Set Rails environment to test before invoking extension:test_app task

[gsmendoza]

This fixes the following error when running bundle exec rake in
SolidusPaypalCommercePlatform:

An error occurred in a `before(:suite)` hook.
Failure/Error: //= link spree/backend/all.js

Sprockets::FileNotFound:
  couldn't find file 'spree/backend/all.js'
  Checked in these paths:
    /home/gsmendoza/repos/solidusio-contrib/solidus_paypal_commerce_platform/spec/dummy/app/assets/config
    /home/gsmendoza/repos/solidusio-contrib/solidus_paypal_commerce_platform/spec/dummy/app/assets/images
    /home/gsmendoza/repos/solidusio-contrib/solidus_paypal_commerce_platform/spec/dummy/app/assets/stylesheets
    /home/gsmendoza/repos/solidusio-contrib/solidus_paypal_commerce_platform/app/assets/javascripts
    /home/gsmendoza/repos/solidusio-contrib/solidus_paypal_commerce_platform/app/assets/stylesheets

Cause

extension:specs, the default rake task of SolidusPaypalCommercePlatform,
executes the rake tasks and Ruby methods below in the given order:

• The extension namespace defined in
  SolidusDevSupport::RakeTasks#install_test_app_task. This namespace invokes
  the extension:test_app task
  (

  solidus_dev_support/lib/solidus_dev_support/rake_tasks.rb

  Line 47 in e5fec9c

  Rake::Task['extension:test_app'].invoke

  ).

• The Solidus extension:test_app task
  (https://github.com/solidusio/solidus/blob/07c88ddd1603699939ac0343965fa88dc2e1851a/core/lib/spree/testing_support/extension_rake.rb#L7)

• The common:test_app rake task in CommonRakeTasks#initialize
  (https://github.com/solidusio/solidus/blob/07c88ddd1603699939ac0343965fa88dc2e1851a/core/lib/spree/testing_support/common_rake.rb#L14)

• Solidus::InstallGenerator#setup_assets
  (https://github.com/solidusio/solidus/blob/07c88ddd1603699939ac0343965fa88dc2e1851a/core/lib/generators/solidus/install/install_generator.rb#L81)

The setup_assets method would only install the all.* frontend and backend
assets if either

• Spree::Frontend and Spree::Backend are loaded, or
• The Rails environment is test.

Currently, when we run bundle exec rake in SolidusPaypalCommercePlatform,
neither condition is met:

• Spree::Frontend and Spree::Backend are NOT loaded.
• The Rails environment is development.

Trigger

This bug surfaced after we applied solidusio/solidus#4251 (Fix: solidus:install adds the frontend
assets even if the repo does not have solidus_frontend).

Solution

Considering that the extension:test_app rake task generates the
spec/dummy directory, we can assume that it is expected to run under
test environment.

Testing

• gsmendoza/eng-340-fix-soliduspaypalcommerceplatform-bundle--debug tests the fix against SolidusPaypalCommercePlatform. Here's the output of its bundle exec rake stripped off deprecation warnings and other noise: 2022-06-08-solidus-paypal-commerce-platform-output.txt.

Checklist

• I have structured the commits for clarity and conciseness.
• I have added relevant automated tests for this change.

[mergify]

It looks like this PR is missing a label to determine the type of change it introduces. The maintainer should add one of the following labels:

• bug for bugfixes.
• enhancement for new features and improvements.
• documentation for documentation changes.
• security for security patches.
• removed for feature removals.
• infrastructure for internal changes that should not go in the changelog.

Additionally, the maintainer may also want to add one of the following:

• breaking for breaking changes.
• deprecated for feature deprecations.

Once the correct labels have been set, simply remove the needs changelog label label from this PR so I can merge it.

[gsmendoza]

@waiting-for-dev In SolidusPaypalCommercePlatform's case, the extension:test_app wrapper task defined in lib/solidus_dev_support/rake_tasks.rb is invoked after Solidus::InstallGenerator runs. To recap, here are all the tasks and Ruby methods executed by bundle exec rake in SolidusPaypalCommercePlatform, including the extension:test_app wrapper task.

1. The extension namespace defined in SolidusDevSupport::RakeTasks#install_test_app_task, which invokes
   the extension:test_app task.
2. The Solidus extension:test_app task
3. The common:test_app rake task in CommonRakeTasks#initialize
4. Solidus::InstallGenerator
5. The extension:test_app wrapper task in SolidusDevSupport (the test_app task above)
6. The Solidus extension:test_app task again
7. extension:specs, which is the default task of SolidusPaypalCommercePlatform

I'm guessing that the extension:test_app wrapper task (Step 5 above) is called as part of the whole invocation of the extension:test_app task. That invocation calls the "original" Solidus extension:test_app task first, before calling the overriding extension:test_app task from SolidusDevSupport.

Considering that Step 1 has already set up ENV['RAILS_ENV'] = 'test', there is no need to do the same for the extension:test_app wrapper task (Step 5 above), except to make it consistent with the change I made to Rake::Task['extension:test_app'].invoke below. Let me know if you prefer to err on the side of consistency.

Finaly, note that when the Solidus extension:test_app task is invoked a second time (in Step 6), it doesn't do anything. I still have to check but I'm guessing this is a normal behavior for Rake: it runs a task only once.

I'm making several guesses here concerning Rake, so I'll need to review Rake's documentation, especially with regard to how it handles overridden rake tasks.

[gsmendoza]

Closing this for now. I have just noticed that common:test_app already sets up RAILS_ENV to test, but it's not being picked up by Solidus::InstallGenerator. Will investigate.