All the little details

spec/factories/employee_shift_factory.rb

@@ -0,0 +1,4 @@
+FactoryGirl.define do
+  factory :employee_shift do
+  end
+end

spec/models/employee_shift_spec.rb

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+require 'spec_helper'
+
+describe EmployeeShift do
+  describe '.for_supplier' do
+    it 'returns the proper employee shifts' do
+      supplier1 = create :supplier
+      supplier2 = create :supplier
+      es1 = create :employee_shift, supplier: supplier1, start_from: 9.days.ago, end_on: 5.days.ago
+      es2 = create :employee_shift, supplier: supplier2, start_from: 9.days.ago, end_on: 5.days.ago
+      es3 = create :employee_shift, supplier: supplier2, start_from: 9.days.ago, end_on: 8.days.ago
+      es4 = create :employee_shift, supplier: supplier2, start_from: 1.day.from_now, end_on: 1.day.from_now + 2.hours
+      es5 = create :employee_shift, supplier: supplier2, end_on: 1.day.from_now
+
+      results = EmployeeShift.for_supplier(supplier2)
+      results.should_not include(es1), 'different supplier'
+      results.should include(es2), 'end day within a week ago'
+      results.should_not include(es3), 'end day more than a week ago'
+      results.should include(es4)     , 'Most relevant case'
+      results.should_not include(es5) , 'missing start_from'
+    end
+  end
+end