1 files changed, 77 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
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+++ b/spec/ruby/library/bigdecimal/remainder_spec.rb
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+require_relative '../../spec_helper'
+require 'bigdecimal'
+
+describe "BigDecimal#remainder" do
+
+  before :each do
+    @zero = BigDecimal("0")
+    @one = BigDecimal("1")
+    @three = BigDecimal("3")
+    @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
+
+  version_is BigDecimal::VERSION, "3.3.0" do
+    it "raises ZeroDivisionError used with zero" do
+      -> { @mixed.remainder(@zero) }.should.raise(ZeroDivisionError)
+      -> { @zero.remainder(@zero) }.should.raise(ZeroDivisionError)
+    end
+  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).should.nan?
+    @nan.remainder(@one).should.nan?
+    @one.remainder(@nan).should.nan?
+    @infinity.remainder(@nan).should.nan?
+    @nan.remainder(@infinity).should.nan?
+  end
+
+  it "coerces arguments to BigDecimal if possible" do
+    @three.remainder(2).should == @one
+  end
+
+  describe "with Object" do
+    it "tries to coerce the other operand to self" do
+      object = mock("Object")
+      object.should_receive(:coerce).with(@three).and_return([@three, 2])
+      @three.remainder(object).should == @one
+    end
+  end
+
+  it "raises TypeError if the argument cannot be coerced to BigDecimal" do
+    -> {
+      @one.remainder('2')
+    }.should.raise(TypeError)
+  end
+
+end