After 9d378747 `ActionDispatch::IntegrationTest`
class is loaded and defined in all Rails environments, not only test but also
production. This is not-intended loading of a class which is only used in
test environment.
To prevent not-intended loading, add `ActiveSupport.run_load_hooks` to
`ActionDispatch::IntegrationTest` with `action_dispatch_integration_test` name
and use it in `ActionMailer`.

It's probably obvious to most, but clarify that `:helper_method` will make both
of these methods available to the view.

Forgot to update the documentation on the line just above the one
I was changing in 49331322. Well done, Kasper 👍

`ActionDispatch::SSL` redirects all HTTP requests to HTTPS, not just some.
The `constrain_to` option inverts this, so it sounds like the middleware
only handles a few requests, rather than the majority with a few routes to
opt out of the redirect.

Renaming to `exclude` matches this intent more closely.

Follow-up to #23980.

- Fix grammar: "be remove" -> "be removed".

- Wrap lines at 80 chars.

Lurvely ;-)

This reverts changes made to integration tests in PR #23807.
The issue happens when using capybara with a driver that needs to start a
server in a separate thread like (poltergeist, selenium, etc).
Both threads the capybara server one and the test thread end running
syncronize over the interlock.

When trying to make a request and the request doesn't have a suitable template, the new error messages are really helpful but there's a small (and I mean, VERY small) typo that has been bugging me for the last few days. This adds the space and restores order to the universe. ❤

These should allow external code to run blocks of user code to do
"work", at a similar unit size to a web request, without needing to get
intimate with ActionDipatch.

Allowing :controller and :action values to be specified via the path
in config/routes.rb has been an underlying cause of a number of issues
in Rails that have resulted in security releases. In light of this it's
better that controllers and actions are explicitly whitelisted rather
than trying to blacklist or sanitize 'bad' values.

We only reference the Action Controller error classes by name in
ActionDispatch::ExceptionWrapper, so there is no need to explicitly
require them.

It drops a tiny coupling between Action Dispatch and Action Controller,
so it makes me feel warm inside. We still have a lot of others AC
requires in the AD code base, but here, we can save it.

[ci skip]

This reverts commit 22db455d, reversing
changes made to 40be61df.

This finishes off what I meant to do in 6216a092.

This reverts commit 45a75a3f.

HWIAs are better than silently deeply-stringified hashes... but that's a
reaction to a shortcoming of one particular session store: we should not
break the basic behaviour of other, more featureful, session stores in
the process.

Fixes #23884

* Fixes typos in error message and release notes.
* Removes unused template test file.

1. Conceptually revert #20276

   The feature was implemented for the `responders` gem. In the end,
   they did not need that feature, and have found a better fix (see
   plataformatec/responders#131).

   `ImplicitRender` is the place where Rails specifies our default
   policies for the case where the user did not explicitly tell us
   what to render, essentially describing a set of heuristics. If
   the gem (or the user) knows exactly what they want, they could
   just perform the correct `render` to avoid falling through to
   here, as `responders` did (the user called `respond_with`).

   Reverting the patch allows us to avoid exploding the complexity
   and defining “the fallback for a fallback” policies.

2. `respond_to` and templates are considered exhaustive enumerations

   If the user specified a list of formats/variants in a `respond_to`
   block, anything that is not explicitly included should result
   in an `UnknownFormat` error (which is then caught upstream to
   mean “406 Not Acceptable” by default). This is already how it
   works before this commit.

   Same goes for templates – if the user defined a set of templates
   (usually in the file system), that set is now considered exhaustive,
   which means that “missing” templates are considered `UnknownFormat`
   errors (406).

3. To keep API endpoints simple, the implicit render behavior for
   actions with no templates defined at all (regardless of formats,
   locales, variants, etc) are defaulted to “204 No Content”. This
   is a strictly narrower version of the feature landed in #19036 and
   #19377.

4. To avoid confusion when interacting in the browser, these actions
   will raise an `UnknownFormat` error for “interactive” requests
   instead. (The precise definition of “interactive” requests might
   change – the spirit here is to give helpful messages and avoid
   confusions.)

Closes #20666, #23062, #23077, #23564

[Godfrey Chan, Jon Moss, Kasper Timm Hansen, Mike Clark, Matthew Draper]

- For old apps which are not setting any value for hsts[:subdomains],
  a deprecation warning will be shown saying that hsts[:subdomains] will
  be turned on by default in Rails 5.1. Currently it will be set to
  false for backward compatibility.
- Adjusted tests to reflect this change.

1) Because if you forget to add Secure; to the session cookie, it will leak to http:// subdomain in some cases
2) Because http:// subdomain can Cookie Bomb/cookie force main domain or be used for phishing.

That's why *by default* it must include subdomains as it's much more common scenario. Very few websites *intend* to leave their blog.app.com working over http:// while having everything else encrypted. 

Yes, many developers forget to add subdomains=true by default, believe me :)

- Fixes #23822.

Abstract Controller is the common component between Action Mailer and
Action Controller so if we need to share the caching component it need
to be there.

Remove useless helper in ActionDispatch::Caching and fix indentation

Move most caching methods to ActionDispatch::Caching, and let ActionMailer and ActionController to include it

This bug affects `wss://` requests when running Action Cable in-app.
Fixes #23620.

This is meant to provide a way for Action Cable, Sprockets, and possibly
other Rack applications to mark themselves as internal, and to exclude
themselves from the routing inspector, and thus `rails routes` / `rake
routes`.

I think this is the only way to have mounted Rack apps be marked as
internal, within AD/Journey. Another option would be to create an array
of regexes for internal apps, and then to iterate over that everytime a
request comes through. Also, I only had the first `add_route` method set
`internal`'s default to false, to avoid littering it all over the
codebase.

This will keep our current API working without having the users to
change their codebases.

After registering new `:json` mime type `parsers.fetch` can't find the mime type because new mime type is not equal to old one. Using symbol of the mime type as key on parsers hash solves the problem.

Closes #23766

Creating a protected getter method for `@parameters`.