Adds the magic `frozen_string_literal: true` comment to every file and
enables a Rubocop rule to make sure that it's always going to be there
going forward as well.
See here for more background [1], but the basic idea is that unlike many
other languages, static strings in code are mutable by default. This has
since been acknowledged as not a particularly good idea, and the
intention is to rectify the mistake when Ruby 3 comes out, where all
string literals will be frozen. The `frozen_string_literal` magic
comment was introduced in Ruby 2.3 as a way of easing the transition,
and allows libraries and projects to freeze their literals in advance.
I don't think this is breaking in any way: it's possible that users
might've been pulling out one of are literals somehow and mutating it,
but that would probably not have been useful for anything and would
certainly not be recommended, so I'm quite comfortable pushing this
change through as a minor version.
As discussed in #641.
[1] https://stackoverflow.com/a/37799399
Makes the `operations` argument to `nested_resource_class_methods`
required and adds explicit lists to any invocations that were missing
one.
The impetus here is that I think it's more easily digestible if each
call site is explicit about what operations it supports and therefore
which methods it's about to create on the class.
As described in #481, adding a protected field like `legal_entity` as
part of an update API operation can cause some issues like a custom
encoding scheme not being considered and special handling around empty
values being ignored.
As a an easy fix for this, let's disallow access to protected fields in
the same way that we disallow them from being set directly on an
instance of a given model.
Helps address (but is not a complete fix for) #481.
* Rename the `Update` operation to `Save`
* Add the `update` class method to all saveable resources
* Add tests for update method
* Add tests for plans, invoice items, and application fees
