Generate admin password on db:seed

Test admin account creation in db:seed

test/system/tasks_test.rb

@@ -0,0 +1,24 @@
+require 'application_system_test_case'
+
+# NOTE: remove constant to avoid warnings due to double loading of
+# rails/tasks/statistics.rake. To be removed after upgrade to Rails 8.1.
+Object.send(:remove_const, :STATS_DIRECTORIES)
+
+Rails.application.load_tasks
+# NOTE: for some reason task for checking pending migrations messes up
+# transaction when run during test. It causes all DB changes made before its
+# execution to be rolled back.
+# Run it before tests, so any rake task dependent on it will see it as
+# #already_invoked and won't run it during test. It is redundant anyway, as
+# migrations are run before starting test suite.
+Rake::Task['db:abort_if_pending_migrations'].invoke
+
+class TasksTest < ApplicationSystemTestCase
+  test "db:seed creates admin account" do
+    User.admin.delete_all
+    assert_output /Creating admin account/ do
+      Rake::Task['db:seed'].execute
+    end
+    assert User.admin.exists?
+  end
+end