Add some validation logic to TrianglePandas.rename

[genedan]

Are you on the latest chainladder version?

• Yes, this bug occurs on the latest version.

Describe the bug in words

Some nonsense values can be passed to TrianglePandas.rename without triggering an exception. Instead, the method simply returns self if none of the conditional branches are triggered:

value = [value] if type(value) is str else value
        if axis == "index" or axis == 0:
            self.index = value
        if axis == "columns" or axis == 1:
            self.columns = value
        if axis == "origin" or axis == 2:
            self.origin = value
        if axis == "development" or axis == 3:
            self.development = value
        return self

Users may end up believing that something was renamed, when instead nothing actually happened.

How can the bug be reproduced?

The following is an example where the user mistypes "columns" as "colunms".

genins = cl.load_sample('genins')
genins.rename('colunms', 'bar')

What is the expected behavior?

A ValueError should be triggered, notifying the user that an invalid value was passed to the axis argument.