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diff --git a/spec/rubyspec/library/bigdecimal/divmod_spec.rb b/spec/rubyspec/library/bigdecimal/divmod_spec.rb
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+++ b/spec/rubyspec/library/bigdecimal/divmod_spec.rb
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+require File.expand_path('../../../spec_helper', __FILE__)
+require File.expand_path('../shared/modulo', __FILE__)
+require 'bigdecimal'
+
+module DivmodSpecs
+  def self.check_both_nan(array)
+    array.length.should == 2
+    array[0].nan?.should == true
+    array[1].nan?.should == true
+  end
+  def self.check_both_bigdecimal(array)
+    array.length.should == 2
+    array[0].kind_of?(BigDecimal).should == true
+    array[1].kind_of?(BigDecimal).should == true
+  end
+end
+
+# TODO: figure out a way to do the shared specs with helpers instead
+# of spec'ing a method that does not really exist
+describe "BigDecimal#mod_part_of_divmod" do
+  # BigDecimal#divmod[1] behaves exactly like #modulo
+  before :all do
+    class BigDecimal
+      def mod_part_of_divmod(arg)
+        divmod(arg)[1]
+      end
+    end
+  end
+
+  after :all do
+    class BigDecimal
+      undef mod_part_of_divmod
+    end
+  end
+
+  it_behaves_like :bigdecimal_modulo, :mod_part_of_divmod
+
+  it "raises ZeroDivisionError if other is zero" do
+    bd5667 = BigDecimal.new("5667.19")
+
+    lambda { bd5667.send(@method, 0) }.should raise_error(ZeroDivisionError)
+    lambda { bd5667.send(@method, BigDecimal("0")) }.should raise_error(ZeroDivisionError)
+    lambda { @zero.send(@method, @zero) }.should raise_error(ZeroDivisionError)
+  end
+end
+
+describe "BigDecimal#divmod" do
+
+  before :each do
+    @a = BigDecimal("42.00000000000000000001")
+
+    @zero = BigDecimal("0")
+    @zero_pos = BigDecimal("+0")
+    @zero_neg = BigDecimal("-0")
+
+    @one = BigDecimal("1")
+    @mixed = BigDecimal("1.23456789")
+    @pos_int = BigDecimal("2E5555")
+    @neg_int = BigDecimal("-2E5555")
+    @pos_frac = BigDecimal("2E-9999")
+    @neg_frac = BigDecimal("-2E-9999")
+    @nan = BigDecimal("NaN")
+    @infinity = BigDecimal("Infinity")
+    @infinity_minus = BigDecimal("-Infinity")
+    @one_minus = BigDecimal("-1")
+    @frac_1 = BigDecimal("1E-99999")
+    @frac_2 = BigDecimal("0.9E-99999")
+
+    @special_vals = [@infinity, @infinity_minus, @nan]
+    @regular_vals = [
+      @one, @mixed, @pos_int, @neg_int, @pos_frac,
+      @neg_frac, @one_minus, @frac_1, @frac_2]
+    @zeroes = [@zero, @zero_pos, @zero_neg]
+  end
+
+  it "divides value, returns an array" do
+    res = @a.divmod(5)
+    res.kind_of?(Array).should == true
+  end
+
+  it "array contains quotient and modulus as BigDecimal" do
+    res = @a.divmod(5)
+    DivmodSpecs.check_both_bigdecimal(res)
+    res[0].should == BigDecimal('0.8E1')
+    res[1].should == BigDecimal('2.00000000000000000001')
+
+    BigDecimal('1').divmod(BigDecimal('2')).should == [0, 1]
+    BigDecimal('2').divmod(BigDecimal('1')).should == [2, 0]
+
+    BigDecimal('1').divmod(BigDecimal('-2')).should == [-1, -1]
+    BigDecimal('2').divmod(BigDecimal('-1')).should == [-2, 0]
+
+    BigDecimal('-1').divmod(BigDecimal('2')).should == [-1, 1]
+    BigDecimal('-2').divmod(BigDecimal('1')).should == [-2, 0]
+  end
+
+  it "can be reversed with * and +" do
+    # Example taken from BigDecimal documentation
+    a = BigDecimal.new("42")
+    b = BigDecimal.new("9")
+    q, m = a.divmod(b)
+    c = q * b + m
+    a.should == c
+
+    values = [@one, @one_minus, BigDecimal('2'), BigDecimal('-2'),
+      BigDecimal('5'), BigDecimal('-5'), BigDecimal('10'), BigDecimal('-10'),
+      BigDecimal('20'), BigDecimal('-20'), BigDecimal('100'), BigDecimal('-100'),
+      BigDecimal('1.23456789E10'), BigDecimal('-1.23456789E10')
+    ]
+
+    # TODO: file MRI bug:
+    # BigDecimal('1').divmod(BigDecimal('3E-9'))[0] #=> 0.3E9,
+    # but really should be 0.333333333E9
+    values << BigDecimal('1E-10')
+    values << BigDecimal('-1E-10')
+    values << BigDecimal('2E55')
+    values << BigDecimal('-2E55')
+    values << BigDecimal('2E-5555')
+    values << BigDecimal('-2E-5555')
+
+
+    values_and_zeroes = values + @zeroes
+    values_and_zeroes.each do |val1|
+      values.each do |val2|
+        res = val1.divmod(val2)
+        DivmodSpecs.check_both_bigdecimal(res)
+        res[0].should == ((val1/val2).floor)
+        res[1].should == (val1 - res[0] * val2)
+      end
+    end
+  end
+
+  it "returns an array of two NaNs if NaN is involved" do
+    (@special_vals + @regular_vals + @zeroes).each do |val|
+      DivmodSpecs.check_both_nan(val.divmod(@nan))
+      DivmodSpecs.check_both_nan(@nan.divmod(val))
+    end
+  end
+
+  it "raises ZeroDivisionError if the divisor is zero" do
+    (@special_vals + @regular_vals + @zeroes - [@nan]).each do |val|
+      @zeroes.each do |zero|
+        lambda { val.divmod(zero) }.should raise_error(ZeroDivisionError)
+      end
+    end
+  end
+
+  it "returns an array of Infinity and NaN if the dividend is Infinity" do
+    @regular_vals.each do |val|
+      array = @infinity.divmod(val)
+      array.length.should == 2
+      array[0].infinite?.should == (val > 0 ? 1 : -1)
+      array[1].nan?.should == true
+    end
+  end
+
+  it "returns an array of zero and the dividend if the divisor is Infinity" do
+    @regular_vals.each do |val|
+      array = val.divmod(@infinity)
+      array.length.should == 2
+      array[0].should == @zero
+      array[1].should == val
+    end
+  end
+
+  it "returns an array of two zero if the diviend is zero" do
+    @zeroes.each do |zero|
+      @regular_vals.each do |val|
+        zero.divmod(val).should == [@zero, @zero]
+      end
+    end
+  end
+
+  it "raises TypeError if the argument cannot be coerced to BigDecimal" do
+    lambda {
+      @one.divmod('1')
+    }.should raise_error(TypeError)
+  end
+
+end