Use new unsubscribed_at attribute for more accuracy and simplicity

Currently we work out when someone unsubscribed by looking at
updated_at time for unsubscribed alerts. This might not always be
accurate. It's also adds extra unexpected behaviour for us to understand
and maintain.

This commit swaps that calculation out and instead simply uses the new
unsubscribed_at attribute.

Also adds a factory for unsubscribed alerts.

app/models/alert.rb

@@ -56,9 +56,9 @@ def self.count_of_new_unique_email_created_on_date(date)
   end
 
   def self.count_of_email_completely_unsubscribed_on_date(date)
-    emails = where("date(updated_at) = ?", date).where(unsubscribed: true).
-                                                 distinct.
-                                                 pluck(:email)
+    emails = where("date(unsubscribed_at) = ?", date).where(unsubscribed: true).
+                                                      distinct.
+                                                      pluck(:email)
 
     emails.reject do |email|
       active.where(email: email).where("date(created_at) <= ?", date).any?

spec/controllers/performance_controller_spec.rb

@@ -49,7 +49,7 @@
       before do
         alert = create :confirmed_alert, email: "mary@example.org", created_at: DateTime.new(2016,6,19)
 
-        Timecop.freeze(Time.utc(2016, 8, 23)) { alert.update_attribute(:unsubscribed, true) }
+        Timecop.freeze(Time.utc(2016, 8, 23)) { alert.unsubscribe! }
 
         get(:alerts, format: :json)
       end

spec/factories.rb

@@ -101,6 +101,11 @@
     factory :confirmed_alert do
       confirmed true
       confirm_id "1234"
+
+      factory :unsubscribed_alert do
+        unsubscribed true
+        unsubscribed_at Time.now
+      end
     end
   end
 

spec/models/alert_spec.rb

@@ -237,7 +237,7 @@
         end
 
         Timecop.freeze(Date.new(2016, 8, 24)) do
-          a.update_attribute(:unsubscribed, true)
+          a.unsubscribe!
         end
 
         a
@@ -255,16 +255,16 @@
     end
 
     it "is 0 when there is no complete unsubscribes" do
-      create(:confirmed_alert, email: "foo@email.com", unsubscribed: true)
-      create(:confirmed_alert, email: "foo@email.com", unsubscribed: true)
-      create(:confirmed_alert, email: "foo@email.com", unsubscribed: false)
+      create(:unsubscribed_alert, email: "foo@email.com")
+      create(:unsubscribed_alert, email: "foo@email.com")
+      create(:confirmed_alert, email: "foo@email.com")
 
       expect(Alert.count_of_email_completely_unsubscribed_on_date(Date.today)).to eql 0
     end
 
     it "only counts unique emails" do
-      create(:confirmed_alert, email: "foo@email.com", unsubscribed: true)
-      create(:confirmed_alert, email: "foo@email.com", unsubscribed: true)
+      create(:unsubscribed_alert, email: "foo@email.com")
+      create(:unsubscribed_alert, email: "foo@email.com")
 
       expect(Alert.count_of_email_completely_unsubscribed_on_date(Date.today)).to eql 1
     end
@@ -273,8 +273,8 @@
       alert1 = create(:confirmed_alert, email: "foo@email.com")
       alert2 = create(:confirmed_alert, email: "bar@email.com")
 
-      Timecop.freeze(Time.utc(2016, 8, 23)) { alert1.update_attribute(:unsubscribed, true) }
-      Timecop.freeze(Time.utc(2016, 8, 24)) { alert2.update_attribute(:unsubscribed, true) }
+      Timecop.freeze(Time.utc(2016, 8, 23)) { alert1.unsubscribe! }
+      Timecop.freeze(Time.utc(2016, 8, 24)) { alert2.unsubscribe! }
 
       expect(Alert.count_of_email_completely_unsubscribed_on_date(Date.new(2016, 8, 23))).to eql 1
     end
@@ -285,7 +285,7 @@
           create(:confirmed_alert, email: "foo@email.com")
         end
 
-        Timecop.freeze(Time.utc(2016, 8, 23)) { alert.update_attribute(:unsubscribed, true) }
+        Timecop.freeze(Time.utc(2016, 8, 23)) { alert.unsubscribe! }
 
         Timecop.freeze(Time.utc(2016, 8, 28)) do
           create(:confirmed_alert, email: "foo@email.com")
@@ -302,7 +302,7 @@
             create(:confirmed_alert, email: "foo@email.com")
           end
 
-          Timecop.freeze(Time.utc(2016, 9, 1)) { alert.update_attribute(:unsubscribed, true) }
+          Timecop.freeze(Time.utc(2016, 9, 1)) { alert.unsubscribe! }
         end
 
         it "doesn't count their unsubscribe" do