New submission from Dima Tisnek:
Original use case:
I want to mock something that on invocation does 2 things:
* updates database
* returns custom, unrelated value
The problem:
side_effect is a catch-all setting that is used for:
* true side-effects
* return values
* exceptions
Moreover, side_effect takes precedence over return_value, unless the earlier
returns mock.DEFAULT. Very quirky.
Proposed change option 1:
Side-effect is not used as return value; explicit return value may be used for
that purpose.
(probably changes a lot of tests)
Proposed change option 2:
return_value, being more specific and explicit, takes precedence over
side_effect; that is side_effect is still executed but it's rv is lost if
overwritten by return_value is set.
(this is unlikely to change existing tests, as it is currently very odd to use
both side_effect and return_value at the same time.)
Current workaround 1:
mock.Mock(side_effect=lambda *args: [db.update(), mock.DEFAULT][-1],
return_value=42)
Current workaround 2:
mock.Mock(side_effect=lambda *args: [db.update(), 42][-1])
----------
components: Library (Lib)
messages: 228224
nosy: Dima.Tisnek
priority: normal
severity: normal
status: open
title: Support both side_effect and return_value in a more human way
type: enhancement
versions: Python 2.7, Python 3.1, Python 3.2, Python 3.3, Python 3.4, Python 3.5
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Python tracker <[email protected]>
<http://bugs.python.org/issue22541>
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