Validate that lines don't start and end at the same spot.

Fixed #61.

app/models/interstate_line.rb

@@ -12,6 +12,8 @@ class InterstateLine < ActiveRecord::Base
   validates :incoming_state, :presence => true
   validates :outgoing_state, :presence => true
   validates :operating_level, :presence => true
+  validates_with LineEndpointValidator, :start => :incoming_state,
+      :end => :outgoing_state
 
   attr_readonly :incoming_state, :outgoing_state, :line_type
 

app/models/line.rb

@@ -10,4 +10,5 @@ class Line < TechnicalComponentInstance
   validates :line_type, :presence => true
   validates :city, :presence => true
   validates :other_city, :presence => true
+  validates_with LineEndpointValidator, :start => :city, :end => :other_city
 end

app/validators/line_endpoint_validator.rb

@@ -0,0 +1,9 @@
+class LineEndpointValidator < ActiveModel::Validator
+  def validate record
+    starting = record.send(options[:start])
+    ending = record.send(options[:end])
+    if starting and ending and starting == ending
+      record.errors[:base] << "start and endpoint cannot be the same"
+    end
+  end
+end

spec/models/interstate_line_spec.rb

@@ -12,7 +12,7 @@
   it { should validate_presence_of :operating_level }
 
   context "an instance of InterstateLine" do
-    before :all do
+    before do
       @line = Factory :interstate_line
     end
 
@@ -37,5 +37,12 @@
 
       lambda { @line.accepted = false }.should raise_error
     end
+
+    it "should validate that the incoming and outgoing states are different" do
+      line = Factory.build :interstate_line
+      line.incoming_state = @line.incoming_state
+      line.outgoing_state = line.incoming_state
+      line.save.should raise_error
+    end
   end
 end

spec/models/line_spec.rb

@@ -8,4 +8,15 @@
   it { should validate_presence_of :line_type }
 
   it { should have_many :repairs }
+
+  context "an instance of Line" do
+    before :all do
+      @line = Factory :line
+    end
+
+    it "should validate that the incoming and outgoing states are different" do
+      @line.other_city = @line.city
+      @line.save.should raise_error
+    end
+  end
 end