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Diffstat (limited to 'spec/ruby/core/integer/left_shift_spec.rb')
| -rw-r--r-- | spec/ruby/core/integer/left_shift_spec.rb | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/spec/ruby/core/integer/left_shift_spec.rb b/spec/ruby/core/integer/left_shift_spec.rb new file mode 100644 index 0000000000..86c2b18ae2 --- /dev/null +++ b/spec/ruby/core/integer/left_shift_spec.rb @@ -0,0 +1,211 @@ +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 a Bignum == fixnum_max * 2 when fixnum_max << 1 and n > 0" do + result = fixnum_max << 1 + result.should be_an_instance_of(Integer) + result.should == fixnum_max * 2 + end + + it "returns a Bignum == fixnum_min * 2 when fixnum_min << 1 and n < 0" do + result = fixnum_min << 1 + result.should be_an_instance_of(Integer) + 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 + + obj = mock("to_int_neg_bignum") + obj.should_receive(:to_int).and_return(-bignum_value) + (3 << obj).should == 0 + 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") + + -> { 3 << obj }.should raise_error(TypeError) + end + + it "raises a TypeError when passed nil" do + -> { 3 << nil }.should raise_error(TypeError) + end + + it "raises a TypeError when passed a String" do + -> { 3 << "4" }.should raise_error(TypeError) + end + end + + context "bignum" do + before :each do + @bignum = bignum_value * 8 # 2 ** 67 + 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 a Fixnum == fixnum_max when (fixnum_max * 2) << -1 and n > 0" do + result = (fixnum_max * 2) << -1 + result.should be_an_instance_of(Integer) + 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(Integer) + 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") + + -> { @bignum << obj }.should raise_error(TypeError) + end + + it "raises a TypeError when passed nil" do + -> { @bignum << nil }.should raise_error(TypeError) + end + + it "raises a TypeError when passed a String" do + -> { @bignum << "4" }.should raise_error(TypeError) + end + end + + context "when m is a bignum or larger than int" do + it "returns -1 when m < 0 and n < 0" do + (-1 << -bignum_value).should == -1 + (-1 << -(2**40)).should == -1 + + (-bignum_value << -bignum_value).should == -1 + (-bignum_value << -(2**40)).should == -1 + end + + it "returns 0 when m < 0 and n >= 0" do + (0 << -bignum_value).should == 0 + (1 << -bignum_value).should == 0 + (bignum_value << -bignum_value).should == 0 + + (0 << -(2**40)).should == 0 + (1 << -(2**40)).should == 0 + (bignum_value << -(2**40)).should == 0 + end + + it "returns 0 when m > 0 long and n == 0" do + (0 << (2**40)).should == 0 + end + + it "returns 0 when m > 0 bignum and n == 0" do + (0 << bignum_value).should == 0 + end + + it "raises RangeError when m > 0 and n != 0" do + # https://bugs.ruby-lang.org/issues/18518#note-9 + limit = RUBY_ENGINE == 'ruby' ? 2**67 : 2**32 + + coerce_long = mock("long") + coerce_long.stub!(:to_int).and_return(limit) + coerce_bignum = mock("bignum") + coerce_bignum.stub!(:to_int).and_return(bignum_value) + exps = [limit, coerce_long] + exps << bignum_value << coerce_bignum if bignum_value >= limit + + exps.each { |exp| + -> { (1 << exp) }.should raise_error(RangeError, 'shift width too big') + -> { (-1 << exp) }.should raise_error(RangeError, 'shift width too big') + -> { (bignum_value << exp) }.should raise_error(RangeError, 'shift width too big') + -> { (-bignum_value << exp) }.should raise_error(RangeError, 'shift width too big') + } + end + end +end |