diff --git a/.hound.yml b/.hound.yml
new file mode 100644
index 0000000..b7945ab
--- /dev/null
+++ b/.hound.yml
@@ -0,0 +1,3 @@
+ruby:
+  enabled: true
+  config_file: .rubocop.yml
diff --git a/.rubocop.yml b/.rubocop.yml
new file mode 100644
index 0000000..d16f9ce
--- /dev/null
+++ b/.rubocop.yml
@@ -0,0 +1,5 @@
+Style/StringLiterals:
+  EnforcedStyle: single_quotes
+
+Style/DotPosition:
+  EnforcedStyle: trailing
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..2bf67af
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,46 @@
+## Contributing
+In the spirit of [free software][free-sw], **everyone** is encouraged to help
+improve this project.
+
+[free-sw]: http://www.fsf.org/licensing/essays/free-sw.html
+
+Here are some ways *you* can contribute:
+
+* by using alpha, beta, and prerelease versions
+* by reporting bugs
+* by suggesting new features
+* by writing or editing documentation
+* by writing specifications
+* by writing code (**no patch is too small**: fix typos, add comments, clean up
+  inconsistent whitespace)
+* by refactoring code
+* by fixing [issues][]
+* by reviewing patches
+
+[issues]: https://github.com/trema/switch_monitor/issues
+
+## Submitting an Issue
+We use the [GitHub issue tracker][issues] to track bugs and features. Before
+submitting a bug report or feature request, check to make sure it hasn't
+already been submitted. When submitting a bug report, please include a [Gist][]
+that includes a stack trace and any details that may be necessary to reproduce
+the bug, including your gem version, Ruby version, and operating system.
+Ideally, a bug report should include a pull request with failing specs.
+
+[gist]: https://gist.github.com/
+
+## Submitting a Pull Request
+1. [Fork the repository.][fork]
+2. [Create a topic branch.][branch]
+3. Add specs for your unimplemented feature or bug fix.
+4. Run `bundle exec rake spec`. If your specs pass, return to step 3.
+5. Implement your feature or bug fix.
+6. Run `bundle exec rake default`. If your specs fail, return to step 5.
+7. Run `open coverage/index.html`. If your changes are not completely covered
+   by your tests, return to step 3.
+8. Add, commit, and push your changes.
+9. [Submit a pull request.][pr]
+
+[fork]: http://help.github.com/fork-a-repo/
+[branch]: http://learn.github.com/p/branching.html
+[pr]: http://help.github.com/send-pull-requests/
diff --git a/Gemfile b/Gemfile
index 009a363..59b2ead 100644
--- a/Gemfile
+++ b/Gemfile
@@ -18,7 +18,7 @@ group :development, :test do
   gem 'rubocop', require: false
 end
 
-group :development do
+group :doc do
   gem 'inch', require: false
   gem 'yard', require: false
 end
diff --git a/Gemfile.lock b/Gemfile.lock
index ae9ae7e..1bdae40 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,22 +1,22 @@
 GIT
   remote: git://github.com/trema/phut.git
-  revision: 56b76d053a5f642cd0450e327e95cfcc126d73e2
+  revision: e28ea0b14036853ae61a73e2a3d48d56400a0a9d
   branch: develop
   specs:
     phut (0.1.0)
       gli (~> 2.12.2)
-      pio (~> 0.14.0)
+      pio (~> 0.15.0)
       pry (~> 0.10.1)
 
 GIT
   remote: git://github.com/trema/trema_ruby.git
-  revision: ae84f2f9827172ad782e26e60853a363363a1eba
+  revision: 41354a44af537668e5f806031ffe21b2393a154f
   branch: develop
   specs:
     trema (0.1.0)
-      bundler (~> 1.7.12)
+      bundler (~> 1.8.0)
       gli (~> 2.12.0)
-      pio (~> 0.14.0)
+      pio (~> 0.15.0)
       rake
 
 GEM
@@ -51,12 +51,12 @@ GEM
       simplecov (~> 0.9.1)
       term-ansicolor (~> 1.3)
       thor (~> 0.19.1)
-    cucumber (1.3.18)
+    cucumber (1.3.19)
       builder (>= 2.1.2)
       diff-lcs (>= 1.1.3)
       gherkin (~> 2.12)
       multi_json (>= 1.7.5, < 2.0)
-      multi_test (>= 0.1.1)
+      multi_test (>= 0.1.2)
     diff-lcs (1.2.5)
     docile (1.1.5)
     equalizer (0.0.9)
@@ -70,7 +70,7 @@ GEM
     given_core (3.6.0)
       sorcerer (>= 0.3.7)
     gli (2.12.2)
-    guard (2.12.0)
+    guard (2.12.1)
       formatador (>= 0.2.4)
       listen (~> 2.7)
       lumberjack (~> 1.0)
@@ -108,15 +108,15 @@ GEM
     method_source (0.8.2)
     mime-types (2.4.3)
     multi_json (1.10.1)
-    multi_test (0.1.1)
+    multi_test (0.1.2)
     nenv (0.2.0)
     netrc (0.10.2)
-    notiffany (0.0.4)
+    notiffany (0.0.5)
       nenv (~> 0.1)
       shellany (~> 0.0)
-    parser (2.2.0.2)
+    parser (2.2.0.3)
       ast (>= 1.1, < 3.0)
-    pio (0.14.0)
+    pio (0.15.0)
       bindata (~> 2.1.0)
     powerpack (0.1.0)
     procto (0.0.2)
@@ -129,9 +129,9 @@ GEM
     rb-fsevent (0.9.4)
     rb-inotify (0.9.5)
       ffi (>= 0.5.0)
-    reek (1.6.5)
-      parser (~> 2.2.0.pre.7)
-      rainbow (>= 1.99, < 3.0)
+    reek (2.0.0)
+      parser (~> 2.2)
+      rainbow (~> 2.0)
       unparser (~> 0.2.2)
     rest-client (1.7.2)
       mime-types (>= 1.16, < 3.0)
@@ -152,7 +152,7 @@ GEM
       diff-lcs (>= 1.2.0, < 2.0)
       rspec-support (~> 3.2.0)
     rspec-support (3.2.1)
-    rubocop (0.29.0)
+    rubocop (0.29.1)
       astrolabe (~> 1.3)
       parser (>= 2.2.0.1, < 3.0)
       powerpack (~> 0.1)
diff --git a/features/support/hooks.rb b/features/support/hooks.rb
index 9fa2c58..79b1456 100644
--- a/features/support/hooks.rb
+++ b/features/support/hooks.rb
@@ -1,7 +1,9 @@
-Before do
+Before('@sudo') do
+  fail 'sudo authentication failed' unless system 'sudo -v'
   @aruba_timeout_seconds = 10
 end
 
-After do
+After('@sudo') do
   run 'trema killall'
+  sleep 10
 end
diff --git a/features/switch_monitor.feature b/features/switch_monitor.feature
index 6c209cb..5c8b5b6 100644
--- a/features/switch_monitor.feature
+++ b/features/switch_monitor.feature
@@ -1,28 +1,37 @@
 Feature: Switch Monitor example
   Background:
-    Given a file named ".trema/config" with:
-    """
-    LOG_DIR: .
-    PID_DIR: .
-    SOCKET_DIR: .
-    """
-
-  Scenario: Run
     Given a file named "trema.conf" with:
     """
     vswitch { datapath_id 0x1 }
     vswitch { datapath_id 0x2 }
     vswitch { datapath_id 0x3 }
     """
-    When I successfully run `trema run ../../lib/switch_monitor.rb -c trema.conf -d`
-    And I run `sleep 5`
+
+  @sudo
+  Scenario: Run
+    When I run `trema run ../../lib/switch_monitor.rb -c trema.conf -p . -l . -s .` interactively
+    Then I wait for stdout to contain "SwitchMonitor started"
+    And I wait for stdout to contain "0x1 is up"
+    And I wait for stdout to contain "0x2 is up"
+    And I wait for stdout to contain "0x3 is up"
+    When I run `trema kill 0x2`
+    And I wait for stdout to contain "0x2 is down (all = 0x1, 0x3)"
+    When I run `trema up 0x2`
+    And I wait for stdout to contain "0x2 is up (all = 0x1, 0x2, 0x3)"
+
+  @sudo
+  Scenario: Run as a daemon
+    When I successfully run `trema run ../../lib/switch_monitor.rb -c trema.conf -d -p . -l . -s .`
+    And I run `sleep 10`
     Then a file named "SwitchMonitor.log" should exist
-    And the file "SwitchMonitor.log" should contain "Switch 0x1 is UP"
-    And the file "SwitchMonitor.log" should contain "Switch 0x2 is UP"
-    And the file "SwitchMonitor.log" should contain "Switch 0x3 is UP"
+    And the file "SwitchMonitor.log" should contain "0x1 is up"
+    And the file "SwitchMonitor.log" should contain "0x2 is up"
+    And the file "SwitchMonitor.log" should contain "0x3 is up"
+    And the file "SwitchMonitor.log" should contain "all = 0x1, 0x2, 0x3"
     When I successfully run `trema kill 0x2`
-    Then the file "SwitchMonitor.log" should contain "Switch 0x2 is DOWN"
-    Then a file named "open_vswitch.0x2.pid" should not exist
+    Then the file "SwitchMonitor.log" should contain "0x2 is down (all = 0x1, 0x3)"
+    And a file named "open_vswitch.0x2.pid" should not exist
     When I successfully run `trema up 0x2`
     Then a file named "open_vswitch.0x2.pid" should exist
+    And the file "SwitchMonitor.log" should contain "0x2 is up (all = 0x1, 0x2, 0x3)"
     
diff --git a/lib/switch_monitor.rb b/lib/switch_monitor.rb
index a7c969d..bc8e9c9 100644
--- a/lib/switch_monitor.rb
+++ b/lib/switch_monitor.rb
@@ -1,22 +1,23 @@
 # Switch liveness monitor.
 class SwitchMonitor < Trema::Controller
-  timer_event :show_switches, interval: 10.sec
-
-  def start(_argv)
+  def start(_args)
     @switches = []
+    logger.info 'SwitchMonitor started.'
   end
 
   def switch_ready(datapath_id)
-    @switches << datapath_id.to_hex
-    logger.info "Switch #{ datapath_id.to_hex } is UP"
+    @switches << datapath_id
+    logger.info "#{datapath_id.to_hex} is up (all = #{switches_in_string})"
   end
 
   def switch_disconnected(datapath_id)
-    @switches -= [datapath_id.to_hex]
-    logger.info "Switch #{ datapath_id.to_hex } is DOWN"
+    @switches -= [datapath_id]
+    logger.info "#{datapath_id.to_hex} is down (all = #{switches_in_string})"
   end
 
-  def show_switches
-    logger.info 'All switches = ' + @switches.sort.join(', ')
+  private
+
+  def switches_in_string
+    @switches.sort.map(&:to_hex).join(', ')
   end
 end
diff --git a/spec/lib/switch_monitor_spec.rb b/spec/lib/switch_monitor_spec.rb
index 698c5fe..44b00f8 100644
--- a/spec/lib/switch_monitor_spec.rb
+++ b/spec/lib/switch_monitor_spec.rb
@@ -2,4 +2,57 @@
 require 'switch_monitor'
 
 describe SwitchMonitor do
+  Given(:logger) { spy('logger') }
+  Given(:switch_monitor) do
+    SwitchMonitor.new.tap do |controller|
+      allow(controller).to receive(:logger).and_return(logger)
+    end
+  end
+
+  describe '#start' do
+    When { switch_monitor.start(args) }
+
+    context 'with []' do
+      Given(:args) { [] }
+      Then do
+        expect(logger).to(have_received(:info).with('SwitchMonitor started.'))
+      end
+
+      describe '#switch_ready' do
+        When { switch_monitor.switch_ready(dpid1) }
+
+        context 'with 0xabc' do
+          Given(:dpid1) { 0xabc }
+          Then do
+            expect(logger).to(have_received(:info).
+                              with('0xabc is up (all = 0xabc)'))
+          end
+
+          describe '#switch_ready' do
+            When { switch_monitor.switch_ready(dpid2) }
+
+            context 'with 0xdef' do
+              Given(:dpid2) { 0xdef }
+              Then do
+                expect(logger).to(have_received(:info).
+                                  with('0xdef is up (all = 0xabc, 0xdef)'))
+              end
+
+              describe '#switch_disconnected' do
+                When { switch_monitor.switch_disconnected(dpid3) }
+
+                context 'with 0xabc' do
+                  Given(:dpid3) { 0xabc }
+                  Then do
+                    expect(logger).to(have_received(:info).
+                                      with('0xabc is down (all = 0xdef)'))
+                  end
+                end
+              end
+            end
+          end
+        end
+      end
+    end
+  end
 end
diff --git a/tasks/reek.rake b/tasks/reek.rake
index 93861fe..8046ecf 100644
--- a/tasks/reek.rake
+++ b/tasks/reek.rake
@@ -3,7 +3,6 @@ begin
   Reek::Rake::Task.new do |t|
     t.fail_on_error = false
     t.verbose = false
-    t.reek_opts = '--quiet'
   end
 rescue LoadError
   task :reek do