Hi Stuart, > To reset, you just iterate over sys.modules and reset everything that is a MagicMock (or anything with a reset_mock() method). There is no need to figure which to reset, since you want all of them reset every test to preserve test isolation. I haven't actually tried this bit yet.
Unfortunately, reset_mock doesn't reset as much as one would like it to. It resets the call attributes on the mock, but it won't reset side_effects and return_values. So if you rely on something like the options object in the base layer being replaced by a MagicMock in most of your tests, but you replace it with a fixture with some actual values in one of your tests, you run into trouble pretty quickly. :-( ~ PeteVG On Fri, Sep 9, 2016 at 8:53 PM Stuart Bishop <stuart.bis...@canonical.com> wrote: > On 9 September 2016 at 01:03, Pete Vander Giessen < > pete.vandergies...@canonical.com> wrote: > >> Hi All, >> >> > Stuart Bishop wrote: >> > The tearDown method could reset the mock easily enough. >> >> If only it were that simple :-) >> >> To patch imports, the harness was actually providing a context that you >> could use the wrap the imports at the top of your test module. That solved >> the immediate issue of executing imports without errors, but it created a >> very complex situation when you went to figure out which references to >> cleanup or update when you wanted to reset mocks. You also weren't able to >> clean them up in tearDown, or even tearDownClass, because you had to handle >> the situation where you had multiple test classes in a module. >> >> One workaround is to do your imports inside of the setUp for a test. That >> didn't feel like the correct way to do things in a library meant for >> general use, where I'd prefer to stick to things that don't make Guido sad. >> I wouldn't necessarily object to the technique if it came up in a code >> review for a specific charm, though :-) >> > > I'm thinking you insert a MagicMock into sys.modules instead of an import > statement (this is how we do it in the telegraf charm, and I'm sure helpers > could make this nicer): > > # Mock layer modules > import charms > promreg = MagicMock() > charms.promreg = promreg > sys.modules['charms.promreg'] = promreg > > To reset, you just iterate over sys.modules and reset everything that is a > MagicMock (or anything with a reset_mock() method). There is no need to > figure which to reset, since you want all of them reset every test to > preserve test isolation. I haven't actually tried this bit yet. > > If you are using the standard Python unittest feature set, I think you > would need a TestCase subclass to do the reset. If you are using py.test, I > think it has features that can do this magically. > > A moduleTearDown would be required if you want to remove the mocks from > sys.modules (or py.test magic). But I don't think we need to bother. > > > > -- > Stuart Bishop <stuart.bis...@canonical.com> >
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