Merge pull request #474 from Shopify/infinity-and-beyond

correctly handle Float::INFINITY

Author: elfassy

lib/money/money.rb

@@ -126,6 +126,10 @@ def new_from_money(amount, currency)
 
   def initialize(value, currency)
     raise ArgumentError if value.nan?
+    if value.infinite?
+      Money.deprecate("Initializing Money with infinity is deprecated and will raise an ArgumentError in v4")
+    end
+
     @currency = Helpers.value_to_currency(currency)
     @value = BigDecimal(value.round(@currency.minor_units))
     freeze
@@ -153,9 +157,14 @@ def -@
   end
 
   def <=>(other)
-    return unless other.respond_to?(:to_money)
-    arithmetic(other) do |money|
-      value <=> money.value
+    if other.is_a?(Numeric)
+      return value <=> other
+    end
+
+    if other.respond_to?(:to_money)
+      arithmetic(other) do |money|
+        value <=> money.value
+      end
     end
   end
 

spec/money_spec.rb

@@ -457,6 +457,16 @@
     expect { Money.new( 0.0 / 0) }.to raise_error(ArgumentError)
   end
 
+  it "raises when constructed with positive infinity" do
+    expect(Money).to receive(:deprecate).once
+    Money.new(Float::INFINITY)
+  end
+
+  it "raises when constructed with negative infinity" do
+    expect(Money).to receive(:deprecate).once
+    Money.new(-Float::INFINITY)
+  end
+
   it "is comparable with non-money objects" do
     expect(money).not_to eq(nil)
   end
@@ -548,6 +558,7 @@
     let (:nil_10) { Money.new(10.00, Money::NULL_CURRENCY) }
     let (:nil_20) { Money.new(20.00, Money::NULL_CURRENCY) }
     let (:usd_10) { Money.new(10.00, 'USD') }
+    let (:jpy_10) { Money.new(10, 'JPY') }
 
     it "<=> can compare with and without currency" do
       expect(Money.new(1000, Money::NULL_CURRENCY) <=> Money.new(2000, 'JPY')).to eq(-1)
@@ -680,6 +691,32 @@
       it { expect { cad_10 <= nil }.to(raise_error(ArgumentError)) }
       it { expect { cad_10 <  nil }.to(raise_error(ArgumentError)) }
     end
+
+    describe('infinity comparisons') do
+      it { expect(cad_10 <=> Float::INFINITY).to(eq(-1)) }
+      it { expect(cad_10 <  Float::INFINITY).to(eq(true)) }
+      it { expect(cad_10 <= Float::INFINITY).to(eq(true)) }
+      it { expect(cad_10 >  Float::INFINITY).to(eq(false)) }
+      it { expect(cad_10 >= Float::INFINITY).to(eq(false)) }
+
+      it { expect(cad_10 <=> -Float::INFINITY).to(eq(1)) }
+      it { expect(cad_10 >  -Float::INFINITY).to(eq(true)) }
+      it { expect(cad_10 >= -Float::INFINITY).to(eq(true)) }
+      it { expect(cad_10 <  -Float::INFINITY).to(eq(false)) }
+      it { expect(cad_10 <= -Float::INFINITY).to(eq(false)) }
+
+      it { expect(jpy_10 <=> Float::INFINITY).to(eq(-1)) }
+      it { expect(jpy_10 <  Float::INFINITY).to(eq(true)) }
+      it { expect(jpy_10 <= Float::INFINITY).to(eq(true)) }
+      it { expect(jpy_10 >  Float::INFINITY).to(eq(false)) }
+      it { expect(jpy_10 >= Float::INFINITY).to(eq(false)) }
+
+      it { expect(jpy_10 <=> -Float::INFINITY).to(eq(1)) }
+      it { expect(jpy_10 >  -Float::INFINITY).to(eq(true)) }
+      it { expect(jpy_10 >= -Float::INFINITY).to(eq(true)) }
+      it { expect(jpy_10 <  -Float::INFINITY).to(eq(false)) }
+      it { expect(jpy_10 <= -Float::INFINITY).to(eq(false)) }
+    end
   end
 
   describe "#subunits" do