pytest mock method result

Question

I have this class method

def _copy_blob(self, source_blob: str, target_file_path: str) -> None:
    """
    Copy blob to a new location
    :param source_blob:
    :param target_file_path:
    """
    copied_blob = self.blob_service_client.get_blob_client(self.container, target_file_path)
    copied_blob.start_copy_from_url(source_blob)

I wrote unit test for the first line:

def test_copy_blob(mocker, file, source_blob, target_file_path):
    blob_service_client_mock = mocker.MagicMock()
    blob_service_client_mock.account_name = 'test_account'
    file = TestClass(file, blob_service_client_mock, container='test')
    file._copy_blob(source_blob, target_file_path)
    blob_service_client_mock.get_blob_client.assert_any_call('test', target_file_path)

How can I test copied_blob.start_copy_from_url(source_blob) has been called?

score 1 · Answer 1 · edited Apr 06 '22 at 08:20

You will do it by patching the get_blob_client method.

Here we miss a little context, but let's imagine the following augmentation of your code:

from blob_service_client import BlobServiceClient
class BlobBlop:
    def __init__():
        self.blob_service_client = BlobServiceClient()

    def _copy_blob(self, source_blob: str, target_file_path: str) -> None:
        """
        Copy blob to a new location
        :param source_blob:
        :param target_file_path:
        """
        copied_blob = self.blob_service_client.get_blob_client(self.container, target_file_path)
        copied_blob.start_copy_from_url(source_blob)

The test would be:

import ...

@patch("yourpath.yourmodule.BlobServiceClient")
def test__copy_blob(patched_blob_service_client):
    mocked_blob_service_client = Mock()


    patched_blob_service_client.return_value = mocked_blob_service_client 

    mocked_blob_client = Mock()
    mocked_blob_service_client.get_blob_client.return_value = mocked_blob_client

    test_object = BlobBlop()

    test_object._copy_blob("the_source_blob", "the_target_path")

    mocked_blob_client.start_copy_from_url.assert_called_with("the_source_blob")

score 0 · Answer 2 · answered Apr 03 '22 at 09:28

blob_service_client_mock.get_blob_client.return_value.start_copy_from_url.assert_called()

blob_service_client_mock.get_blob_client.return_value is what will be returned by blob_service_client_mock.get_blob_client(), so copied_blob in your case (docs: return_value). The rest is just the assertion.

pytest mock method result

2 Answers2