def METHOD_NAME(self):
    class Test(Struct):
        field1 = Field(str, default='42')
        field2 = Field(bool)
    with self.assertRaisesRegex(TypeError, 'field2 is required'):
        Test()
    t = Test(field2=False)
    assert t.field1 == '42'
    assert t.field2 is False
    assert set(t) == {'field1', 'field2'}