Allow Float#round to take a precision argument. Closes #8626 [norbert]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7401 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/lib/active_support/core_ext/float.rb

+require File.dirname(__FILE__) + '/float/rounding'
+
+class Float #:nodoc:
+  include ActiveSupport::CoreExtensions::Float::Rounding
+end

activesupport/lib/active_support/core_ext/float/rounding.rb

+module ActiveSupport #:nodoc:
+  module CoreExtensions #:nodoc:
+    module Float #:nodoc:
+      module Rounding
+        def self.included(base) #:nodoc:
+          base.send(:alias_method, :round_without_precision, :round)
+          base.send(:alias_method, :round, :round_with_precision)
+        end
+
+        # Rounds the float with the specified precision.
+        #
+        #   x = 1.337
+        #   x.round    # => 1
+        #   x.round(1) # => 1.3
+        #   x.round(2) # => 1.34
+        def round_with_precision(precision = nil)
+          precision.nil? ? round_without_precision : (self * (10 ** precision)).round / (10 ** precision).to_f
+        end
+      end
+    end
+  end
+end

activesupport/test/core_ext/float_ext_test.rb

+require File.dirname(__FILE__) + '/../abstract_unit'
+
+class FloatExtRoundingTests < Test::Unit::TestCase
+  def test_round_for_positive_number
+    assert_equal 1,    1.4.round
+    assert_equal 2,    1.6.round
+    assert_equal 2,    1.6.round(0)
+    assert_equal 1.4,  1.4.round(1)
+    assert_equal 1.4,  1.4.round(3)
+    assert_equal 1.5,  1.45.round(1)
+    assert_equal 1.45, 1.445.round(2)
+  end
+
+  def test_round_for_negative_number
+    assert_equal( -1,   -1.4.round )
+    assert_equal( -2,   -1.6.round )
+    assert_equal( -1.4, -1.4.round(1) )
+    assert_equal( -1.5, -1.45.round(1) )
+  end
+
+  def test_round_with_negative_precision
+    assert_equal 123460.0, 123456.0.round(-1)
+    assert_equal 123500.0, 123456.0.round(-2)
+  end
+end