Implement fixed array

source/fixed_array.rb

@@ -1,3 +1,27 @@
 class FixedArray
 
+  def initialize(size)
+    @array = Array.new(size)
+    return @array
+  end
+
+  def get(index)
+    check_bounds(index)
+    @array[index]
+  end
+
+  def set(index, element)
+    check_bounds(index)
+    @array[index] = element
+  end
+
+  private
+  def check_bounds(index)
+    raise OutOfBoundsException, "Index #{index} not in array" if index < 0 || index >= @array.size
+  end
+
+  class OutOfBoundsException < RangeError
+  end
+
 end
+

source/fixed_array_spec.rb

@@ -1,5 +1,40 @@
 require_relative 'fixed_array'
 
 describe FixedArray do
+
+    describe "#set" do
+      let(:array) {FixedArray.new(5)}
+
+    it "changes the value at the selected index" do
+      array.set(2, 4)
+      values = array.instance_variable_get(:@array)
+      expect(values[2]).to eq 4
+    end
+
+    it "raises an error if the index is outside the array" do
+      expect { array.set(5, 2)}.to raise_error(RangeError)
+      expect { array.set(-2, 2)}.to raise_error(RangeError)
+    end  
+
+  end
 
+  describe "#get" do
+    before(:each) do
+      @array = FixedArray.new(5)
+      @array.set(2,2)
+    end
+
+    it "returns the value at the chosen index" do
+      expect(@array.get(2)).to eq 2
+    end
+
+    it "raises an error if an index outside the array is given" do
+      expect { @array.get(5)}.to raise_error(RangeError)
+      expect { @array.get(-1)}.to raise_error(RangeError)
+    end
+
+  end
+
+
+
 end