circle.rb

class Circle
  def initialize(radius)
    @radius = radius
  end

  def perimeter
    (Math::PI * @radius * 2).round(3)
  end

  def area
    (Math::PI * @radius ** 2).round(3)
  end
end

rectangle.rb

class Rectangle
  def initialize(length, height)
    @length = length
    @height = height
  end

  def area
    @length * @height
  end

  def perimeter
    @length * 2 + @height * 2
  end
end

shapes_rspec.rb

require_relative 'shapes'
require_relative 'square'
require_relative 'rectangle'
require_relative 'circle'
require_relative 'triangle'
require_relative 'trapezoid'

require 'rspec'

describe Square do
  it 'calculates the squares area' do
    expect(Square.new(5).area).to eql(25)
  end

  it 'calculates the squares perimeter' do
    expect(Square.new(5).perimeter).to eql(20)
  end
end

describe Rectangle do
  it 'calculates the rectangles area' do
    expect(Rectangle.new(3,5).area).to eql(15)
  end
  it 'calculates the rectangles perimeter' do
    expect(Rectangle.new(3,5).perimeter).to eql(16)
  end
end

describe Circle do
  it 'calculates the circles perimeter' do
    expect(Circle.new(5).perimeter).to eql (31.416)
  end
  it 'calculates the circles area' do
    expect(Circle.new(5).area).to eql(78.54)
  end
end

describe Triangle do
  equilateral = { side: 5, length:3, breadth: 4 }
  sas = { angle: 28, length: 3, breadth: 4 }
  it 'calculates the equilateral triangles perimeter' do
    expect(Triangle.new(equilateral).perimeter).to eql(15)
  end
  it 'calculates the equilateral triangles area' do
    expect(Triangle.new(equilateral).area).to eql(6)
  end

  it 'calculates the sas triangle area' do
    expect(Triangle.new(sas).sas_area).to eql(1.62)
  end
  it 'calculates the sas triangle perimeter' do
    expect(Triangle.new(sas).sas_perimeter).to eql(11)
  end
end

describe Trapezoid do
  perimeter_arguments = { base1: 5, base2: 15, base3: 7, base4: 10 }
  area_arguments = { height: 10, base1: 5, base2: 8 }
  it 'calculates the trapezoids perimeter' do
    expect(Trapezoid.new(perimeter_arguments).perimeter).to eql(37)
  end
  it 'calculates the trapezoids area' do
    expect(Trapezoid.new(area_arguments).area).to eql(65)
  end
end

square.rb

class Square
  def initialize(side)
    @side = side
  end
  
  def area
    @side * @side
  end

  def perimeter
    @side * 4
  end
end

trapezoid.rb

class Trapezoid
  def initialize(arguments)
    @height = arguments[:height]
    @base1 = arguments[:base1]
    @base2 = arguments[:base2]
    @base3 = arguments[:base3]
    @base4 = arguments[:base4]
  end

  def area
    @height * (@base1 + @base2) / 2
  end

  def perimeter
    @base1 + @base2 + @base3 + @base4
  end
end

triangle.rb

class Triangle
  def initialize(arguments)
    @side = arguments[:side]
    @length = arguments[:length]
    @breadth = arguments[:breadth]
    @angle = arguments[:angle]
  end

  def perimeter
    @side * 3
  end

  def area
    @length * @breadth/2
  end

  def sas_area
    0.5 * @length * @breadth * Math::sin(@angle).round(2)
  end

  def sas_perimeter
      @length + @breadth * 2
  end
end