diff --git a/lib/date_range.rb b/lib/date_range.rb
new file mode 100644
index 000000000..dac2a8fa9
--- /dev/null
+++ b/lib/date_range.rb
@@ -0,0 +1,39 @@
+module Hotel
+  class DateRange
+    attr_accessor :start_date, :end_date
+
+    def initialize(start_date, end_date)
+      if !(start_date.is_a? Date) || !(end_date.is_a? Date)
+        raise ArgumentError.new("If the start_date and end_date is not a Date")
+      end
+
+      if end_date < start_date
+        raise ArgumentError.new("If the start_date is biger then the end_date")
+      end
+
+      if start_date == end_date
+        raise ArgumentError.new("If the start_date date is same with end_date") 
+      end
+     
+      @start_date = start_date
+      @end_date = end_date
+    end
+
+    def ==(other)
+      start_date == other.start_date && end_date == other.end_date
+    end
+
+    def overlap?(other)
+      start_date < other.end_date && other.start_date < end_date
+    end
+
+    def include?(date)
+      start_date <= date && date < end_date
+    end
+
+    def calculate_nights
+      nights = (end_date - start_date).to_i
+      return nights
+    end 
+  end
+end
\ No newline at end of file
diff --git a/lib/hotel_controller.rb b/lib/hotel_controller.rb
new file mode 100644
index 000000000..1af905526
--- /dev/null
+++ b/lib/hotel_controller.rb
@@ -0,0 +1,71 @@
+require_relative "room"
+require_relative "date_range"
+require_relative "reservation"
+require_relative "no_room_available"
+
+
+module Hotel
+  class HotelController
+    attr_accessor :reservations
+    attr_reader :rooms
+
+    def initialize
+      @rooms = Array.new(20){|i| Hotel::Room.new(i+1)}
+      @reservations = []
+    end
+
+    #I can access the list of reservations for a specific date, so that I can track reservations by date
+    def reservation(date)
+      result = []
+      @reservations.each do |reservation|
+        if reservation.date_range.include?(date)
+          result << reservation
+        end
+      end
+      return result
+    end
+
+    # Cost for giving reservation
+    def total_cost(reservation)
+      total_cost = reservation.cost
+      return total_cost
+    end
+    
+    #Make new reservation
+    def reserve_room(start_date, end_date)
+      avalable_room = available_rooms(start_date, end_date)
+      raise NoRoomAvailable.new ("No room available") if avalable_room == []
+      
+      new_restervation = Hotel::Reservation.new(start_date, end_date, avalable_room.first)
+      reservations << new_restervation
+      return new_restervation
+    end
+
+    #I access the list of reservations for a specified room and a given date range
+    def reservations_for_room(date_range, room)
+      result = []
+      reservations.each do |reservation|
+        if reservation.date_range.overlap?(date_range) && room.room_nr == reservation.room.room_nr
+          result << reservation
+        end
+      end
+      return result
+    end
+
+    # Avalable rooms
+    def available_rooms(start_date, end_date)
+      unavalable_room = []
+      another_range = Hotel::DateRange.new(start_date, end_date)
+
+      @reservations.each do |reservation|
+        if reservation.date_range.overlap?(another_range) 
+          unavalable_room << reservation.room 
+        end
+      end 
+      
+      avalable_room = @rooms - unavalable_room
+      return avalable_room
+    end
+
+  end
+end
diff --git a/lib/no_room_available.rb b/lib/no_room_available.rb
new file mode 100644
index 000000000..37187aadd
--- /dev/null
+++ b/lib/no_room_available.rb
@@ -0,0 +1,4 @@
+module Hotel
+  class NoRoomAvailable < StandardError
+  end
+end
\ No newline at end of file
diff --git a/lib/reservation.rb b/lib/reservation.rb
new file mode 100644
index 000000000..d76a935a3
--- /dev/null
+++ b/lib/reservation.rb
@@ -0,0 +1,21 @@
+require_relative "date_range"
+require_relative "room"
+
+
+module Hotel
+  class Reservation
+   
+    # Feel free to change this method signature as needed. Make sure to update the tests!
+    attr_reader :id, :date_range, :room
+    def initialize(start_date, end_date, room)
+      @date_range = Hotel::DateRange.new(start_date, end_date)
+      @room = room
+    end
+
+    def cost
+      total = date_range.calculate_nights * 200.00
+      return total
+    end
+    
+  end
+end
\ No newline at end of file
diff --git a/lib/room.rb b/lib/room.rb
new file mode 100644
index 000000000..e74ca7f7f
--- /dev/null
+++ b/lib/room.rb
@@ -0,0 +1,15 @@
+
+module Hotel
+  class Room
+    attr_reader :room_nr, :cost 
+    def initialize(room_nr, cost = 200)
+      @room_nr = room_nr
+      @cost = cost 
+    end 
+  end
+
+  # def ==(other)
+  #   room_nr == other.room_nr
+  # end
+
+end
\ No newline at end of file
diff --git a/test/date_range_test.rb b/test/date_range_test.rb
new file mode 100644
index 000000000..85d554bcb
--- /dev/null
+++ b/test/date_range_test.rb
@@ -0,0 +1,170 @@
+require_relative "test_helper"
+
+describe Hotel::DateRange do
+
+  describe "consructor" do
+
+    it "Creates an instance of date_range" do
+      start_date = Date.new(2020, 01, 20)
+      end_date = Date.new(2020, 01, 25)
+      date_range = Hotel::DateRange.new(start_date, end_date)
+      date_range.must_be_kind_of Hotel::DateRange
+    end
+    
+    it "Keeps track of  start_date and end_date"  do
+      start_date = Date.today
+      end_date = start_date + 3
+
+      range = Hotel::DateRange.new(start_date, end_date)
+
+      expect(range).must_respond_to :start_date
+      expect(range.start_date).must_equal start_date
+      expect(range).must_respond_to :end_date
+      expect(range.end_date).must_equal end_date
+    end
+
+    it " Rais an argument ArgumentError if end_date is smaller then a start date" do
+      start_date = Date.today
+      end_date = Date.today - 3
+      expect{Hotel::DateRange.new(start_date, end_date)}.must_raise ArgumentError
+    end
+
+    it "is an an error for negative-lenght ranges" do
+      start_date = Date.today -5 
+      end_date = Date.today 
+      expect{Hotel::DateRange.new(start_date, end_date)}.must_raise ArgumentError
+      
+    end
+
+    it "is an error to create a 0-length range" do
+      start_date = Date.today
+      end_date = Date.today
+      expect{Hotel::DateRange.new(start_date, end_date)}.must_raise ArgumentError
+    end
+
+    it "is an error if the start and end date are not the Date" do
+      start_date = Date.today + 10
+      end_date = Date.today + 15
+      expect{Hotel::DateRange.new("2020/03/25", end_date)}.must_raise ArgumentError
+      expect{Hotel::DateRange.new(start_date, 20200325)}.must_raise ArgumentError
+    end
+  end
+
+  describe "==other" do
+    before do
+      start_date = Date.today + 5
+      end_date = start_date + 3
+      @range = Hotel::DateRange.new(start_date, end_date)
+    end
+    it "returne true if other start_date is not equal with start_date" do
+      start_date = @range.start_date
+      end_date = @range.end_date
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.==(test_range)).must_equal true
+    end
+
+    it "returne false if other start_date is not equal with start_date" do
+      start_date = Date.today 
+      end_date = Date.today + 3
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.==(test_range)).must_equal false
+    end
+  end
+
+  describe "overlap?" do
+    before do
+      start_date = Date.today + 5
+      end_date = start_date + 3
+      @range = Hotel::DateRange.new(start_date, end_date)
+    end
+    it "returns true for the same range" do
+      start_date = @range.start_date
+      end_date = @range.end_date
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal true
+    end
+    it "returns true for a contained range" do
+      start_date = Date.today + 3
+      end_date = start_date  + 9
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal true
+    end
+    it "returns true for a range that overlaps in front" do
+      start_date = Date.today + 3
+      end_date = start_date + 6
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal true
+    end
+    it "returns true for a range that overlaps in the back" do
+      start_date = Date.today +  6
+      end_date = start_date + 4
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal true
+    end
+    it "returns true for a containing range" do
+      start_date = Date.today + 6
+      end_date = start_date + 1
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal true
+    end
+    it "returns false for a range starting on the end_date date" do
+      start_date = Date.today + 8
+      end_date = start_date + 2
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal false
+    end
+    it "returns false for a range ending on the start_date date" do
+      start_date = Date.today + 1
+      end_date = start_date + 4
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal false
+    end
+    it "returns false for a range completely before" do
+      start_date = Date.today + 9
+      end_date = start_date + 3
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal false
+    end
+    it "returns false for a date completely after" do
+      start_date = Date.today + 1
+      end_date = start_date + 2
+      test_range = Hotel::DateRange.new(start_date, end_date)
+      expect(@range.overlap?(test_range)).must_equal false
+    end
+  end
+  
+
+  describe "include?" do
+    before do
+      start_date = Date.new(2017, 02, 15)
+      end_date = start_date + 3
+      @range = Hotel::DateRange.new(start_date, end_date)
+    end
+    it "reutrns false if the date is clearly out" do
+      date = Date.new(2017, 03, 15)
+      expect(@range.include?(date)).must_equal false
+    end
+
+    it "returns true for dates in the range" do
+      date = Date.new(2017, 02, 17)
+      expect(@range.include?(date)).must_equal true
+    end
+
+    it "returns false for the end_date date" do
+      date = Date.new(2017, 02, 18)
+      expect(@range.include?(date)).must_equal false
+    end
+  end
+
+  describe "calculate nights" do
+    it "returns the correct number of nights" do
+      start_date = Date.today
+      end_date = start_date + 3
+
+      range = Hotel::DateRange.new(start_date, end_date)
+
+      expect(range.calculate_nights).must_equal 3
+      expect(range.calculate_nights).must_be_kind_of Integer
+    end
+  end
+end
\ No newline at end of file
diff --git a/test/hotel_controller_test.rb b/test/hotel_controller_test.rb
new file mode 100644
index 000000000..d86b603ef
--- /dev/null
+++ b/test/hotel_controller_test.rb
@@ -0,0 +1,123 @@
+require_relative "test_helper"
+
+describe Hotel::HotelController do 
+  before do
+    @hotel_controller = Hotel::HotelController.new
+    @date = Date.parse("2020-08-04")
+    @rooms = Array.new(20){|i| Hotel::Room.new(i+1)}
+  end
+  describe "wave 1" do
+    describe "initializer" do
+      it "Creates an instance of hotel controler" do
+        @hotel_controller.must_be_kind_of Hotel::HotelController
+      end
+
+      it "create the rooms" do
+        rooms = @hotel_controller.rooms
+        expect(rooms).must_be_kind_of Array
+      end
+
+      it "create 20 rooms" do
+        rooms = @hotel_controller.rooms
+        expect(rooms.length).must_equal 20
+      end
+
+      it "create an empty array for reservatios" do
+        reservations = @hotel_controller.reservations
+        expect(reservations).must_equal []
+      end
+    end
+
+    describe "reservations" do
+      it "takes a Date and returns a list of Reservations" do
+        reservation_list = @hotel_controller.reservation(@date)
+        expect(reservation_list).must_be_kind_of Array
+        reservation_list.each do |res|
+          res.must_be_kind_of Hotel::Reservation
+        end
+      end
+    end
+
+    describe "total_cost" do
+      it "takes a reservation and returns the cost for that reservation" do
+        today = Date.today
+        room_one = @hotel_controller.rooms.first
+       
+        new_reservation = Hotel::Reservation.new(today + 6, today + 9, room_one)
+
+        total_cost_for_reservation = @hotel_controller.total_cost(new_reservation)
+        expect(total_cost_for_reservation).must_be_kind_of Numeric
+
+      end
+    end
+    
+
+    describe "reserve_room" do
+      it "takes two Date objects and returns a Reservation" do
+        today = Date.today
+
+        new_reservation = @hotel_controller.reserve_room(today + 6, today + 9)
+        expect(new_reservation).must_be_kind_of Hotel::Reservation
+      end
+
+      it "is an NoRoomAvalable if avalable_room is nil" do
+        start_date = Date.new(2020, 4, 10)
+        end_date = Date.new(2020, 4, 12)
+        room_number = 0
+        while room_number < 20 do
+          @hotel_controller.reserve_room(start_date, end_date)
+          room_number += 1
+        end
+
+        #avalable_room = @hotel_controller.reserve_room(start_date, end_date)
+        expect{(@hotel_controller.reserve_room(start_date, end_date))}.must_raise Hotel::NoRoomAvailable
+      end
+    end
+
+    describe "reservations_for" do
+      it "takes a date_range and room returns a list of Reservations" do
+        today = Date.today
+        room_one = Hotel::Room.new(1)
+        room_two = Hotel::Room.new(2)
+
+        reservation = Hotel::Reservation.new(today + 6, today + 9, room_one)
+
+        @hotel_controller.reservations = [
+          Hotel::Reservation.new(today + 1, today + 2, room_one),
+          Hotel::Reservation.new(today + 6, today + 9, room_two),
+          reservation,
+          Hotel::Reservation.new(today + 10, today + 13, room_one)
+        ]
+
+        reservation_list = @hotel_controller.reservations_for_room(Hotel::DateRange.new(today + 5, today + 9), room_one)
+        expect(reservation_list).must_be_kind_of Array
+        expect(reservation_list).must_equal [reservation] 
+
+      end
+    end
+        
+    describe "wave 2" do
+      describe "available_rooms" do
+        it "takes two dates and returns a list" do
+          start_date = Date.new(2020, 4, 10)
+          end_date = Date.new(2020, 4, 12)
+
+          room_one = @hotel_controller.rooms[0]
+          room_two = @hotel_controller.rooms[1]
+    
+          
+          @hotel_controller.reservations = [
+            Hotel::Reservation.new(start_date, end_date, room_one),
+            Hotel::Reservation.new(start_date, end_date, room_two),
+          ]
+
+          room_list = @hotel_controller.available_rooms(start_date + 1 , end_date + 1)
+
+          expect(room_list).must_be_kind_of Array
+          expect(room_list.length).must_equal 18
+          expect(room_list[-1].room_nr).must_equal 20
+        end
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/test/reservation_test.rb b/test/reservation_test.rb
new file mode 100644
index 000000000..cb0cc280c
--- /dev/null
+++ b/test/reservation_test.rb
@@ -0,0 +1,36 @@
+require_relative "test_helper"
+
+describe Hotel::Reservation do
+  describe "consructor" do
+    
+    it "Creates an instance of reservation" do
+      reservation = Hotel::Reservation.new(Date.today, Date.today + 1, Hotel::Room.new(1))
+      reservation.must_be_kind_of Hotel::Reservation
+    end
+
+    it "Keeps track of date_range" do
+      start_date = Date.today
+      end_date = Date.today + 1
+      date_range = Hotel::DateRange.new(start_date, end_date)
+  
+      reservation = Hotel::Reservation.new(start_date, end_date, Hotel::Room.new(1))
+      reservation.must_respond_to :date_range
+      reservation.date_range.must_equal date_range
+    end
+
+  end
+  
+  describe "cost" do
+    it "returns a number" do
+      start_date = Date.today
+      end_date = start_date + 3
+      room = Hotel::Room.new(1, 200)
+
+      @reservation = Hotel::Reservation.new(start_date, end_date, room)
+      
+      expect(@reservation.cost).must_be_kind_of Numeric
+      expect(@reservation.cost).must_equal 600
+    end
+  end
+
+end
\ No newline at end of file
diff --git a/test/test_helper.rb b/test/test_helper.rb
index c3a7695cf..93fef04f8 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,8 +1,21 @@
 # Add simplecov
+require 'simplecov'
+SimpleCov.start do
+  add_filter 'test/' # Tests should not be checked for coverage.
+end
+
 require "minitest"
 require "minitest/autorun"
 require "minitest/reporters"
+require "minitest/skip_dsl"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
 # require_relative your lib files here!
+require_relative "../lib/hotel_controller.rb"
+require_relative "../lib/reservation.rb"
+require_relative "../lib/date_range.rb"
+require_relative "../lib/room.rb"
+require_relative "../lib/no_room_available.rb"
+
+
diff --git a/test/test_room.rb b/test/test_room.rb
new file mode 100644
index 000000000..fb2cd7771
--- /dev/null
+++ b/test/test_room.rb
@@ -0,0 +1,26 @@
+require_relative "test_helper"
+
+
+describe Hotel::Room do
+  describe "consructor" do
+    
+    it "Creates an instance of room" do
+      room = Hotel::Room.new(1, 200)
+      room.must_be_kind_of Hotel::Room
+    end
+
+    it "Keeps track of room nr" do
+      room_nr = 1
+      room = Hotel::Room.new(room_nr, 200)
+      room.must_respond_to :room_nr
+      room.room_nr.must_equal room_nr
+    end
+    
+    it "Keeps track of cost" do
+      cost = 200
+      room = Hotel::Room.new(1, cost)
+      room.must_respond_to :cost
+      room.cost.must_equal cost
+    end
+  end
+end