How to patch and verify if a Class was instantiated with a specific parameter? [duplicate]

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• Python: Mock Patch Errors with Flask 1 answer

In a nutshell this is the class I would like to test. To see if Tokenizer('english') was created with 'english'.

def summarize(news):
        language = 'english'
        parser = PlaintextParser.from_string(news.body, Tokenizer(language))

This is the test

    @mock.patch.object(PlaintextParser, 'from_string')
    @mock.patch('sumy.nlp.tokenizers.Tokenizer')
    def test_summarize_tokenizer_is_called_with_english(self, token_mock, parser_mock):
        news_mock = mock.MagicMock()
        body = u"xx"
        type(news_mock).body = mock.PropertyMock(return_value=body)
        Summarizer.summarize(news_mock)
        token_mock.assert_called_with('english')

I keep getting:

AssertionError: Expected call: Tokenizer('english')
Not called

But this should pass. What am I missing please?