Update to ruby/spec@83063a3

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62094 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/core/integer/shared/exponent.rb

@@ -0,0 +1,118 @@
+describe :integer_exponent, shared: true do
+  context "fixnum" do
+    it "returns self raised to the given power" do
+      2.send(@method, 0).should eql 1
+      2.send(@method, 1).should eql 2
+      2.send(@method, 2).should eql 4
+
+      9.send(@method, 0.5).should eql 3.0
+      9.send(@method, Rational(1, 2)).should eql 3.0
+      5.send(@method, -1).to_f.to_s.should == '0.2'
+
+      2.send(@method, 40).should eql 1099511627776
+    end
+
+    it "overflows the answer to a bignum transparently" do
+      2.send(@method, 29).should eql 536870912
+      2.send(@method, 30).should eql 1073741824
+      2.send(@method, 31).should eql 2147483648
+      2.send(@method, 32).should eql 4294967296
+
+      2.send(@method, 61).should eql 2305843009213693952
+      2.send(@method, 62).should eql 4611686018427387904
+      2.send(@method, 63).should eql 9223372036854775808
+      2.send(@method, 64).should eql 18446744073709551616
+      8.send(@method, 23).should eql 590295810358705651712
+    end
+
+    it "raises negative numbers to the given power" do
+      (-2).send(@method, 29).should eql(-536870912)
+      (-2).send(@method, 30).should eql(1073741824)
+      (-2).send(@method, 31).should eql(-2147483648)
+      (-2).send(@method, 32).should eql(4294967296)
+
+      (-2).send(@method, 61).should eql(-2305843009213693952)
+      (-2).send(@method, 62).should eql(4611686018427387904)
+      (-2).send(@method, 63).should eql(-9223372036854775808)
+      (-2).send(@method, 64).should eql(18446744073709551616)
+    end
+
+    it "can raise 1 to a bignum safely" do
+      1.send(@method, 4611686018427387904).should eql 1
+    end
+
+    it "can raise -1 to a bignum safely" do
+      (-1).send(@method, 4611686018427387904).should eql(1)
+      (-1).send(@method, 4611686018427387905).should eql(-1)
+    end
+
+    it "returns Float::INFINITY when the number is too big" do
+      2.send(@method, 427387904).should == Float::INFINITY
+    end
+
+    it "raises a ZeroDivisionError for 0 ** -1" do
+      -> { 0.send(@method, -1) }.should raise_error(ZeroDivisionError)
+      -> { 0.send(@method, Rational(-1, 1)) }.should raise_error(ZeroDivisionError)
+    end
+
+    it "returns Float::INFINITY for 0 ** -1.0" do
+      0.send(@method, -1.0).should == Float::INFINITY
+    end
+
+    it "raises a TypeError when given a non-numeric power" do
+      -> { 13.send(@method, "10") }.should raise_error(TypeError)
+      -> { 13.send(@method, :symbol) }.should raise_error(TypeError)
+      -> { 13.send(@method, nil) }.should raise_error(TypeError)
+    end
+
+    it "coerces power and calls #**" do
+      num_2 = mock("2")
+      num_13 = mock("13")
+      num_2.should_receive(:coerce).with(13).and_return([num_13, num_2])
+      num_13.should_receive(:**).with(num_2).and_return(169)
+
+      13.send(@method, num_2).should == 169
+    end
+
+    it "returns Float when power is Float" do
+      2.send(@method, 2.0).should == 4.0
+    end
+
+    it "returns Rational when power is Rational" do
+      2.send(@method, Rational(2, 1)).should == Rational(4, 1)
+    end
+
+    it "returns a complex number when negative and raised to a fractional power" do
+      (-8).send(@method, 1.0/3)         .should be_close(Complex(1, 1.73205), TOLERANCE)
+      (-8).send(@method, Rational(1, 3)).should be_close(Complex(1, 1.73205), TOLERANCE)
+    end
+  end
+
+  context "bignum" do
+    before :each do
+      @bignum = bignum_value(47)
+    end
+
+    it "returns self raised to other power" do
+      (@bignum.send(@method, 4)).should == 7237005577332262361485077344629993318496048279512298547155833600056910050625
+      (@bignum.send(@method, 1.2)).should be_close(57262152889751597425762.57804, TOLERANCE)
+    end
+
+    it "raises a TypeError when given a non-Integer" do
+      lambda { @bignum.send(@method, mock('10')) }.should raise_error(TypeError)
+      lambda { @bignum.send(@method, "10") }.should raise_error(TypeError)
+      lambda { @bignum.send(@method, :symbol) }.should raise_error(TypeError)
+    end
+
+    it "switch to a Float when the values is too big" do
+      flt = @bignum.send(@method, @bignum)
+      flt.should be_kind_of(Float)
+      flt.infinite?.should == 1
+    end
+
+    it "returns a complex number when negative and raised to a fractional power" do
+      ((-@bignum).send(@method, (1.0/3)))      .should be_close(Complex(1048576,1816186.907597341), TOLERANCE)
+      ((-@bignum).send(@method, Rational(1,3))).should be_close(Complex(1048576,1816186.907597341), TOLERANCE)
+    end
+  end
+end