Non-immutable content of input_groups for WorkChains

[giovannipizzi]

If I do the following test, it fails as the content of the input group is not immutable and the next step will still see the changes.

This instead does not work with self.inputs as this is a FrozenDict. If this is the expected behaviour, this should be extended to groups.

As a side note, I think groups were implemented to solve the problem of use_ methods with an additional flag to be passed (e.g.: pseudos) and are now being (mis)used by many users just for organisational purposes, to group together inputs. Is this ok? (This also doesn't perform checks/validations, but I got from @sphuber that maybe in the next version this behaviour changed?)

    def test_immutable_input_groups(self):
        """
        Check that self.inputs.xxx are not modifiable where xxx is an input_group
        """
        test_class = self

        class Wf(WorkChain):
            @classmethod
            def define(cls, spec):
                super(Wf, cls).define(spec)
                spec.input_group('grp')
                # Try defining an invalid outline
                spec.outline(
                    cls.s1,
                    cls.s2,
                )

            def s1(self):
                grp = self.inputs.grp
                # I manipulate this 'inputs' dict - I expect that in the next step
                # self.inputs is not changed

                ## If we want the same behavior for group as for inputs, we want these exceptions to be raised
                ## Otherwise, if the dictionary can be changed, still we want the next test (in step s2) to work.
                with test_class.assertRaises(TypeError): # 'AttributesFrozendict' object does not support item assignment
                    grp['one'] = Int(3)
                with test_class.assertRaises(AttributeError): # AttributeError: 'AttributesFrozendict' object has no attribute 'pop'
                    grp.pop('two')
                with test_class.assertRaises(TypeError): # 'AttributesFrozendict' object does not support item assignment
                    grp['four'] = Int(4)

            def s2(self):
                grp = self.inputs.grp
                # a and b should be still there
                test_class.assertIn('one', grp)
                test_class.assertIn('two', grp)
                test_class.assertNotIn('four', grp)
                # The value should still be the original one, unmodified
                test_class.assertEquals(grp['one'].value, 1)

        x = Int(1)
        y = Int(2)
        run(Wf, grp={'one': x, 'two': y})

[giovannipizzi]

I added a new branch (see referenced commit here above) with two new tests (one passing for self.inputs, one failing for input_groups

[sphuber]

This was addressed in issue #196 which was fixed in PR #1099