How to mock multiple return values in Easymock

Question

I am a python newbie and am trying to mock process.communicate method, but i do not know how to return multiple values from mock. The way i am approaching it is

with patch.object(subprocess, 'Popen', new_callable=MagicMock) as process:
  process.communicate.return_value = [b'', b'']
  output, error = process.communicate()

The error message i am getting is :

>       output, error = process.communicate()
E       ValueError: not enough values to unpack (expected 2, got 0)

Can someone please point out what wrong am i doing, i have tried returning with and without square and curly braces.

score 0 · Answer 1 · answered Dec 22 '16 at 06:19

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process.communicate returns a tuple and not a list so all you need to change is to:

with patch.object(subprocess, 'Popen', new_callable=MagicMock) as process:
  process.communicate.return_value = (b'', b'')
  output, error = process.communicate()

In general in Python when you return a tuple it can be returned into a tuple pointer or unpacked to multiple values. For more info you can go here (First on Google)

answered Dec 22 '16 at 06:19

Uri Shalit

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Thanks for the response, able to fix this issue. The bug was at someplace else and after fixing that returning values with braces worked fine. – Ankit Dixit Dec 22 '16 at 06:36

score 0 · Answer 2 · answered Dec 22 '16 at 06:38

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Sorry for the mis-information, but i have found out that the error was in some different part of the code and the above mentioned syntax works fine with our without any kind of braces.

answered Dec 22 '16 at 06:38

Ankit Dixit

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How to mock multiple return values in Easymock

2 Answers2