diff --git a/lib/common/browser.rb b/lib/common/browser.rb
index 033dd5ce..63017212 100644
--- a/lib/common/browser.rb
+++ b/lib/common/browser.rb
@@ -24,20 +24,19 @@ class Browser
   attr_reader :hydra, :config_file, :cache_dir
 
   # @param [ Hash ] options
-  # @options
+  #
+  # @return [ Browser ]
   def initialize(options = {})
     @config_file = options[:config_file] || CONF_DIR + '/browser.conf.json'
     @cache_dir   = options[:cache_dir]   || CACHE_DIR + '/browser'
 
-    #options.delete(:config_file)
-
     load_config()
+    override_config(options)
 
-    #if options.length > 0
-      override_config(options)
-    #end
+    unless @hydra
+      @hydra = Typhoeus::Hydra.new(max_concurrency: self.max_threads)
+    end
 
-    @hydra = Typhoeus::Hydra.new(max_concurrency: self.max_threads)
     @cache = TyphoeusCache.new(@cache_dir)
     @cache.clean
 
@@ -46,6 +45,9 @@ class Browser
 
   private_class_method :new
 
+  # @param [ Hash ] options
+  #
+  # @return [ Browser ]
   def self.instance(options = {})
     unless @@instance
       @@instance = new(options)
@@ -57,8 +59,13 @@ class Browser
     @@instance = nil
   end
 
-  # TODO reload hydra (if the .load_config is called on a browser object,
-  # hydra will not have the new @max_threads)
+  #
+  # If an option was set but is not in the new config_file
+  # it's value is kept
+  #
+  # @param [ String ] config_file
+  #
+  # @return [ void ]
   def load_config(config_file = nil)
     @config_file = config_file || @config_file
 
@@ -77,10 +84,17 @@ class Browser
     end
   end
 
+  # @param [ String ] url
+  # @param [ Hash ] params
+  #
+  # @return [ Typhoeus::Request ]
   def forge_request(url, params = {})
     Typhoeus::Request.new(url, merge_request_params(params))
   end
 
+  # @param [ Hash ] params
+  #
+  # @return [ Hash ]
   def merge_request_params(params = {})
     params = Browser.append_params_header_field(
       params,
@@ -121,7 +135,11 @@ class Browser
 
   private
 
-  # return Array
+  # @param [ Hash ] params
+  # @param [ String ] field
+  # @param [ Mixed ] field_value
+  #
+  # @return [ Array ]
   def self.append_params_header_field(params = {}, field, field_value)
     if !params.has_key?(:headers)
       params = params.merge(:headers => { field => field_value })
diff --git a/lib/common/browser/options.rb b/lib/common/browser/options.rb
index 364ca346..3c5a47b2 100644
--- a/lib/common/browser/options.rb
+++ b/lib/common/browser/options.rb
@@ -5,9 +5,9 @@ class Browser
 
     USER_AGENT_MODES = %w{ static semi-static random }
 
-    attr_reader   :basic_auth, :user_agent_mode, :proxy, :proxy_auth
     attr_accessor :available_user_agents, :cache_ttl
-    attr_writer   :max_threads, :user_agent
+    attr_reader   :basic_auth, :user_agent_mode, :proxy, :proxy_auth
+    attr_writer   :user_agent
 
     # Sets the Basic Authentification credentials
     # Accepted format:
@@ -32,11 +32,22 @@ class Browser
       @max_threads || 1
     end
 
+    def max_threads=(threads)
+      if threads.is_a?(Integer) && threads > 0
+        @max_threads = threads
+        @hydra = Typhoeus::Hydra.new(max_concurrency: threads)
+      else
+        raise 'max_threads must be an Integer > 0'
+      end
+    end
+
     # Sets the user_agent_mode, which can be one of the following:
     #   static:      The UA is defined by the user, and will be the same in each requests
     #   semi-static: The UA is randomly chosen at the first request, and will not change
     #   random:      UA randomly chosen each request
     #
+    # UA are from @available_user_agents
+    #
     # @param [ String ] ua_mode
     #
     # @return [ void ]
diff --git a/spec/lib/common/browser_spec.rb b/spec/lib/common/browser_spec.rb
index 7fe078b5..da25aea2 100644
--- a/spec/lib/common/browser_spec.rb
+++ b/spec/lib/common/browser_spec.rb
@@ -19,11 +19,8 @@ describe Browser do
     ['user_agent', 'user_agent_mode', 'available_user_agents', 'proxy',
      'max_threads', 'cache_ttl']
   }
-
-  before :all do
-    @json_config_without_proxy = JSON.parse(File.read(CONFIG_FILE_WITHOUT_PROXY))
-    @json_config_with_proxy    = JSON.parse(File.read(CONFIG_FILE_WITH_PROXY))
-  end
+  let(:json_config_without_proxy) { JSON.parse(File.read(CONFIG_FILE_WITHOUT_PROXY)) }
+  let(:json_config_with_proxy)    { JSON.parse(File.read(CONFIG_FILE_WITH_PROXY)) }
 
   def check_instance_variables(browser, json_expected_vars)
     json_expected_vars['max_threads'] ||= 1 # max_thread can not be nil
@@ -44,7 +41,7 @@ describe Browser do
 
     context "when default config_file = #{CONFIG_FILE_WITHOUT_PROXY}" do
       it 'will check the instance vars' do
-        @json_expected_vars = @json_config_without_proxy
+        @json_expected_vars = json_config_without_proxy
       end
     end
 
@@ -52,7 +49,7 @@ describe Browser do
       let(:options) { { config_file: CONFIG_FILE_WITH_PROXY } }
 
       it 'will check the instance vars' do
-        @json_expected_vars = @json_config_with_proxy
+        @json_expected_vars = json_config_with_proxy
       end
     end
 
@@ -63,19 +60,32 @@ describe Browser do
       after { subject.cache_dir.should == cache_dir }
 
       it 'sets @cache_dir' do
-        @json_expected_vars = @json_config_without_proxy
+        @json_expected_vars = json_config_without_proxy
       end
     end
   end
 
-  # TODO
   describe '#load_config' do
-    it 'should raise an error if file is a symlink' do
-      symlink = './rspec_symlink'
+    context 'when config_file is a symlink' do
+      let(:config_file) { './rspec_symlink' }
 
-      File.symlink('./testfile', symlink)
-      expect { browser.load_config(symlink) }.to raise_error("[ERROR] Config file is a symlink.")
-      File.unlink(symlink)
+      it 'raises an error' do
+        File.symlink('./testfile', config_file)
+        expect { browser.load_config(config_file) }.to raise_error("[ERROR] Config file is a symlink.")
+        File.unlink(config_file)
+      end
+    end
+
+    context 'otherwise' do
+      after do
+        browser.load_config(@config_file)
+        check_instance_variables(browser, @expected)
+      end
+
+      it 'sets the correct variables' do
+        @config_file = CONFIG_FILE_WITH_PROXY
+        @expected    = json_config_without_proxy.merge(json_config_with_proxy)
+      end
     end
   end
 
@@ -197,8 +207,7 @@ describe Browser do
 
       url = 'http://example.localhost'
 
-      stub_request(:get, url).
-        to_return(status: 200, body: 'Hello World !')
+      stub_request(:get, url).to_return(status: 200, body: 'Hello World !')
 
       response1 = Browser.get(url)
       response2 = Browser.get(url)
@@ -212,8 +221,9 @@ describe Browser do
     it 'should not throw an encoding exception' do
       url = SPEC_FIXTURES_DIR + '/utf8.html'
       stub_request(:get, url).to_return(status: 200, body: File.read(url))
-      response1 = Browser.get(url)
-      expect { response1.body }.to_not raise_error
+
+      response = Browser.get(url)
+      expect { response.body }.to_not raise_error
     end
   end
 end
diff --git a/spec/shared_examples/browser/options.rb b/spec/shared_examples/browser/options.rb
index 01011c35..97d34998 100644
--- a/spec/shared_examples/browser/options.rb
+++ b/spec/shared_examples/browser/options.rb
@@ -7,10 +7,10 @@ shared_examples 'Browser::Options' do
 
     after do
       if @expected
-        subject.basic_auth = @auth
-        subject.basic_auth.should == @expected
+        browser.basic_auth = @auth
+        browser.basic_auth.should == @expected
       else
-        expect { subject.basic_auth = @auth }.to raise_error(exception)
+        expect { browser.basic_auth = @auth }.to raise_error(exception)
       end
     end
 
@@ -41,18 +41,29 @@ shared_examples 'Browser::Options' do
     end
   end
 
-  describe '#max_threads' do
+  describe '#max_threads= & #max_threads' do
+    let(:exception) { 'max_threads must be an Integer > 0' }
+
     after do
-      subject.max_threads = @max_threads
-      subject.max_threads.should == @expected
+      if @expected
+        browser.max_threads = @max_threads
+        browser.max_threads.should == @expected
+      else
+        expect { browser.max_threads = @max_threads }.to raise_error(exception)
+      end
     end
 
-    context 'when no @max_threads' do
-      @max_threads = nil
-      @expected    = 1
+    context 'when the argument is not an Integer > 0' do
+      it 'raises an error' do
+        @max_thrads = nil
+      end
+
+      it 'raises an error' do
+        @max_threads = -3
+      end
     end
 
-    context 'when @max_threads' do
+    context 'when the argument is an Integer' do
       it 'returns the @max_threads' do
         @max_threads = 10
         @expected    = 10
@@ -64,18 +75,18 @@ shared_examples 'Browser::Options' do
     # Testing all valid modes
     Browser::USER_AGENT_MODES.each do |user_agent_mode|
       it "sets & returns #{user_agent_mode}" do
-        subject.user_agent_mode = user_agent_mode
-        subject.user_agent_mode.should === user_agent_mode
+        browser.user_agent_mode = user_agent_mode
+        browser.user_agent_mode.should === user_agent_mode
       end
     end
 
     it 'sets the mode to "static" if nil is given' do
-      subject.user_agent_mode = nil
-      subject.user_agent_mode.should === 'static'
+      browser.user_agent_mode = nil
+      browser.user_agent_mode.should === 'static'
     end
 
     it 'raises an error if the mode is not valid' do
-      expect { subject.user_agent_mode = 'invalid-mode' }.to raise_error
+      expect { browser.user_agent_mode = 'invalid-mode' }.to raise_error
     end
   end
 
@@ -84,39 +95,39 @@ shared_examples 'Browser::Options' do
 
     context 'when static mode' do
       it 'returns the same user agent' do
-        subject.user_agent = 'fake UA'
-        subject.user_agent_mode = 'static'
+        browser.user_agent      = 'fake UA'
+        browser.user_agent_mode = 'static'
 
         (1..3).each do
-          subject.user_agent.should === 'fake UA'
+          browser.user_agent.should === 'fake UA'
         end
       end
     end
 
     context 'when semi-static mode' do
       it 'chooses a random user_agent in the available_user_agents array and always return it' do
-        subject.available_user_agents = available_user_agents
-        subject.user_agent            = 'Firefox 11.0'
-        subject.user_agent_mode       = 'semi-static'
+        browser.available_user_agents = available_user_agents
+        browser.user_agent            = 'Firefox 11.0'
+        browser.user_agent_mode       = 'semi-static'
 
-        user_agent = subject.user_agent
+        user_agent = browser.user_agent
         user_agent.should_not === 'Firefox 11.0'
         available_user_agents.include?(user_agent).should be_true
 
         (1..3).each do
-          subject.user_agent.should === user_agent
+          browser.user_agent.should === user_agent
         end
       end
     end
 
     context 'when random' do
       it 'returns a random user agent each time' do
-        subject.available_user_agents = available_user_agents
-        subject.user_agent_mode       = 'random'
+        browser.available_user_agents = available_user_agents
+        browser.user_agent_mode       = 'random'
 
-        ua_1 = subject.user_agent
-        ua_2 = subject.user_agent
-        ua_3 = subject.user_agent
+        ua_1 = browser.user_agent
+        ua_2 = browser.user_agent
+        ua_3 = browser.user_agent
 
         fail if ua_1 === ua_2 and ua_2 === ua_3
       end
@@ -128,10 +139,10 @@ shared_examples 'Browser::Options' do
 
     after do
       if @expected
-        subject.proxy = @proxy
-        subject.proxy.should == @expected
+        browser.proxy = @proxy
+        browser.proxy.should == @expected
       else
-        expect { subject.proxy = @proxy }.to raise_error(exception)
+        expect { browser.proxy = @proxy }.to raise_error(exception)
       end
     end
 
@@ -152,10 +163,10 @@ shared_examples 'Browser::Options' do
 
     after :each do
       if @expected
-        subject.proxy_auth = @proxy_auth
-        subject.proxy_auth.should === @expected
+        browser.proxy_auth = @proxy_auth
+        browser.proxy_auth.should === @expected
       else
-        expect { subject.proxy_auth = @proxy_auth }.to raise_error
+        expect { browser.proxy_auth = @proxy_auth }.to raise_error
       end
     end
 
@@ -206,16 +217,16 @@ shared_examples 'Browser::Options' do
 
   describe '#override_config' do
     after do
-      subject.send(:override_config, override_options)
+      browser.send(:override_config, override_options)
     end
 
-    let(:config) { JSON.parse(File.read(subject.config_file)) }
+    let(:config) { JSON.parse(File.read(browser.config_file)) }
 
     context 'when an option value is nil' do
       let(:override_options) { { max_threads: nil } }
 
       it 'does not set it' do
-        subject.should_not_receive(:max_threads=)
+        browser.should_not_receive(:max_threads=)
       end
     end
 
@@ -223,7 +234,7 @@ shared_examples 'Browser::Options' do
       let(:override_options) { { not_allowed: 'owned' } }
 
       it 'does not set it' do
-        subject.should_not_receive(:not_allowed=)
+        browser.should_not_receive(:not_allowed=)
       end
     end
 
@@ -231,7 +242,7 @@ shared_examples 'Browser::Options' do
       let(:override_options) { { max_threads: 30 } }
 
       it 'sets it' do
-        subject.should_receive(:max_threads=).with(30)
+        browser.should_receive(:max_threads=).with(30)
       end
     end
 
@@ -241,9 +252,9 @@ shared_examples 'Browser::Options' do
       }
 
       it 'sets @max_threads, @proxy' do
-        subject.should_not_receive(:not_allowed=)
-        subject.should_receive(:max_threads=).with(10)
-        subject.should_receive(:proxy=).with('host:port')
+        browser.should_not_receive(:not_allowed=)
+        browser.should_receive(:max_threads=).with(10)
+        browser.should_receive(:proxy=).with('host:port')
       end
     end
   end