```ruby
require_relative '../../spec_helper'

describe "Kernel#__dir__" do
  it "returns the real name of the directory containing the currently-executing file" do
    __dir__.should == File.realpath(File.dirname(__FILE__))
  end

  context "when used in eval with a given filename" do
    it "returns File.dirname(filename)" do
      eval("__dir__", nil, "foo.rb").should == "."
      eval("__dir__", nil, "foo/bar.rb").should == "foo"
    end
  end

  ruby_version_is ""..."2.7" do
    context "when used in eval with top level binding" do
      it "returns the real name of the directory containing the currently-executing file" do
        eval("__dir__", binding).should == File.realpath(File.dirname(__FILE__))
      end
    end
  end

  ruby_version_is "2.7" do
    context "when used in eval with top level binding" do
      it "returns nil" do
        eval("__dir__", binding).should == nil
      end
    end
  end
end
```

Fix version guard in __dir__ spec
user
```ruby
require_relative '../../spec_helper'

describe "Kernel#__dir__" do
  it "returns the real name of the directory containing the currently-executing file" do
    __dir__.should == File.realpath(File.dirname(__FILE__))
  end

  context "when used in eval with a given filename" do
    it "returns File.dirname(filename)" do
      eval("__dir__", nil, "foo.rb").should == "."
      eval("__dir__", nil, "foo/bar.rb").should == "foo"
    end
  end

  ruby_version_is ""..."2.8" do
    context "when used in eval with top level binding" do
      it "returns the real name of the directory containing the currently-executing file" do
        eval("__dir__", binding).should == File.realpath(File.dirname(__FILE__))
      end
    end
  end

  ruby_version_is "2.8" do
    context "when used in eval with top level binding" do
      it "returns nil" do
        eval("__dir__", binding).should == nil
      end
    end
  end
end
```
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