iptest.py 文件源码

def test_for(item, min_version=None, callback=extract_version):
    """Test to see if item is importable, and optionally check against a minimum
    version.

    If min_version is given, the default behavior is to check against the
    `__version__` attribute of the item, but specifying `callback` allows you to
    extract the value you are interested in. e.g::

        In [1]: import sys

        In [2]: from IPython.testing.iptest import test_for

        In [3]: test_for('sys', (2,6), callback=lambda sys: sys.version_info)
        Out[3]: True

    """
    try:
        check = import_item(item)
    except (ImportError, RuntimeError):
        # GTK reports Runtime error if it can't be initialized even if it's
        # importable.
        return False
    else:
        if min_version:
            if callback:
                # extra processing step to get version to compare
                check = callback(check)

            return check >= min_version
        else:
            return True

# Global dict where we can store information on what we have and what we don't
# have available at test run time