modularised cpdAssign

[j-emberton]

No description provided.

[j-emberton]

@dorchard @isaacaka would appreciate it if you think there's any more sensible moves to modularise this function further. Its a bit of a mess of repeated mutation and early exit.

[dorchard]

Delayed waiting on the more unified cross-language testing approach.

[dorchard]

Note the tests use jsondecode which we may want to avoid going through into the Python.
Therefore in conftest.py we need to drop that keyword in the test engine, e.g.,

                if 'jsondecode' in kwargs:
                    kwargs.pop('jsondecode')

in the newfunc function.