diff --git a/Rakefile b/Rakefile
index 0c2d13fe8..3319583aa 100644
--- a/Rakefile
+++ b/Rakefile
@@ -3,7 +3,7 @@ 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/*_spec.rb']
 end
 
 task default: :test
diff --git a/lib/calendar.rb b/lib/calendar.rb
new file mode 100644
index 000000000..f1004897a
--- /dev/null
+++ b/lib/calendar.rb
@@ -0,0 +1,111 @@
+require 'date'
+require_relative 'reservation'
+require_relative 'calendar_date'
+require_relative 'room'
+
+class Calendar
+  attr_accessor :all_reservations_store, :date_store
+  
+  def initialize
+    @date_store = {}
+    @all_reservations_store = []
+  end
+
+
+  def make_reservation(start_date, end_date)
+    reservation = Reservation.new(start_date, end_date)
+
+    return reservation
+  end
+
+
+  def list_available_rooms_entire_stay(reservation)
+    date_range = []
+    available_rooms_all_dates = []
+
+
+    if (reservation.total_nights == 1) && (@date_store[(reservation.start_date).iso8601].all_available_rooms.length == 20)
+      available_rooms = [1]
+      return available_rooms
+    end
+
+    (reservation.total_nights).times do |i|
+      if @date_store[(reservation.start_date + i).iso8601].nil?
+        date = CalendarDate.new
+      else
+        raise NoRoomsError.new "There are no rooms available for the duration of this stay." if @date_store[(reservation.start_date + i).iso8601].unavailable?
+        date_range << (@date_store[(reservation.start_date + i).iso8601]).all_available_rooms
+      end
+
+    end
+
+
+    date_range.each do |i|
+      if (date_range[0] & date_range[i]).any?
+        available_rooms_all_dates << (date_range[0] & date_range[i])
+      end
+    end
+
+    raise NoRoomsError.new "There are no rooms available for the duration of this stay." if available_rooms_all_dates.empty?   
+
+    available_rooms = available_rooms_all_dates.flatten.uniq!
+
+    return available_rooms
+  end
+
+
+  def is_available?(room_number, date)
+    date = Date.parse(date).iso8601
+    return @date_store[date].room_available?(room_number)
+  end
+
+
+  def reservations_on_date(date)
+    date = Date.parse(date).iso8601
+    return @date_store[date].reservations
+  end
+
+
+  def rooms_on_date(date)
+    date = Date.parse(date).iso8601
+    if @date_store[date].nil?
+      date = CalendarDate.new
+    else
+      date = @date_store[date]
+    end
+
+    raise NoRoomError.new("There are no available rooms on the specified date.") if date.unavailable?
+
+    return date.all_available_rooms 
+  end
+
+
+  def find_by_id(reservation_id)
+    reservation = @all_reservations_store.find { |reservation| reservation[:id] == reservation_id}
+    raise NoReservationError.new("There is no existing reservation with given ID.") if reservation == nil
+    
+    return reservation
+  end
+
+
+  def total_cost_reservation(reservation_id)
+    reservation = find_by_id(reservation_id)
+    return reservation[:cost]
+  end
+
+
+  def add_to_calendar(reservation)
+    @all_reservations_store << reservation.details
+
+    reservation.total_nights.times do |i|
+      if !@date_store.key?(reservation.start_date)
+        date = CalendarDate.new
+        date.add_reservation(reservation)
+        @date_store[(reservation.start_date + i).iso8601] = date
+      else
+        @date_store[(reservation.start_date + i).iso8601].add_reservation(reservation)
+        raise NoRoomError.new "Sorry, there is no availability on that date." if @date_store[(reservation.start_date + i).iso8601].unavailable?
+      end
+    end
+  end
+end
\ No newline at end of file
diff --git a/lib/calendar_date.rb b/lib/calendar_date.rb
new file mode 100644
index 000000000..4c09a1c64
--- /dev/null
+++ b/lib/calendar_date.rb
@@ -0,0 +1,41 @@
+require 'date'
+
+require_relative 'room'
+require_relative 'reservation'
+
+class CalendarDate
+  attr_accessor :day_reservation_store, :available_rooms
+  
+  def initialize
+    @day_reservation_store = []
+    @available_rooms = Rooms.new
+  end
+
+  def reservations 
+    return @day_reservation_store
+  end
+
+
+  def unavailable?
+    return @day_reservation_store.length == 20 
+  end
+
+
+  def room_available?(room_number)
+    return @available_rooms.rooms.include?(room_number)
+  end
+
+
+  def all_available_rooms
+    return @available_rooms.rooms
+  end
+
+  
+  def add_reservation(reservation)
+    @day_reservation_store << reservation.details
+    @available_rooms.room_reserved(reservation.room_number)
+
+    return @day_reservation_store
+  end
+
+end
\ No newline at end of file
diff --git a/lib/reservation.rb b/lib/reservation.rb
new file mode 100644
index 000000000..0b39576b1
--- /dev/null
+++ b/lib/reservation.rb
@@ -0,0 +1,48 @@
+require 'date'
+require 'securerandom'
+
+require_relative 'room'
+
+
+class Reservation
+  attr_accessor :id, :start_date, :end_date, :total_nights, :cost, :room_number
+
+  def initialize(start_date, end_date)
+    @id = (SecureRandom.alphanumeric).slice(0...7).upcase
+    @start_date = Date.parse(start_date)
+    @end_date = Date.parse(end_date)
+    @total_nights = (@end_date - @start_date).to_i
+    @cost = @total_nights * 200
+    @room_number = room_number
+
+    def valid_date?(date)
+      date_format = '%Y-%m-%d'
+      DateTime.strptime(date, date_format)
+      true
+    rescue ArgumentError
+      false
+    end
+
+    valid_date?(start_date)
+    valid_date?(end_date)
+
+    raise InvalidDateRangeError.new ("The given date range is invalid.") if (@end_date - @start_date) <= 0
+  end
+
+  def assign_room_number
+    room_number = available_rooms[0]
+    return room_number
+  end
+  
+  def details
+   {
+      :id => @id,
+      :start_date => @start_date.iso8601, 
+      :end_date => @end_date.iso8601, 
+      :total_nights => @total_nights,
+      :cost => @cost,
+      :room_number => @room_number
+    }
+  end
+
+end
\ No newline at end of file
diff --git a/lib/room.rb b/lib/room.rb
new file mode 100644
index 000000000..8053fe62c
--- /dev/null
+++ b/lib/room.rb
@@ -0,0 +1,20 @@
+require 'date'
+
+class Rooms
+  attr_accessor :all_rooms
+
+  def initialize
+    @all_rooms = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+  end
+
+
+  def room_reserved(room_number)
+    @all_rooms.delete(room_number)
+  end
+
+
+  def rooms
+    @all_rooms
+  end
+
+end
\ No newline at end of file
diff --git a/test/calendar_date_spec.rb b/test/calendar_date_spec.rb
new file mode 100644
index 000000000..089c00e21
--- /dev/null
+++ b/test/calendar_date_spec.rb
@@ -0,0 +1,22 @@
+require_relative 'test_helper'
+
+describe "Manages calendar and it's various duties" do
+  before do 
+    @reservation1 = Reservation.new("2020/05/04", "2020/05/07")
+    @reservation2 = Reservation.new("2020/05/07", "2020/05/09")
+    @reservation3 = Reservation.new("2020/05/06", "2020/05/11")
+
+    @calendar = Calendar.new
+    
+    @calendar.add_to_calendar(@reservation1)
+    @calendar.add_to_calendar(@reservation2)
+    @calendar.add_to_calendar(@reservation3)
+  end
+
+  it "has an array that keeps track of the available rooms" do
+    
+    hopefully_an_array = @date_store[Date.parse("2020/05/04").iso8601].all_available_rooms
+
+    expect hopefully_an_array.must_be_instance_of Array
+  end
+end
\ No newline at end of file
diff --git a/test/calendar_spec.rb b/test/calendar_spec.rb
new file mode 100644
index 000000000..6587847ba
--- /dev/null
+++ b/test/calendar_spec.rb
@@ -0,0 +1,82 @@
+require_relative 'test_helper'
+
+
+describe "Manages calendar and it's various duties" do
+  before do 
+    @reservation1 = Reservation.new("2020/05/04", "2020/05/07")
+    @reservation2 = Reservation.new("2020/05/07", "2020/05/09")
+    @reservation3 = Reservation.new("2020/05/06", "2020/05/11")
+
+    @calendar = Calendar.new
+    @calendar.add_to_calendar(@reservation1)
+    @calendar.add_to_calendar(@reservation2)
+    @calendar.add_to_calendar(@reservation3)
+
+    
+    # puts "\n"
+    # puts @calendar.date_store
+    # puts "\n"
+    
+  end
+
+  it "gives correct cost of requested reservation" do
+    reservation1 = @reservation1.details
+    id = reservation1[:id]
+    cost = @calendar.total_cost_reservation(id)
+
+    expect (reservation1[:cost]).must_equal cost
+  end
+
+  it "lists all reservations for specific date" do
+    reservation1 = @reservation1.details
+    expected_outcome = [reservation1]
+    actual_outcome = @calendar.reservations_on_date("2020/05/04")
+    assert_equal(actual_outcome, expected_outcome)
+  end 
+
+  it "accesses list of available rooms on a given date" do
+    expected_outcome = [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+    actual_outcome = @calendar.rooms_on_date("2020/05/04")
+    assert_equal(actual_outcome, expected_outcome)
+  end
+
+  it "returns an array of all 1-20 rooms if there are no reservations on a given date" do
+    expected_outcome = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20]
+    actual_outcome = @calendar.rooms_on_date("2020/05/02")
+    assert_equal(actual_outcome, expected_outcome)
+  end
+
+  it "returns an array of the open rooms during a date range" do
+    @calendar.list_available_rooms_entire_stay(@reservation2)
+    expect available_rooms.must_be_instance_of Array
+  end
+
+  # it "raises NoRoomError if all rooms on a given date are booked" do
+    
+  #   raise NoRoomError
+  # end
+
+  it 'accesses correct reservation when searching by id' do
+    reservation1 = @reservation1.details
+    id = reservation1[:id]
+
+    expected_outcome = reservation1
+    actual_outcome = @calendar.find_by_id(id)
+    assert_equal(actual_outcome, expected_outcome)
+  end
+
+  it 'creates a new reservation' do
+    expected_outcome = Reservation.new("2020/05/04", "2020/05/07")
+    actual_outcome = expected_outcome
+
+    assert_equal(actual_outcome, expected_outcome)
+  end
+
+  it "returns true/false if given room is available on a given date" do
+    yesorno = @calendar.is_available?(5, "2020/05/07")
+
+    expect yesorno.must_equal true
+  end
+
+end
+    
diff --git a/test/reservation_spec.rb b/test/reservation_spec.rb
new file mode 100644
index 000000000..e69de29bb
diff --git a/test/room_spec.rb b/test/room_spec.rb
new file mode 100644
index 000000000..e69de29bb
diff --git a/test/test_helper.rb b/test/test_helper.rb
index c3a7695cf..80aa07bde 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -1,8 +1,11 @@
-# Add simplecov
+require 'simplecov'
 require "minitest"
 require "minitest/autorun"
 require "minitest/reporters"
 
 Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new
 
-# require_relative your lib files here!
+require_relative '../lib/calendar'
+require_relative '../lib/reservation'
+require_relative '../lib/room'
+require_relative '../lib/calendar_date'