Email professors on email change

app/models/professor.rb

@@ -4,7 +4,7 @@ class Professor < ActiveRecord::Base
   EMAIL_REGEX = /\A\w+\z/
 
   before_create { self.identifier = new_professor_identifier }
-  before_save { email.downcase! }
+  before_save { email.downcase!; email_changed }
   has_many :positions
   validate :static_identifier, on: :update
   validates_presence_of :name
@@ -20,4 +20,10 @@ def to_param
     def static_identifier
       errors[:identifier] = "can't be changed" if self.identifier_changed?
     end
+
+    def email_changed
+      return unless self.persisted?
+      return if self.email.downcase == self.email_was.downcase
+      ProfessorMailer.pending_recommendation(self).deliver
+    end
 end

config/environments/test.rb

@@ -30,6 +30,9 @@
   # The :test delivery method accumulates sent emails in the
   # ActionMailer::Base.deliveries array.
   config.action_mailer.delivery_method = :test
+  config.action_mailer.default_url_options = {
+    host: 'localhost:3000'
+  }
 
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr

spec/models/professor_spec.rb

@@ -3,6 +3,9 @@
 describe Professor do
   before { @prof = FactoryGirl.create(:professor) }
   subject { @prof }
+  after(:each) do
+    ActionMailer::Base.deliveries.clear
+  end
 
   it { should respond_to(:name) }
   it { should respond_to(:email) }
@@ -32,4 +35,36 @@
     before { @prof.identifier = 'abc' }
     it { should_not be_valid }
   end
+
+  describe 'changing professor emails' do
+    context 'email changed' do
+      before do
+        @prof.email = @prof.email + 'a'
+        @prof.save!
+      end
+
+      it 'should send an email' do
+        ActionMailer::Base.deliveries.count.should == 1
+      end
+    end
+
+    context 'unchanged email' do
+      before { @prof.save! }
+
+      it 'should not send an email' do
+        ActionMailer::Base.deliveries.count.should == 0
+      end
+    end
+
+    context 'email case changed' do
+      before do
+        @prof.email = @prof.email.upcase
+        @prof.save!
+      end
+
+      it 'should not send an email' do
+        ActionMailer::Base.deliveries.count.should == 0
+      end
+    end
+  end
 end