Fix DirectMessage.today on different time zones

The dates are saved on UTC times on the database. So, for example,
if living in West Australia, `Date.current.beginning_of_day` will be
stored as UTC's yesterday at 15:15:00, while `Date.current.end_of_day`
will be stored as UTC's today at 15:14:59.

When we use the `DATE` database function, PostgreSQL will select the
records with the same UTC date as the current UTC date. However, we need
the records with the same application date (as defined in
`config.time_zone`) as the current application date. The test passed
(for us) because we were using `beginning_of_day + 3.hours` to make sure
we were creating records when the date in Madrid was the same as the UTC
date.

Using a ruby interval for the time condition solves the problem.

app/models/direct_message.rb

@@ -8,7 +8,7 @@ class DirectMessage < ApplicationRecord
   validates :receiver, presence: true
   validate  :max_per_day
 
-  scope :today, lambda { where("DATE(created_at) = DATE(?)", Time.current) }
+  scope :today, lambda { where(created_at: Date.current.beginning_of_day..Date.current.end_of_day) }
 
   def max_per_day
     return if errors.any?

spec/models/direct_message_spec.rb

@@ -75,11 +75,11 @@ describe DirectMessage do
 
   describe "scopes" do
 
-    describe "today" do
+    describe "today", :with_non_utc_time_zone do
       it "returns direct messages created today" do
-        direct_message1 = create(:direct_message, created_at: Time.now.utc.beginning_of_day + 3.hours)
-        direct_message2 = create(:direct_message, created_at: Time.now.utc)
-        direct_message3 = create(:direct_message, created_at: Time.now.utc.end_of_day)
+        create(:direct_message, created_at: Date.current.beginning_of_day)
+        create(:direct_message, created_at: Time.current)
+        create(:direct_message, created_at: Date.current.end_of_day)
 
         expect(described_class.today.count).to eq 3
       end

spec/spec_helper.rb

@@ -104,6 +104,12 @@ RSpec.configure do |config|
     allow(Date).to receive(:today).and_return(Time.now.to_date)
   end
 
+  config.before(:each, :with_non_utc_time_zone) do
+    application_zone = ActiveSupport::TimeZone.new("Madrid")
+
+    allow(Time).to receive(:zone).and_return(application_zone)
+  end
+
   # Allows RSpec to persist some state between runs in order to support
   # the `--only-failures` and `--next-failure` CLI options.
   config.example_status_persistence_file_path = "spec/examples.txt"