Adds a DOCKER env variable, to disable sandbox mode for system tests

Fixes rubocop offense - || instead of or

Comments out the DOCKER variable

Corrects the syntax for Markdown inline code

.env.test

@@ -35,3 +35,6 @@ OPENID_REFRESH_TOKEN="dummy-refresh-token"
 ACTIVE_RECORD_ENCRYPTION_PRIMARY_KEY="test_primary_key"
 ACTIVE_RECORD_ENCRYPTION_DETERMINISTIC_KEY="test_deterministic_key"
 ACTIVE_RECORD_ENCRYPTION_KEY_DERIVATION_SALT="test_derivation_salt"
+
+# Let the tests know if they are run within a Docker container:
+# DOCKER="true"

docker/README.md

@@ -5,6 +5,8 @@ Docker is intended to provide a common virtual environment available to all deve
 ## Limitations
 1. The docker environment can't directly control your host system browser, which means that browser specs (under `/spec/system/`) and email previews will not work. You may be able to find a solution with [this article](https://evilmartians.com/chronicles/system-of-a-test-setting-up-end-to-end-rails-testing). If so, please contribute!
 
+2. You can try circumventing this by setting the option `DOCKER=true` on the `.env.test file`, which will disable the `sandbox` mode for Chrome, used for system tests.
+
 ## Installing Docker
 ### Requirements
 * You should have at least 2 GB free on your local machine to download Docker images and create Docker containers for this app.

spec/system/support/cuprite_setup.rb

@@ -5,7 +5,7 @@ require "capybara/cuprite"
 headless = ActiveModel::Type::Boolean.new.cast(ENV.fetch("HEADLESS", true))
 
 browser_options = {}
-browser_options["no-sandbox"] = nil if ENV['CI']
+browser_options["no-sandbox"] = nil if ENV['CI'] || ENV['DOCKER']
 
 Capybara.register_driver(:cuprite_ofn) do |app|
   Capybara::Cuprite::Driver.new(