assertRaises WTF?

test_build.py

#Unit test that is failing.
class Test_BuildApp(unittest.TestCase):
    def test_isNotApp(self):
        build_fail = build.BuildApp(self.test_app_fail_path)
        self.assertRaises(build.BuildAppException, build_fail.isApp())

# Code it is testing (in build.py)
class BuildApp:
    def isApp(self):
        if "/" in self.path:
            self.app_dir = self.path.split("/").pop()
        else:
            self.app_dir = self.path
        for root, dirs, files in os.walk(self.path):
            if "descriptor.xml" in files:
                return True
        raise BuildAppException("Could not find descriptor.xml in path: %s" % (self.path), "BuildError")

# Exception it is raising (in build.py)
class BuildAppException(Exception):
    def __init__(self, message, e):
        Exception.__init__(self, message)
        self.log = logging.getLogger("Exception")
        self.log.addHandler(log_handler)
        self.logError(message, e)
    
    def logError(self, e, message):
        return self.log.critical("%s! %s" % (str(e), message)) 

Problem child is line 5 - build_fail isApp() should be "build_fail.isApp". assertRaises takes a callable, not a method.