```ruby
require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)

describe "Kernel#binding" do
  it "is a private method" do
    Kernel.should have_private_instance_method(:binding)
  end
  
  before(:each) do
    @b1 = KernelSpecs::Binding.new(99).get_binding
  end

  it "returns a Binding object" do
    @b1.kind_of?(Binding).should == true
  end

  it "encapsulates the execution context properly" do
    eval("@secret", @b1).should == 100
    eval("a", @b1).should == true
    eval("b", @b1).should == true
    eval("@@super_secret", @b1).should == "password"

    eval("square(2)", @b1).should == 4
    eval("self.square(2)", @b1).should == 4

    eval("a = false", @b1)
    eval("a", @b1).should == false
  end

  it "raises a NameError on undefined variable" do
    lambda { eval("a_fake_variable", @b1) }.should raise_error(NameError)
  end
end

describe "Kernel.binding" do
  it "needs to be reviewed for spec completeness"
end
```

Add spec for 'self' in Kernel.binding, which differs between 1.8 and 1.9.
user
```ruby
require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)

describe "Kernel#binding" do
  it "is a private method" do
    Kernel.should have_private_instance_method(:binding)
  end
  
  before(:each) do
    @b1 = KernelSpecs::Binding.new(99).get_binding
  end

  it "returns a Binding object" do
    @b1.kind_of?(Binding).should == true
  end

  it "encapsulates the execution context properly" do
    eval("@secret", @b1).should == 100
    eval("a", @b1).should == true
    eval("b", @b1).should == true
    eval("@@super_secret", @b1).should == "password"

    eval("square(2)", @b1).should == 4
    eval("self.square(2)", @b1).should == 4

    eval("a = false", @b1)
    eval("a", @b1).should == false
  end

  it "raises a NameError on undefined variable" do
    lambda { eval("a_fake_variable", @b1) }.should raise_error(NameError)
  end
end

describe "Kernel.binding" do
  it "needs to be reviewed for spec completeness"
  
  ruby_version_is ""..."1.9" do
    it "uses Kernel for 'self' in the binding" do
      eval('self', Kernel.binding).should == Kernel
    end
  end
  
  ruby_version_is "1.9" do
    it "uses the caller's self for 'self' in the binding" do
      eval('self', Kernel.binding).should == self
    end
  end
end
```
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