Added spec for Cli#add

Also fixed a bug in fakefs' File#open and use FakeFS.(de)activate! in before/after blocks to add rcov support.

spec/blocklist/cli_spec.rb

@@ -1,8 +1,16 @@
 require File.join(File.dirname(__FILE__), %w[.. spec_helper])
 require 'blocklist/cli'
-require 'fakefs'
+require 'fakefs/safe'
 
 describe Blocklist::Cli do
+  before(:each) do
+    FakeFS.activate!
+  end
+
+  after(:each) do
+    FakeFS.deactivate!
+  end
+
   def fake_hosts(content='')
     File.open('/etc/hosts','w') {|f| f.puts content}
   end
@@ -22,8 +30,22 @@ def fake_hosts(content='')
 # blocked
       STR
       cli = Blocklist::Cli.new(%w[list])
-      cli.should_receive(:puts).with("\nlocalhost\nblocked")
+      cli.should_receive(:puts).with("localhost\nblocked")
+      cli.run
+    end
+  end
+
+  describe 'add' do
+    it "should add a domain and its www-subdomain to a block's lines" do
+      fake_hosts <<-STR
+# localhost
+      STR
+      cli = Blocklist::Cli.new(%w[add localhost example.org])
       cli.run
+      File.read('/etc/hosts').should == <<-STR
+# localhost
+127.0.0.1       example.org www.example.org
+      STR
     end
   end
 end