Json dumps while reading file as mock

I want to make a simple imitation of reading the file using mock_open and then to make a simple test that would show me, the mock_open didn't break anything. The problem is that the mock_file is like this:

<MagicMock name='open' spec='builtin_function_or_method' id='140399632712176'>

and as a result I am not able to json.dumps it, so it would return to the JSON format. The error I get is:

TypeError: the JSON object must be str, bytes or bytearray, not builtin_function_or_method

Is there any way to "unmock" the mocked file?

My test code:

    def test_get_all_students_true_148(self):
        stub_storage = self.storage
        stub_register = self.register
        data = mock_open(read_data=json.dumps([
            {'id': 1, 'firstName': "User", 'lastName': "Random"},
            {'id': 2, 'firstName': "User 2", 'lastName': "Random 2"},
            {'id': 3, 'firstName': "User 3 ", 'lastName': "Random 3"}
        ]))
        with patch('builtins.open', data) as mock_file:
            data_to_return = json.loads(mock_file)
            stub_storage.get_students = MagicMock(return_value=data_to_return)
            assert_that(stub_register.get_students(), [
                {'id': 1, 'firstName': "User", 'lastName': "Random"},
                {'id': 2, 'firstName': "User 2", 'lastName': "Random 2"},
                {'id': 3, 'firstName': "User 3 ", 'lastName': "Random 3"}
            ])

CodePudding user response：

mock_open() mocks the open() builtin function.

Just as you wouldn't do json.loads(open), you can't do json.loads(mock_open()).

On top of that, json.loads() receives a string and not a file. For that use json.load().

Fixed code:

from unittest.mock import *
import json

data = mock_open(read_data=json.dumps([
            {'id': 1, 'firstName': "User", 'lastName': "Random"},
            {'id': 2, 'firstName': "User 2", 'lastName': "Random 2"},
            {'id': 3, 'firstName': "User 3 ", 'lastName': "Random 3"}
        ]))

with patch('builtins.open', data) as new_open:
    data_to_return = json.load(new_open())