Replace Method with Method Object.

replace-method-with-method-object/lib/after.rb

@@ -0,0 +1,47 @@
+class TaxAlgorithm
+  def initialize(income: nil, expenses: 0, type: :dependent_worker)
+    @income = income
+    @expenses = expenses
+    @type = type
+
+    @return_value = 0
+    @number_of_people_under_roof = 1 
+  end
+
+  def compute
+    process_type
+    process_number_of_people
+    process_income_expense_difference
+    deduct_expenses
+  end
+
+  def process_type
+    if @type == :dependent_worker
+      @return_value += @income * 0.02
+    else
+      @return_value += @income * 0.04
+    end
+  end
+
+  def process_number_of_people
+    @return_value *= 1.10 if @number_of_people_under_roof > 2
+  end
+
+  def process_income_expense_difference
+    @return_value += @expenses * 0.05 if @income - @expenses > @income * 0.05
+  end
+
+  def deduct_expenses
+    @return_value -= @expenses * 0.30
+  end
+end
+
+class TaxSimulator
+  def initialize person
+    @person = person
+  end
+
+  def simulate_return(income: nil, expenses: 0, type: :dependent_worker)
+    TaxAlgorithm.new(income: income, expenses: expenses, type: type).compute
+  end
+end

replace-method-with-method-object/lib/before.rb

@@ -0,0 +1,26 @@
+class TaxSimulator
+  def initialize person
+    @person = person
+  end
+
+  def simulate_return(income: nil, expenses: 0, type: :dependent_worker)
+    return_value = 0
+    number_of_people_under_roof = 1 
+
+    if type == :dependent_worker
+      return_value += income * 0.02
+    else
+      return_value += income * 0.04
+    end
+
+    if number_of_people_under_roof > 2
+      return_value *= 1.10
+    end
+
+    if income - expenses > income * 0.05
+      return_value += expenses * 0.05
+    end
+
+    return_value -= expenses * 0.30
+  end
+end

replace-method-with-method-object/test/test.rb

@@ -1,5 +1,15 @@
-require 'minitest/spec'
 require 'minitest/autorun'
+require 'minitest/spec'
 
 require 'before' if ENV["BEFORE"]
 require 'after' unless ENV["BEFORE"]
+
+describe TaxSimulator do
+  it "simulates tax returns" do
+    TaxSimulator.new("Jose Mota").simulate_return(
+      income: 10000,
+      expenses: 300,
+      type: :independent_worker
+    ).must_equal 325.0
+  end
+end