```ruby
require 'spec_helper'

describe Adhearsion do
  subject { Adhearsion }

  describe "while accessing the config method" do
    it "should return a Configuration instance" do
      subject.config.should be_instance_of Adhearsion::Configuration
    end

    it "should execute a block" do
      foo = Object.new
      flexmock(foo).should_receive(:bar).once
      Adhearsion.config do |config|
        foo.bar
      end
    end
  end

  describe "#router" do
    its(:router) { should be_a Adhearsion::Router }

    it "should always use the same router" do
      Adhearsion.router.should be Adhearsion.router
    end

    it "should pass a block along to the router" do
      foo = nil
      Adhearsion.router do
        foo = self
      end

      foo.should be Adhearsion.router
    end
  end

  describe "while accessing the ahn_root= method" do
    it "should update properly the config root variable" do
      Adhearsion.ahn_root = "./"
      Adhearsion.config[:platform].root.should == Dir.getwd
    end

    it "should update properly the config root variable when path is nil" do
      Adhearsion.ahn_root = nil
      Adhearsion.config[:platform].root.should be_nil
    end
  end
end
```

Remove a redundant explicit subject
user
```ruby
require 'spec_helper'

describe Adhearsion do
  describe "while accessing the config method" do
    it "should return a Configuration instance" do
      subject.config.should be_instance_of Adhearsion::Configuration
    end

    it "should execute a block" do
      foo = Object.new
      flexmock(foo).should_receive(:bar).once
      Adhearsion.config do |config|
        foo.bar
      end
    end
  end

  describe "#router" do
    its(:router) { should be_a Adhearsion::Router }

    it "should always use the same router" do
      Adhearsion.router.should be Adhearsion.router
    end

    it "should pass a block along to the router" do
      foo = nil
      Adhearsion.router do
        foo = self
      end

      foo.should be Adhearsion.router
    end
  end

  describe "while accessing the ahn_root= method" do
    it "should update properly the config root variable" do
      Adhearsion.ahn_root = "./"
      Adhearsion.config[:platform].root.should == Dir.getwd
    end

    it "should update properly the config root variable when path is nil" do
      Adhearsion.ahn_root = nil
      Adhearsion.config[:platform].root.should be_nil
    end
  end
end
```
assistant