def METHOD_NAME(self):
    """
    Test altering columns.
    """
    manager_1 = MigrationManager()
    manager_1.add_table(class_name="Manager", tablename="manager")
    manager_1.add_column(
        table_class_name="Manager",
        tablename="manager",
        column_name="name",
        column_class_name="Varchar",
        params={"length": 100},
    )
    manager_2 = MigrationManager()
    manager_2.alter_column(
        table_class_name="Manager",
        tablename="manager",
        column_name="name",
        params={"unique": True},
        old_params={"unique": False},
    )
    schema_snapshot = SchemaSnapshot(managers=[manager_1, manager_2])
    snapshot = schema_snapshot.get_snapshot()
    self.assertTrue(snapshot[0].columns[0]._meta.unique)