1 files changed, 111 insertions, 0 deletions
diff --git a/spec/ruby/core/integer/element_reference_spec.rb b/spec/ruby/core/integer/element_reference_spec.rb
new file mode 100644
index 0000000000..2a2e8981a3
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+++ b/spec/ruby/core/integer/element_reference_spec.rb
@@ -0,0 +1,111 @@
+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