While we are unable to support OAUTH2 with pop3 (due to upstream dependency ruby/net-pop#16), we are adding the support for mail pollers plugin. Doing so, it would be possible to write a plugin which then uses other ways (microsoft graph sdk for example) to poll emails from a mailbox.
The idea is that a plugin would define a class which inherits from Email::Poller and defines a poll_mailbox static method which returns an array of strings. Then the plugin could call register_mail_poller(<class_name>) to have it registered. All the configuration (oauth2 tokens, email, etc) could be managed by sitesettings defined in the plugin.
Introduces a new API for plugin data modification without class-based extension overhead.
This commit introduces a new API that allows plugins to modify data in cases where they return different data rather than additional data, as is common with filtered_registers in DiscoursePluginRegistry. This API removes the need for defining class-based extension points.
When a plugin registers a modifier, it will automatically be called if the plugin is enabled. The core will then modify the parameter sent to it using the block registered by the plugin:
```ruby
DiscoursePluginRegistry.register_modifier(plugin_instance, :magic_sum_modifier) { |a, b| a + b }
sum = DiscoursePluginRegistry.apply_modifier(:magic_sum_filter, 1, 2)
expect(sum).to eq(3)
```
Key features of these modifiers:
- Operate in a stack (first registered, first called)
- Automatically disabled when the plugin is disabled
- Pass the cumulative result of all block invocations to the caller
It's very easy to forget to add `require 'rails_helper'` at the top of every core/plugin spec file, and omissions can cause some very confusing/sporadic errors.
By setting this flag in `.rspec`, we can remove the need for `require 'rails_helper'` entirely.
