Improve upon test suite flakiness

[seanpdoyle]

Make turbo_test.rb with Rails' generated test_helper.rb

Something in the test suite configuration is preventing the database
from being wiped between test runs. This results in state leaking
between tests. As a result, our Continuous Integration tests are flaky.

• hotwired/turbo-rails#248

As a follow-up to the short-term solution shipped in
hotwired/turbo-rails#248, this commit attempts to make the
test/turbo_test.rb file's setup consistent with the test harness setup
generated by Rails' engine generator code.

To that end, this commit:

• renames the test/turbo_test.rb file to test/test_helper.rb
• omits one-off require calls for particular dependencies
• re-orders the require calls so that the
  ../test/dummy/config/environment file is required ahead of the
  rails/test_help file

Use Ruby 2.7 argument forwarding

Switching to argument forwarding addresses deprecation warnings like:

hotwired/turbo-rails/test/streams/streams_channel_test.rb:140: warning: Using the last argument as keyword parameters is deprecated; maybe ** should be added to the call
hotwired/turbo-rails/test/turbo_test.rb:14: warning: The called method `render' is defined here

Tests: Load 6.1 defaults in Dummy Application

Resolve deprecation warnings like:

Preparing test database
DEPRECATION WARNING: Non-URL-safe CSRF tokens are deprecated. Use 6.1 defaults or above. (called from <top (required)> at /home/runner/work/turbo-rails/turbo-rails/test/dummy/config/initializers/inspect_helpers.rb:1)
DEPRECATION WARNING: Using legacy connection handling is deprecated. Please set
`legacy_connection_handling` to `false` in your application.

The new connection handling does not support `connection_handlers`
getter and setter.

Read more about how to migrate at: https://guides.rubyonrails.org/active_record_multiple_databases.html#migrate-to-the-new-connection-handling
 (called from <top (required)> at /home/runner/work/turbo-rails/turbo-rails/test/test_helper.rb:6)

Since our GitHub CI matrix includes 6.1, 7.0, and main, CI's tests
should run with at least the 6.1 defaults.

CI: Continue other executions on error

Remove the continue-on-error configuration and instead allow other
jobs complete in spite of failures.

Improve flaky Broadcast tests

First, don't render HTML with the <turbo-cable-stream-source> element.
Instead, append the element when clicking a <button>.

Next, remove all waiting from Capybara tests, and rely on default
values.

[dhh]

Dig that. Seems like we have some test errors, but maybe that's related to this other PR I just merged. Looks like those tests might be flaky?

[seanpdoyle]

The current batch of CI failures here (and in #328) seem related to test/system/broadcasts_test.rb, which was recently introduced in #308.

[dhh]

Cc @yrashk

[dhh]

Seems like we still have some Rails 6.1 failures?

[seanpdoyle]

This is passing, finally.