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 ```1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 ``` ``````require File.expand_path('../../../spec_helper', __FILE__) describe "Integer#[]" do context "fixnum" do it "behaves like (n >> b) & 1" do 0b101[1].should == 0 0b101[2].should == 1 end it "returns 1 if the nth bit is set" do 15[1].should == 1 end it "returns 1 if the nth bit is set (in two's-complement representation)" do (-1)[1].should == 1 end it "returns 0 if the nth bit is not set" do 8[2].should == 0 end it "returns 0 if the nth bit is not set (in two's-complement representation)" do (-2)[0].should == 0 end it "returns 0 if the nth bit is greater than the most significant bit" do 2[3].should == 0 end it "returns 1 if self is negative and the nth bit is greater than the most significant bit" do (-1)[3].should == 1 end it "returns 0 when passed a negative argument" do 3[-1].should == 0 (-1)[-1].should == 0 end it "calls #to_int to convert the argument to an Integer and returns 1 if the nth bit is set" do obj = mock('1') obj.should_receive(:to_int).and_return(1) 2[obj].should == 1 end it "calls #to_int to convert the argument to an Integer and returns 0 if the nth bit is set" do obj = mock('0') obj.should_receive(:to_int).and_return(0) 2[obj].should == 0 end it "accepts a Float argument and returns 0 if the bit at the truncated value is not set" do 13[1.3].should == 0 end it "accepts a Float argument and returns 1 if the bit at the truncated value is set" do 13[2.1].should == 1 end it "raises a TypeError when passed a String" do lambda { 3["3"] }.should raise_error(TypeError) end it "raises a TypeError when #to_int does not return an Integer" do obj = mock('asdf') obj.should_receive(:to_int).and_return("asdf") lambda { 3[obj] }.should raise_error(TypeError) end it "calls #to_int to coerce a String to a Bignum and returns 0" do obj = mock('bignum value') obj.should_receive(:to_int).and_return(bignum_value) 3[obj].should == 0 end it "returns 0 when passed a Float in the range of a Bignum" do 3[bignum_value.to_f].should == 0 end end context "bignum" do before :each do @bignum = bignum_value(4996) end it "returns the nth bit in the binary representation of self" do @bignum[2].should == 1 @bignum[9.2].should == 1 @bignum[21].should == 0 @bignum[0xffffffff].should == 0 @bignum[-0xffffffff].should == 0 end it "tries to convert the given argument to an Integer using #to_int" do @bignum[1.3].should == @bignum[1] (obj = mock('2')).should_receive(:to_int).at_least(1).and_return(2) @bignum[obj].should == 1 end it "raises a TypeError when the given argument can't be converted to Integer" do obj = mock('asdf') lambda { @bignum[obj] }.should raise_error(TypeError) obj.should_receive(:to_int).and_return("asdf") lambda { @bignum[obj] }.should raise_error(TypeError) end end end ``````