instead of deleting keys on every instantiation, create defaults we
actually use.  eventually we can pass an environment in to the request,
and create a new req / res object on each call.

merging cookies is responsibility of the test runner

For some reason, this special logic is only supposed to be executed on
the second request.  For now, we'll extend on recycle, but we should
figure out why this functionality can't be run on every request

Try to avoid making the controller mutate itself so that we can
eventually make the response async

To test uploading a file without using fixture_file_upload, a posted
ActionDispatch::Http::UploadedFile should not be paramified (just like
Rack::Test::UploadedFile).
(Rack::Test::UploadedFile and ActionDispatch::Http::UploadedFile don't
share the same API, tempfile is not accessible on
Rack::Test::UploadedFile as discussed in
https://github.com/brynary/rack-test/issues/30)

Fix incorrect assert_block -> assert conversion. Assumed too much from the MiniTest deprecation message.

This may break existing tests that are asserting the whole session contents
but should not break existing tests that are asserting individual keys - e.g:

class SomeControllerTest < ActionController::TestCase
  setup do
    session['user_id'] = 1
  end

  test "some test" do
    get :some_action, nil, { 'another_var' => 2 }

    # This assertion will now fail
    assert_equal({ 'another_var' => 2 }, session)

    # This assertion will still pass
    assert_equal 2, session['another_var]
  end
end

Fixes #1529.

fix the Flash middleware loading the session on every request (very dangerous especially with Rack::Cache), it should only be loaded when the flash method is called

We dont need to merge in the parameters as thats all being reset by the rack headers (and its causing problems for Strong Parameters attempt of wrapping request.parameters because it will change in testing)

This method has no effect since exception handling was
moved to middlewares and ActionController tests do not
use any middlewares.

This allows for more strict template assertions,
while maintaining backward compatibility.

For example, if you use assert_template("foo/bar")
and "foo/bar/baz" was rendered, the test passes.

But if you use assert_template(%r{\Afoo/bar\Z}),
you will catch that a different template was
rendered.

Also, if you passed an unsupported argument to
assert_template() in the past, it would silently
succeed. Now it raises an ArgumentError.

PATCH is the correct HTML verb to map to the #update action. The
semantics for PATCH allows for partial updates, whereas PUT requires a
complete replacement.

Changes:
* adds config.default_method_for_update you can set to :patch
* optionally use PATCH instead of PUT in resource routes and forms
* adds the #patch verb to routes to detect PATCH requests
* adds #patch? to Request
* changes documentation and comments to indicate support for PATCH

This change maintains complete backwards compatibility by keeping :put
as the default for config.default_method_for_update.

- instance_variables return symbols in 1.9
- there is instance_variable_defined? method

This reverts commit f53c247d.