diff --git a/.gitignore b/.gitignore
index 5e1422c9c..2b42312c5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,7 +9,8 @@
 /test/tmp/
 /test/version_tmp/
 /tmp/
-
+.vscode/
+.DS_Store
 # Used by dotenv library to load environment variables.
 # .env
 
diff --git a/Rakefile b/Rakefile
index 0c2d13fe8..8aebe3bda 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1,9 +1,9 @@
-require 'rake/testtask'
+require "rake/testtask"
 
 Rake::TestTask.new do |t|
   t.libs = ["lib"]
   t.warning = true
-  t.test_files = FileList['test/*_test.rb']
+  t.test_files = FileList["test/*_test.rb"]
 end
 
 task default: :test
diff --git a/lib/date_range.rb b/lib/date_range.rb
new file mode 100644
index 000000000..7048dc2db
--- /dev/null
+++ b/lib/date_range.rb
@@ -0,0 +1,35 @@
+class DateRange
+  attr_reader :start_date, :end_date
+
+  def initialize(start_date_str, end_date_str) # give it Date.parse(year-month)
+    @start_date = Date.parse(start_date_str)
+    @end_date = Date.parse(end_date_str)
+  end
+
+  def with_in_range?(date)
+    return date >= start_date && date < end_date
+  end
+
+  def duration
+    # to get duration subtract the two dates
+    return end_date - start_date
+  end
+
+  def self.overlap?(date_range1, date_range2)
+    if date_range1.end_date <= date_range2.start_date || date_range1.start_date >= date_range2.end_date
+      return false
+    else
+      return true
+    end
+    # if date_range1.start_date <= date_range2.start_date && date_range1.end_date >= date_range2.end_date
+    #   return true
+    # elsif date_range1.start_date < date_range2.end_date && date_range1.start_date >= date_range2.start_date
+    #   return true
+    # elsif date_range1.end_date >date_range2.start_date && date_range1.end_date <= date_range2.end_date
+    #   return true
+    # else
+    #   return false
+    # end
+
+  end
+end
diff --git a/lib/reservation.rb b/lib/reservation.rb
new file mode 100644
index 000000000..d9850c4f0
--- /dev/null
+++ b/lib/reservation.rb
@@ -0,0 +1,30 @@
+# creating reservation class
+require_relative "system.rb"
+
+module Hotel
+  class Reservation
+    attr_reader :date_range, :room_num, :cost_per_night
+
+    def initialize(date_range, room_num)
+      @date_range = date_range
+      @room_num = room_num
+      @cost_per_night = 200
+    end
+
+    def get_cost
+      return date_range.duration * cost_per_night
+    end
+
+    # to get the total cost, need the duration (as input wont be able to dirctly get duration but will get res id)
+    # go throught the reservation array to get one one rervation which matches the id
+    # get that reservation_id to get the duration
+    # after getting duration, calculate cost
+
+    #  found_reservation = @reservations.find do |reservation|
+    #   reservation.reservation_id == reservation_id
+    #  end
+
+    # duration = found_reservation.date_range.duration()
+
+  end
+end
diff --git a/lib/room.rb b/lib/room.rb
new file mode 100644
index 000000000..8b1378917
--- /dev/null
+++ b/lib/room.rb
@@ -0,0 +1 @@
+
diff --git a/lib/system.rb b/lib/system.rb
new file mode 100644
index 000000000..53fbe54e8
--- /dev/null
+++ b/lib/system.rb
@@ -0,0 +1,74 @@
+require "date"
+require "pry"
+require_relative "room.rb"
+require_relative "reservation.rb"
+require_relative "date_range.rb"
+
+module Hotel
+  class System
+    attr_reader :reservations, :rooms
+
+    def initialize(number_of_rooms)
+      @reservations = []
+      @rooms = (1..number_of_rooms).to_a
+    end
+
+    def create_reservation(start_date, end_date)
+      date_range = DateRange.new(start_date, end_date)
+      room = find_avail_room(date_range)
+   
+      if !room
+        raise "there is no available room"
+      end
+      reservation = Reservation.new(date_range, room)
+      reservations << reservation
+    end
+
+    #helper method
+    def find_avail_room(date_range)
+      rooms.each do |room|
+        room_reservation = reservations.select { |reservation| reservation.room_num == room }
+        if !room_reservation.any? { |reservation| DateRange.overlap?(reservation.date_range, date_range) }
+          return room
+        end
+      end
+      return
+    end
+
+    def get_reservation(room_num, given_date_range)
+      room_reservations = reservations.select { |res| res.room_num = room_num }
+      return room_reservations.select { |res| DateRange.overlap?(res.date_range, given_date_range) }
+    end
+
+    def search_by_date(date)
+      return reservations.select { |reservation| reservation.date_range.with_in_range?(date) }
+    end
+  end
+end
+
+# 1) Write pseudocode
+# 2) Write test(s)
+# 3) Write code
+# 4) Refactor
+# 5) Commit (15 of them)
+
+# WAVE 1
+# write the functionality for the system to track valid reservations
+# Your job is to only build the classes that store information and handle business logic
+
+# I can access the list of all of the rooms in the hotel (done)
+# I access the list of reservations for a specified room and a given date range (change the date using parse method)(done)
+
+# I can access the list of reservations for a specific date, so that I can track reservations by date
+
+# I can get the total cost for a given reservation
+
+# I want exception raised when an invalid date range is provided, so that I can't make a reservation for an invalid date range
+
+# Detail
+
+# When reserving a room, the user provides only the start and end dates
+# the library should determine which room to use for the reservation
+# For this wave, any room can be reserved at any time, and you don't need to check whether reservations conflict with each other (this will come in wave 2!)
+
+# WAVE 2
diff --git a/test/date_range_test.rb b/test/date_range_test.rb
new file mode 100644
index 000000000..e209547f9
--- /dev/null
+++ b/test/date_range_test.rb
@@ -0,0 +1,116 @@
+# writting a test for duration
+require_relative "test_helper"
+
+describe "date range class" do
+  it "calculates duration" do
+    # Arrange
+    date_range_instance = DateRange.new("2020-02-27", "2020-03-02")
+    # Act
+
+    duration = date_range_instance.duration()
+
+    # Assert
+    expect (duration).must_equal 4
+  end
+  describe "overlap" do
+    it "case 1 " do
+      #Arrange
+      date_one = DateRange.new("2020-03-27", "2020-04-02")
+      date_two = DateRange.new("2020-04-04", "2020-04-06")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(false)
+    end
+    it "case 2" do
+      #Arrange
+      date_one = DateRange.new("2020-03-27", "2020-04-02")
+      date_two = DateRange.new("2020-04-02", "2020-04-03")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(false)
+    end
+    it "case 3" do
+      #Arrange
+      date_one = DateRange.new("2020-03-27", "2020-04-02")
+      date_two = DateRange.new("2020-04-01", "2020-04-27")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 4" do
+      #Arrange
+      date_one = DateRange.new("2020-03-27", "2020-04-02")
+      date_two = DateRange.new("2020-03-27", "2020-04-02")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 5" do
+      #Arrange
+      date_one = DateRange.new("2020-03-27", "2020-04-02")
+      date_two = DateRange.new("2020-03-27", "2020-04-05")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 6" do
+      #Arrange
+      date_one = DateRange.new("2020-03-17", "2020-04-05")
+      date_two = DateRange.new("2020-03-06", "2020-04-05")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 7" do
+      #Arrange
+      date_one = DateRange.new("2020-04-03", "2020-04-07")
+      date_two = DateRange.new("2020-04-04", "2020-04-05")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 8" do
+      #Arrange
+      date_one = DateRange.new("2020-04-03", "2020-04-05")
+      date_two = DateRange.new("2020-03-31", "2020-04-07")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 9" do
+      #Arrange
+      date_one = DateRange.new("2020-03-17", "2020-04-05")
+      date_two = DateRange.new("2020-03-06", "2020-03-17")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(false)
+    end
+    it "case 10" do
+      #Arrange
+      date_one = DateRange.new("2020-03-17", "2020-04-05")
+      date_two = DateRange.new("2020-03-06", "2020-03-19")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(true)
+    end
+    it "case 11" do
+      #Arrange
+      date_one = DateRange.new("2020-05-05", "2020-05-07")
+      date_two = DateRange.new("2020-03-06", "2020-03-17")
+      #Act
+      result = DateRange.overlap?(date_one, date_two)
+      #Assert
+      expect(result).must_equal(false)
+    end
+  end
+end
diff --git a/test/reservation_test.rb b/test/reservation_test.rb
new file mode 100644
index 000000000..fafd4117a
--- /dev/null
+++ b/test/reservation_test.rb
@@ -0,0 +1,18 @@
+require "simplecov"
+SimpleCov.start
+
+require_relative "test_helper"
+
+describe "Reservation class" do
+  it "calculate cost" do
+    #Arrange
+    date_range = DateRange.new("02-10-2020", "02-12-2020")
+    reservation = Hotel::Reservation.new(date_range, 8)
+
+    #Act
+    cost = reservation.get_cost
+
+    #Assert
+    expect(cost).must_equal(date_range.duration * reservation.cost_per_night)
+  end
+end
diff --git a/test/room_test.rb b/test/room_test.rb
new file mode 100644
index 000000000..2ffef0c00
--- /dev/null
+++ b/test/room_test.rb
@@ -0,0 +1,2 @@
+require "simplecov"
+SimpleCov.start
diff --git a/test/system_test.rb b/test/system_test.rb
new file mode 100644
index 000000000..07a46ada1
--- /dev/null
+++ b/test/system_test.rb
@@ -0,0 +1,53 @@
+require "date"
+
+require "simplecov"
+SimpleCov.start
+
+require_relative "test_helper"
+
+describe "System class" do
+  it "gets lists of rooms" do
+    #Arrange
+    system = Hotel::System.new(20)
+
+    #Act
+    rooms = system.rooms
+
+    #Assert
+    expect(rooms).must_equal (1..20).to_a
+  end
+
+  it "create reservation" do
+    #Arrange
+    system = Hotel::System.new(20)
+    #Act
+    system.create_reservation("01/01/2020", "01/10/2020")
+    #Assert
+    expect(system.reservations.length).must_equal 1
+  end
+
+  it "gets list of reservation and given a date" do
+    #Arrange
+    date = Date.parse ("02/02/2020")
+    system = Hotel::System.new(20)
+    system.create_reservation("03/12/2020", "03/12/2020")
+    system.create_reservation("02/02/2020", "02/04/2020")
+
+    #Act
+    res_array = system.search_by_date(date)
+
+    #Assert
+    expect(res_array.length).must_equal 1
+  end
+
+  it "raises exception, if no available rooms" do
+    #Arrange
+    system = Hotel::System.new(1)
+    system.create_reservation("03/03/2010", "03/04/2020")
+    #Act
+    expect{system.create_reservation("03/03/2010", "03/04/2020")}.must_raise Exception
+    #Assert
+  end
+
+  
+end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index c3a7695cf..b5c1dc51b 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,8 +1,15 @@
-# 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"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
-# require_relative your lib files here!
+require_relative "../lib/date_range.rb"
+require_relative "../lib/reservation.rb"
+require_relative "../lib/system.rb"
+require_relative "../lib/room.rb"