Russell's Airport Challenge

lib/airport.rb

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+require_relative 'plane'
+require_relative 'weather'
+
+class Airport
+  DEFAULT_CAPACITY = 1
+
+  attr_reader :capacity
+
+  def initialize(capacity = DEFAULT_CAPACITY)
+    @airport = []
+    @capacity = capacity
+  end
+
+  def land(plane)
+    fail 'Airport full' if full?
+    fail "Flight cannot land due to stormy weather" if bad_weather?
+    airport << plane
+  end
+
+  def take_off(*)
+    fail "Flight cancelled due to bad weather" if bad_weather?
+    @airport.pop
+  end
+
+  def bad_weather?
+    weather.stormy?
+  end
+
+  def weather
+    @weather ||= Weather.new
+  end
+
+  private
+
+  attr_reader :airport
+
+  def full?
+    airport.count >= capacity
+  end
+end

lib/plane.rb

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+class Plane
+
+end

lib/weather.rb

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+
+class Weather
+
+  def stormy?
+    forecast >= 6
+  end
+
+  private
+
+  def forecast
+    rand(10)
+  end
+end

spec/airport_spec.rb

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+require 'airport'
+require 'weather'
+
+describe Airport do
+
+  describe '#land' do
+
+    it 'instructs a plane to land at an airport' do
+
+      # User story 1
+      # As an air traffic controller 
+      # So I can get passengers to a destination 
+      # I want to instruct a plane to land at an airport
+
+      # Arrange
+      airport = Airport.new
+      plane = Plane.new
+      # Act / Assert
+      expect { airport.land(plane) }.not_to raise_error
+    end
+
+    it 'prevents a plane from landing when airport is full' do
+
+      # User story 3
+      # As an air traffic controller 
+      # To ensure safety 
+      # I want to prevent landing when the airport is full 
+
+      subject.capacity.times { subject.land Plane.new }
+      expect { subject.land Plane.new }.to raise_error 'Airport full'
+    end
+
+    it 'does not allow planes to land with stormy weather' do
+
+      # User story 6
+      # As an air traffic controller
+      # To ensure safety
+      # I want to prevent landing when weather is stormy 
+
+      # Arrange
+      airport = Airport.new
+      stormy_weather = Weather.new
+      plane = Plane.new
+
+      # Act / Assert
+
+      allow(stormy_weather).to receive(:stormy?) { true }
+      allow(airport).to receive(:weather) { stormy_weather }
+
+      expect { airport.land(plane) }.to raise_error "Flight cannot land due to stormy weather"
+    end
+
+  end
+
+  describe '#take_off' do
+
+    it 'instructs a plane to take off and report it is not in the airport' do
+
+      # User Story 2
+      # As an air traffic controller 
+      # So I can get passengers on the way to their destination 
+      # I want to instruct a plane to take off from an airport and confirm that it is no longer in the airport
+
+      # Arrange
+      airport = Airport.new
+      plane = Plane.new
+
+      # Act / Assert
+      expect(subject.take_off).to eq 'Plane no longer in airport'
+    end
+
+    it 'prevents take off when weather is stormy' do
+
+      # User story 5
+      # As an air traffic controller 
+      # To ensure safety 
+      # I want to prevent takeoff when weather is stormy 
+
+      # Arrange
+      airport = Airport.new
+      stormy_weather = Weather.new
+      plane = Plane.new
+
+      # Act / Assert
+
+      allow(stormy_weather).to receive(:stormy?) { true }
+      allow(airport).to receive(:weather) { stormy_weather }
+
+      expect { airport.take_off(plane) }.to raise_error "Flight cancelled due to bad weather"
+    end
+
+  end
+
+  it 'has a default airport capacity that can be overidden' do
+
+    # User story 4
+    # As the system designer
+    # So that the software can be used for many different airports
+    # I would like a default airport capacity that can be overridden as appropriate
+
+    expect(subject.capacity).to eq Airport::DEFAULT_CAPACITY
+  end
+
+  describe 'initialization' do
+    subject { Airport.new }
+    let(:plane) { Plane.new }
+    it 'defaults capacity' do
+      described_class::DEFAULT_CAPACITY.times do
+        subject.land(plane)
+      end
+      expect { subject.land(plane) }.to raise_error 'Airport full'
+    end
+  end
+end