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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, 33).should eql(-8589934592)
(-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)
(-2).send(@method, 65).should eql(-36893488147419103232)
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
}.should complain(/warning: in a\*\*b, b may be too big/)
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 == 115792089237316196603666111261383895964500887398800252671052694326794607293761
(@bignum.send(@method, 1.3)).should be_close(11109528802438156839288832.0, TOLERANCE)
end
it "raises a TypeError when given a non-Integer" do
-> { @bignum.send(@method, mock('10')) }.should raise_error(TypeError)
-> { @bignum.send(@method, "10") }.should raise_error(TypeError)
-> { @bignum.send(@method, :symbol) }.should raise_error(TypeError)
end
it "switch to a Float when the values is too big" do
flt = nil
-> {
flt = @bignum.send(@method, @bignum)
}.should complain(/warning: in a\*\*b, b may be too big/)
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_value).send(@method, (1.0/2)).should be_close(Complex(0.0, 4294967296.0), TOLERANCE)
(-@bignum).send(@method, (1.0/3)) .should be_close(Complex(1321122.9748145656, 2288252.1154253655), TOLERANCE)
(-@bignum).send(@method, Rational(1,3)).should be_close(Complex(1321122.9748145656, 2288252.1154253655), TOLERANCE)
end
end
end
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