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require_relative '../../spec_helper'
describe "Integer#<< (with n << m)" do
context "fixnum" do
it "returns n shifted left m bits when n > 0, m > 0" do
(1 << 1).should == 2
end
it "returns n shifted left m bits when n < 0, m > 0" do
(-1 << 1).should == -2
(-7 << 1).should == -14
(-42 << 2).should == -168
end
it "returns n shifted right m bits when n > 0, m < 0" do
(2 << -1).should == 1
end
it "returns n shifted right m bits when n < 0, m < 0" do
(-2 << -1).should == -1
end
it "returns 0 when n == 0" do
(0 << 1).should == 0
end
it "returns n when n > 0, m == 0" do
(1 << 0).should == 1
end
it "returns n when n < 0, m == 0" do
(-1 << 0).should == -1
end
it "returns 0 when n > 0, m < 0 and n < 2**-m" do
(3 << -2).should == 0
(7 << -3).should == 0
(127 << -7).should == 0
# To make sure the exponent is not truncated
(7 << -32).should == 0
(7 << -64).should == 0
end
it "returns -1 when n < 0, m < 0 and n > -(2**-m)" do
(-3 << -2).should == -1
(-7 << -3).should == -1
(-127 << -7).should == -1
# To make sure the exponent is not truncated
(-7 << -32).should == -1
(-7 << -64).should == -1
end
it "returns 0 when m < 0 and m is a Bignum" do
(3 << -bignum_value).should == 0
end
it "returns an Bignum == fixnum_max * 2 when fixnum_max << 1 and n > 0" do
result = fixnum_max << 1
result.should be_an_instance_of(Bignum)
result.should == fixnum_max * 2
end
it "returns an Bignum == fixnum_min * 2 when fixnum_min << 1 and n < 0" do
result = fixnum_min << 1
result.should be_an_instance_of(Bignum)
result.should == fixnum_min * 2
end
it "calls #to_int to convert the argument to an Integer" do
obj = mock("4")
obj.should_receive(:to_int).and_return(4)
(3 << obj).should == 48
end
it "raises a TypeError when #to_int does not return an Integer" do
obj = mock("a string")
obj.should_receive(:to_int).and_return("asdf")
lambda { 3 << obj }.should raise_error(TypeError)
end
it "raises a TypeError when passed nil" do
lambda { 3 << nil }.should raise_error(TypeError)
end
it "raises a TypeError when passed a String" do
lambda { 3 << "4" }.should raise_error(TypeError)
end
end
context "bignum" do
before :each do
@bignum = bignum_value * 16
end
it "returns n shifted left m bits when n > 0, m > 0" do
(@bignum << 4).should == 2361183241434822606848
end
it "returns n shifted left m bits when n < 0, m > 0" do
(-@bignum << 9).should == -75557863725914323419136
end
it "returns n shifted right m bits when n > 0, m < 0" do
(@bignum << -1).should == 73786976294838206464
end
it "returns n shifted right m bits when n < 0, m < 0" do
(-@bignum << -2).should == -36893488147419103232
end
it "returns n when n > 0, m == 0" do
(@bignum << 0).should == @bignum
end
it "returns n when n < 0, m == 0" do
(-@bignum << 0).should == -@bignum
end
it "returns 0 when m < 0 and m == p where 2**p > n >= 2**(p-1)" do
(@bignum << -68).should == 0
end
it "returns 0 when m < 0 and m is a Bignum" do
(@bignum << -bignum_value).should == 0
end
it "returns a Fixnum == fixnum_max when (fixnum_max * 2) << -1 and n > 0" do
result = (fixnum_max * 2) << -1
result.should be_an_instance_of(Fixnum)
result.should == fixnum_max
end
it "returns a Fixnum == fixnum_min when (fixnum_min * 2) << -1 and n < 0" do
result = (fixnum_min * 2) << -1
result.should be_an_instance_of(Fixnum)
result.should == fixnum_min
end
it "calls #to_int to convert the argument to an Integer" do
obj = mock("4")
obj.should_receive(:to_int).and_return(4)
(@bignum << obj).should == 2361183241434822606848
end
it "raises a TypeError when #to_int does not return an Integer" do
obj = mock("a string")
obj.should_receive(:to_int).and_return("asdf")
lambda { @bignum << obj }.should raise_error(TypeError)
end
it "raises a TypeError when passed nil" do
lambda { @bignum << nil }.should raise_error(TypeError)
end
it "raises a TypeError when passed a String" do
lambda { @bignum << "4" }.should raise_error(TypeError)
end
end
end
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