Explaining variable exercise

Author: mxie

.gitignore

@@ -0,0 +1,7 @@
+!.keep
+*.DS_Store
+*.swo
+*.swp
+.bundle
+tags
+vendor

Gemfile

@@ -0,0 +1,4 @@
+source 'https://rubygems.org'
+
+gem 'rake'
+gem 'rspec'

Gemfile.lock

@@ -0,0 +1,24 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    diff-lcs (1.2.5)
+    rake (10.3.2)
+    rspec (3.1.0)
+      rspec-core (~> 3.1.0)
+      rspec-expectations (~> 3.1.0)
+      rspec-mocks (~> 3.1.0)
+    rspec-core (3.1.7)
+      rspec-support (~> 3.1.0)
+    rspec-expectations (3.1.2)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.1.0)
+    rspec-mocks (3.1.3)
+      rspec-support (~> 3.1.0)
+    rspec-support (3.1.2)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  rake
+  rspec

Rakefile

@@ -0,0 +1,7 @@
+#!/usr/bin/env rake
+
+require 'rspec/core/rake_task'
+
+RSpec::Core::RakeTask.new(:spec)
+
+task default: :spec

bin/setup

@@ -0,0 +1,10 @@
+#!/usr/bin/env sh
+
+# Run this script immediately after cloning the codebase.
+# https://github.com/thoughtbot/guides/tree/master/protocol
+
+# Exit if any subcommand fails
+set -e
+
+# Set up Ruby dependencies via Bundler
+bundle install

lib/tipper.rb

@@ -0,0 +1,17 @@
+class Tipper
+  TAX = 0.05
+
+  def initialize(amount:, discount_percentage: 0, tip_percentage:)
+    @amount = amount
+    @discount_percentage = discount_percentage
+    @tip_percentage = tip_percentage
+  end
+
+  def total
+    amount + (amount * TAX) - (amount * (discount_percentage / 100.0)) + (amount * (tip_percentage / 100.0))
+  end
+
+  private
+
+  attr_reader :amount, :discount_percentage, :tip_percentage
+end

spec/lib/tipper_spec.rb

@@ -0,0 +1,15 @@
+require 'spec_helper'
+
+describe Tipper do
+  describe '#total' do
+    it 'returns the total due with tax and tip' do
+      tipper = Tipper.new(amount: 100, tip_percentage: 20)
+      expect(tipper.total).to eq 125
+    end
+
+    it 'returns the total due with tax, discount, and tip' do
+      tipper = Tipper.new(amount: 100, discount_percentage: 20, tip_percentage: 20)
+      expect(tipper.total).to eq 105
+    end
+  end
+end

spec/spec_helper.rb

@@ -0,0 +1,5 @@
+PROJECT_ROOT = File.expand_path("../..", __FILE__)
+
+Dir.glob(File.join(PROJECT_ROOT, "lib", "*.rb")).each do |file|
+  require file
+end