Integration tests that check the output of time_ago_in_words are unable to access translations

[hannako]

Service manual frontend is soon to be retired, and the first step in that process was importing the templates, helpers and specs from the existing repo into this application. See #2583

Imported integration tests that check for the output of a rails helper are failing and have been skipped.

Original test in service manual frontend

test "shows the time it was saved if it hasn't been published yet" do
    now = "2015-10-10T09:00:00+00:00"
    last_saved_at = "2015-10-10T08:55:00+00:00"

    travel_to(now) do
      example = simulate_example_as_first_edition_on_draft_stack(
        govuk_content_schema_example(
          "service_manual_guide",
          "service_manual_guide",
          updated_at: last_saved_at,
        ),
      )
      base_path = example.fetch("base_path")
      stub_content_store_has_item(base_path, example)
      visit base_path

      within(".app-change-history") do
        assert page.has_content?("5 minutes ago")
      end
    end
  end

Running that test in service manual frontend passes. But running that test once imported to this application results in translation missing: en.datetime.distance_in_words.x_days:

test_shows_the_time_it_was_saved_if_it_hasn't_been_published_yetERROR (2.10s)
Minitest::UnexpectedError:         
Capybara::ExpectationNotMet: expected to find text "5 minutes ago" in 
"From:\nAgile delivery community\nLast updated\ntranslation missing: en.datetime.distance_in_words.x_days ago\nLast update:\n9 October 2015\nThis is our latest change\n+ Show all page updates (2)\n9 September 2015\nThis is another change\n1 September 2015\nGuidance first published"

Details

• time_ago_in_words is method defined in ActionView::DateHelper
• as per the Rails docs, that helper has built in I18n support, accessing translations from this locale file.
• Adding a debugger to the test, and inspecting I18n.backed.translations[:en][:datetime] confirms that those keys are available to the helper, but something in the configuration of the test suite is preventing the helper using them.

NOTE: Once the migration PR is merged, links to the test and the files calling the helper will be added to this issue