Add Rational#as_percentage_of method

readysteady · Oct 22, 2024 · b373c7b · b373c7b
1 parent 48a6605
commit b373c7b
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diff --git a/lib/percentage.rb b/lib/percentage.rb
@@ -150,6 +150,10 @@ def to_percentage
   def percent_of(n)
     n * Percentage(self)
   end
+
+  def as_percentage_of(n)
+    Percentage.new(self / n)
+  end
 end
 
 class BigDecimal

diff --git a/spec/percentage_spec.rb b/spec/percentage_spec.rb
@@ -480,6 +480,15 @@
       expect(Rational(90).percent_of(Rational(150, 2))).to eq(Rational(135, 2))
     end
   end
+
+  describe '#as_percentage_of' do
+    it 'returns a percentage object with the value of the decimal divided by the argument' do
+      percentage = Rational(50).as_percentage_of(Rational(100))
+
+      expect(percentage).to be_a(Percentage)
+      expect(percentage.value).to eq(Rational(1, 2))
+    end
+  end
 end
 
 RSpec.describe BigDecimal do