：

$ make test
py.test --exitfirst tests/
============================================================= test session starts =============================================================
platform darwin -- Python 3.4.2 -- py-1.4.26 -- pytest-2.6.4
collecting 0 items / 1 errors
=================================================================== ERRORS ====================================================================
_____________________________________________ ERROR collecting tests/unit/fem/test_simulation.py ______________________________________________
tests/unit/fem/test_simulation.py:5: in <module>
    from hybrida.fem import Simulation, Step, Eigenvalue
src/hybrida/__init__.py:4: in <module>
    from . import geometry
src/hybrida/geometry/__init__.py:3: in <module>
    from . import distance
src/hybrida/geometry/distance.py:9: in <module>
    import nlopt
E   ImportError: No module named 'nlopt'
--------------------------------------------------------------- Captured stdout ---------------------------------------------------------------
 nlopt does not seem to be installed. 
=========================================================== short test summary info ===========================================================
ERROR tests/unit/fem/test_simulation.py
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Interrupted: stopping after 1 failures !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
=========================================================== 1 error in 0.67 seconds ===========================================================
make: *** [test] Error 2

nlopt

模块在我正在编写测试的库中使用。当前，如果找不到模块，库将引发异常。在使用模块的文件的顶层：

try:
    import nlopt

except ImportError:
    print("""\033[91m nlopt does not seem to be installed. Please install it by downloading nlopt, and installing it using
        $ ./configure --enable-shared
        $ make
        $ make install
        and adding /usr/local/lib/Python3.4/site-packages to the PYTHONPATH
        (or wherever nlopt has been installed):
        export PYTHONPATH=$PYTHONPATH:/usr/local/lib/Python3.4/site-packages

        Note: although Homebrew provides nlopt, it does not install the Python interface.\033[0m""")
    raise

使用pytest提供的：

nlopt = pytest.importorskip('nlopt')

---

将该行放在使用

nlopt

（或一组函数的设置方法）的特定测试函数中，它只会在无法进行导入时跳过这些函数。

我尝试过，但代码在我提供测试的库中仍然失败，与库内部一样，还有一个

import nlopt

，如果它找不到模块，就会引发异常。您可以将该

import

移动到实际使用它的函数内部，而不是使其处于顶级。您是指库端还是测试端？在库端。当未找到

nlopt

时，库代码当前做什么？我修改了我的帖子，向您展示了库当前做什么。这看起来很难看，但我不知道有什么更好的方法来实现这一点。理想情况下，我希望库能够工作，即使计算机中没有安装模块。

nlopt = pytest.importorskip('nlopt')