1 files changed, 84 insertions, 0 deletions
diff --git a/spec/ruby/library/bigdecimal/remainder_spec.rb b/spec/ruby/library/bigdecimal/remainder_spec.rb
new file mode 100644
index 0000000000..796522c5c8
--- /dev/null
+++ b/spec/ruby/library/bigdecimal/remainder_spec.rb
@@ -0,0 +1,84 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+require 'bigdecimal'
+
+describe "BigDecimal#remainder" do
+
+  before :each do
+    @zero = BigDecimal("0")
+    @one = BigDecimal("0")
+    @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")
+  end
+
+  it "it equals modulo, if both values are of same sign" do
+    BigDecimal('1234567890123456789012345679').remainder(BigDecimal('1')).should == @zero
+    BigDecimal('123456789').remainder(BigDecimal('333333333333333333333333333E-50')).should == BigDecimal('0.12233333333333333333345679E-24')
+
+    @mixed.remainder(@pos_frac).should == @mixed % @pos_frac
+    @pos_int.remainder(@pos_frac).should == @pos_int % @pos_frac
+    @neg_frac.remainder(@neg_int).should == @neg_frac % @neg_int
+    @neg_int.remainder(@neg_frac).should == @neg_int % @neg_frac
+  end
+
+  it "means self-arg*(self/arg).truncate" do
+    @mixed.remainder(@neg_frac).should == @mixed - @neg_frac * (@mixed / @neg_frac).truncate
+    @pos_int.remainder(@neg_frac).should == @pos_int - @neg_frac * (@pos_int / @neg_frac).truncate
+    @neg_frac.remainder(@pos_int).should == @neg_frac - @pos_int * (@neg_frac / @pos_int).truncate
+    @neg_int.remainder(@pos_frac).should == @neg_int - @pos_frac * (@neg_int / @pos_frac).truncate
+  end
+
+  it "returns NaN used with zero" do
+    @mixed.remainder(@zero).nan?.should == true
+    @zero.remainder(@zero).nan?.should == true
+  end
+
+  it "returns zero if used on zero" do
+    @zero.remainder(@mixed).should == @zero
+  end
+
+  it "returns NaN if NaN is involved" do
+    @nan.remainder(@nan).nan?.should == true
+    @nan.remainder(@one).nan?.should == true
+    @one.remainder(@nan).nan?.should == true
+    @infinity.remainder(@nan).nan?.should == true
+    @nan.remainder(@infinity).nan?.should == true
+  end
+
+  it "returns NaN if Infinity is involved" do
+    @infinity.remainder(@infinity).nan?.should == true
+    @infinity.remainder(@one).nan?.should == true
+    @infinity.remainder(@mixed).nan?.should == true
+    @infinity.remainder(@one_minus).nan?.should == true
+    @infinity.remainder(@frac_1).nan?.should == true
+    @one.remainder(@infinity).nan?.should == true
+
+    @infinity_minus.remainder(@infinity_minus).nan?.should == true
+    @infinity_minus.remainder(@one).nan?.should == true
+    @one.remainder(@infinity_minus).nan?.should == true
+    @frac_2.remainder(@infinity_minus).nan?.should == true
+
+    @infinity.remainder(@infinity_minus).nan?.should == true
+    @infinity_minus.remainder(@infinity).nan?.should == true
+  end
+
+  it "coerces arguments to BigDecimal if possible" do
+    @one.remainder(2).should == @one
+  end
+
+
+  it "raises TypeError if the argument cannot be coerced to BigDecimal" do
+    lambda {
+      @one.remainder('2')
+    }.should raise_error(TypeError)
+  end
+
+end