Moves Age calculation to a module instead of monkeypatching Date

app/models/officing/residence.rb

@@ -68,7 +68,7 @@ class Officing::Residence
   end
 
   def allowed_age?
-    date_of_birth.age_in_years <= User.minimum_required_age
+    Age.in_years(date_of_birth) <= User.minimum_required_age
   end
 
   def geozone

app/models/user.rb

@@ -247,7 +247,7 @@ class User < ActiveRecord::Base
   end
 
   def age
-    date_of_birth.try(:age_in_years)
+    Age.in_years(date_of_birth)
   end
 
   def save_requiring_finish_signup

app/models/verification/management/document.rb

@@ -32,7 +32,7 @@ class Verification::Management::Document
   end
 
   def under_age?(response)
-    response.date_of_birth && User.minimum_required_age < response.date_of_birth.age_in_years
+    response.date_of_birth && User.minimum_required_age < Age.in_years(response.date_of_birth)
   end
 
   def verified?

app/models/verification/residence.rb

@@ -36,7 +36,7 @@ class Verification::Residence
 
   def allowed_age
     return if errors[:date_of_birth].any?
-    errors.add(:date_of_birth, I18n.t('verification.residence.new.error_not_allowed_age')) unless self.date_of_birth.age_in_years <= User.minimum_required_age
+    errors.add(:date_of_birth, I18n.t('verification.residence.new.error_not_allowed_age')) unless Age.in_years(self.date_of_birth) <= User.minimum_required_age
   end
 
   def document_number_uniqueness

config/initializers/age.rb

@@ -0,0 +1 @@
+require 'age'

config/initializers/date_ext.rb

@@ -1 +0,0 @@
-require 'date_ext'

lib/age.rb

@@ -0,0 +1,7 @@
+module Age
+  def self.in_years(dob, now = Time.now.utc.to_date)
+    return nil unless dob.present?
+    # reference: http://stackoverflow.com/questions/819263/get-persons-age-in-ruby#comment21200772_819263
+    now.year - dob.year - ((now.month > dob.month || (now.month == dob.month && now.day >= dob.day)) ? 0 : 1)
+  end
+end

lib/date_ext.rb

@@ -1,8 +0,0 @@
-module AgeInYears
-  def age_in_years(now = Time.now.utc.to_date)
-    # reference: http://stackoverflow.com/questions/819263/get-persons-age-in-ruby#comment21200772_819263
-    now.year - year - ((now.month > month || (now.month == month && now.day >= day)) ? 0 : 1)
-  end
-end
-
-Date.include(AgeInYears)

spec/lib/age_spec.rb

@@ -0,0 +1,58 @@
+require 'rails_helper'
+
+describe Age do
+  describe '.in_years' do
+    it "handles nils" do
+      expect(Age.in_years(nil)).to be_nil
+    end
+
+    it "calculates age correctly for common dates" do
+      d = Date.new(1980, 3, 13)
+      expect(Age.in_years(d, Date.new(2000, 3, 12))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000, 3, 13))).to eq(20)
+      expect(Age.in_years(d, Date.new(2000, 3, 14))).to eq(20)
+    end
+
+    it "calculates age correctly for people born near a year's limit" do
+      d = Date.new(1980, 12, 31)
+      expect(Age.in_years(d, Date.new(2000, 12, 30))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000, 12, 31))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  1,  1))).to eq(20)
+
+      d = Date.new(1980, 1, 1)
+      expect(Age.in_years(d, Date.new(2000, 12, 31))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  1,  1))).to eq(21)
+      expect(Age.in_years(d, Date.new(2001,  1,  2))).to eq(21)
+    end
+
+    it "calculates age correctly for people born around February the 29th" do
+      # 1980 and 2000 are leap years. 2001 is a regular year
+      d = Date.new(1980, 2, 29)
+      expect(Age.in_years(d, Date.new(2000,  2, 27))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000,  2, 28))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000,  2, 29))).to eq(20)
+      expect(Age.in_years(d, Date.new(2000,  3,  1))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  2, 27))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  2, 28))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  3,  1))).to eq(21)
+
+      d = Date.new(1980, 2, 28)
+      expect(Age.in_years(d, Date.new(2000,  2, 27))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000,  2, 28))).to eq(20)
+      expect(Age.in_years(d, Date.new(2000,  2, 29))).to eq(20)
+      expect(Age.in_years(d, Date.new(2000,  3,  1))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  2, 27))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  2, 28))).to eq(21)
+      expect(Age.in_years(d, Date.new(2001,  3,  1))).to eq(21)
+
+      d = Date.new(1980, 3, 1)
+      expect(Age.in_years(d, Date.new(2000,  2, 27))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000,  2, 28))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000,  2, 29))).to eq(19)
+      expect(Age.in_years(d, Date.new(2000,  3,  1))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  2, 27))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  2, 28))).to eq(20)
+      expect(Age.in_years(d, Date.new(2001,  3,  1))).to eq(21)
+    end
+  end
+end

spec/lib/date_spec.rb

@@ -1,55 +0,0 @@
-require 'rails_helper'
-
-describe Date do
-  describe '#age_in_years' do
-    it "calculates age correctly for common dates" do
-      d = Date.new(1980, 3, 13)
-      expect(d.age_in_years(Date.new(2000, 3, 12))).to eq(19)
-      expect(d.age_in_years(Date.new(2000, 3, 13))).to eq(20)
-      expect(d.age_in_years(Date.new(2000, 3, 14))).to eq(20)
-    end
-
-    it "calculates age correctly for people born near a year's limit" do
-      d = Date.new(1980, 12, 31)
-      expect(d.age_in_years(Date.new(2000, 12, 30))).to eq(19)
-      expect(d.age_in_years(Date.new(2000, 12, 31))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  1,  1))).to eq(20)
-
-      d = Date.new(1980, 1, 1)
-      expect(d.age_in_years(Date.new(2000, 12, 31))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  1,  1))).to eq(21)
-      expect(d.age_in_years(Date.new(2001,  1,  2))).to eq(21)
-    end
-
-    it "calculates age correctly for people born around February the 29th" do
-      # 1980 and 2000 are leap years. 2001 is a regular year
-      d = Date.new(1980, 2, 29)
-      expect(d.age_in_years(Date.new(2000,  2, 27))).to eq(19)
-      expect(d.age_in_years(Date.new(2000,  2, 28))).to eq(19)
-      expect(d.age_in_years(Date.new(2000,  2, 29))).to eq(20)
-      expect(d.age_in_years(Date.new(2000,  3,  1))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  2, 27))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  2, 28))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  3,  1))).to eq(21)
-
-      d = Date.new(1980, 2, 28)
-      expect(d.age_in_years(Date.new(2000,  2, 27))).to eq(19)
-      expect(d.age_in_years(Date.new(2000,  2, 28))).to eq(20)
-      expect(d.age_in_years(Date.new(2000,  2, 29))).to eq(20)
-      expect(d.age_in_years(Date.new(2000,  3,  1))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  2, 27))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  2, 28))).to eq(21)
-      expect(d.age_in_years(Date.new(2001,  3,  1))).to eq(21)
-
-      d = Date.new(1980, 3, 1)
-      expect(d.age_in_years(Date.new(2000,  2, 27))).to eq(19)
-      expect(d.age_in_years(Date.new(2000,  2, 28))).to eq(19)
-      expect(d.age_in_years(Date.new(2000,  2, 29))).to eq(19)
-      expect(d.age_in_years(Date.new(2000,  3,  1))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  2, 27))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  2, 28))).to eq(20)
-      expect(d.age_in_years(Date.new(2001,  3,  1))).to eq(21)
-    end
-
-  end
-end