Add tests for date formats initializer

spec/config/initializers/date_formats_spec.rb

@@ -0,0 +1,35 @@
+require "rails_helper"
+
+RSpec.describe "Time::DATE_FORMATS" do
+  describe ":govuk_date_and_time, :govuk_time formats" do
+    it "formats time to indicate midday" do
+      date_and_time = Time.zone.local(2020, 12, 25, 12, 0, 59)
+      expect(date_and_time.to_formatted_s(:govuk_date_and_time)).to eq("25 December 2020 at 12pm (midday)")
+      expect(date_and_time.to_formatted_s(:govuk_time)).to eq("12pm (midday)")
+    end
+
+    it "formats time to indicate midnight" do
+      date_and_time = Time.zone.local(2020, 12, 25, 0, 0, 59)
+      expect(date_and_time.to_formatted_s(:govuk_date_and_time)).to eq("25 December 2020 at 12am (midnight)")
+      expect(date_and_time.to_formatted_s(:govuk_time)).to eq("12am (midnight)")
+    end
+
+    it "formats time with minutes if the time is not on the hour" do
+      date_and_time = Time.zone.local(2020, 12, 25, 12, 1, 0)
+      expect(date_and_time.to_formatted_s(:govuk_date_and_time)).to eq("25 December 2020 at 12:01pm")
+      expect(date_and_time.to_formatted_s(:govuk_time)).to eq("12:01pm")
+    end
+
+    it "formats time without minutes if the time is on the hour" do
+      date_and_time = Time.zone.local(2020, 12, 25, 15)
+      expect(date_and_time.to_formatted_s(:govuk_date_and_time)).to eq("25 December 2020 at 3pm")
+      expect(date_and_time.to_formatted_s(:govuk_time)).to eq("3pm")
+    end
+
+    it "does not pad single-digit day and hour with whitespace" do
+      date_and_time = Time.zone.local(2020, 12, 5, 6, 10, 0)
+      expect(date_and_time.to_formatted_s(:govuk_date_and_time)).to eq("5 December 2020 at 6:10am")
+      expect(date_and_time.to_formatted_s(:govuk_time)).to eq("6:10am")
+    end
+  end
+end