def test_autocreate(self):
        self.env.auto_build = True
        self.mkbundle('in1', output='out').urls()
        assert self.get('out') == 'A'
If an output file doesn't yet exist, it'll be created.
dataset/ETHPy150Open miracle2k/webassets/tests/test_bundle_build.py/TestAutoBuild.test_autocreate