Merge pull request #295 from timcraft/integer-upto

spec/core/integer/upto_spec.rb

@@ -0,0 +1,69 @@
+require_relative '../../spec_helper'
+
+describe "Integer#upto [stop] when self and stop are Integers" do
+  it "does not yield when stop is less than self" do
+    result = []
+    5.upto(4) { |x| result << x }
+    result.should == []
+  end
+
+  it "yields once when stop equals self" do
+    result = []
+    5.upto(5) { |x| result << x }
+    result.should == [5]
+  end
+
+  it "yields while increasing self until it is less than stop" do
+    result = []
+    2.upto(5) { |x| result << x }
+    result.should == [2, 3, 4, 5]
+  end
+
+  it "yields while increasing self until it is greater than floor of a Float endpoint" do
+    result = []
+    9.upto(13.3) {|i| result << i}
+    -5.upto(-1.3) {|i| result << i}
+    result.should == [9,10,11,12,13,-5,-4,-3,-2]
+  end
+
+  it "raises an ArgumentError for non-numeric endpoints" do
+    -> { 1.upto("A") {|x| p x} }.should raise_error(ArgumentError)
+    -> { 1.upto(nil) {|x| p x} }.should raise_error(ArgumentError)
+  end
+
+  describe "when no block is given" do
+    it "returns an Enumerator" do
+      result = []
+
+      enum = 2.upto(5)
+      enum.each { |i| result << i }
+
+      result.should == [2, 3, 4, 5]
+    end
+
+    describe "returned Enumerator" do
+      describe "size" do
+        it "raises an ArgumentError for non-numeric endpoints" do
+          enum = 1.upto("A")
+          -> { enum.size }.should raise_error(ArgumentError)
+          enum = 1.upto(nil)
+          -> { enum.size }.should raise_error(ArgumentError)
+        end
+
+        it "returns stop - self + 1" do
+          5.upto(10).size.should == 6
+          1.upto(10).size.should == 10
+          0.upto(10).size.should == 11
+          0.upto(0).size.should == 1
+          -5.upto(-3).size.should == 3
+        end
+
+        it "returns 0 when stop < self" do
+          5.upto(4).size.should == 0
+          0.upto(-5).size.should == 0
+          -3.upto(-5).size.should == 0
+        end
+      end
+    end
+  end
+end

src/integer.rb

@@ -11,6 +11,18 @@ def downto(n)
     end
   end
 
+  def upto(n)
+    unless block_given?
+      return enum_for(:upto, n) { self <= n ? (n - self + 1) : 0 }
+    end
+
+    i = self
+    until i > n
+      yield i
+      i += 1
+    end
+  end
+
   def allbits?(mask)
     unless mask.respond_to?(:to_int)
       raise TypeError, "No implicit conversion of #{mask.class} into Integer"