Test suite fails when working offline

[mgorny]

When running the test suite on a firewalled environment without direct Internet connectivity, all tests fail with the same error, e.g.:

___________________________________________________________ test_glissando ____________________________________________________________

    def test_glissando():
>       compare_output('glissando')

tests/test_xml.py:16: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
tests/test_xml.py:109: in compare_output
    validate_xml(output)
tests/test_xml.py:118: in validate_xml
    xmlschema = etree.XMLSchema(xmlschema_doc)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

>   ???
E   lxml.etree.XMLSchemaParseError: attribute use (unknown), attribute 'ref': The QName value '{http://www.w3.org/XML/1998/namespace}lang' does not resolve to a(n) attribute declaration., line 1810

src/lxml/xmlschema.pxi:90: XMLSchemaParseError

[mgorny]

FWICS lxml has no caching either, so it refetches all the remote schema files every time. There's some discussion about the problem here: w3c/musicxml#445. Apparently, the simplest solution would be to include the other files in the distribution, and replace the URL references with local paths.