def cpython(fn):
    return _chain_decorators_on(
         fn,
         skip_if(lambda: util.jython or util.pypy, 
           "cPython interpreter needed"
         )
    )

def denormalized_names(fn):
    """Target database must have 'denormalized', i.e. UPPERCASE as case insensitive names."""

    return skip_if(
                lambda: not testing.db.dialect.requires_name_normalize,
                "Backend does not require denomralized names."
            )(fn)

def python25(fn):
    return _chain_decorators_on(
        fn,
        skip_if(
            lambda: sys.version_info < (2, 5),
            "Python version 2.5 or greater is required"
        )
    )

def python2(fn):
    return _chain_decorators_on(
        fn,
        skip_if(
            lambda: sys.version_info >= (3,),
            "Python version 2.xx is required."
            )
    )

def skip_mysql_on_windows(fn):
    """Catchall for a large variety of MySQL on Windows failures"""

    return _chain_decorators_on(
        fn,
        skip_if(_has_mysql_on_windows,
            "Not supported on MySQL + Windows"
        )
    )

def ad_hoc_engines(fn):
    """Test environment must allow ad-hoc engine/connection creation.
    
    DBs that scale poorly for many connections, even when closed, i.e.
    Oracle, may use the "--low-connections" option which flags this requirement
    as not present.
    
    """
    return _chain_decorators_on(
        fn,
        skip_if(lambda: config.options.low_connections)
    )

def english_locale_on_postgresql(fn):
    return _chain_decorators_on(
        fn,
        skip_if(lambda: testing.against('postgresql') \
                and not testing.db.scalar('SHOW LC_COLLATE').startswith('en'))
    )

def sqlite(fn):
    return _chain_decorators_on(
        fn,
        skip_if(lambda: not _has_sqlite())
    )

def sane_multi_rowcount(fn):
    return _chain_decorators_on(
        fn,
        skip_if(lambda: not testing.db.dialect.supports_sane_multi_rowcount)
    )

def cextensions(fn):
    return _chain_decorators_on(
        fn,
        skip_if(lambda: not _has_cextensions(), "C extensions not installed")
    )