diff --git a/.gitignore b/.gitignore
index b3823fa..6e3f348 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 *.gem
 coverage
 .shanty
+Gemfile.lock
diff --git a/.rubocop.yml b/.rubocop.yml
index 5721fc1..23954f6 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -9,3 +9,11 @@ LineLength:
 # problem.
 ModuleFunction:
   Enabled: False
+
+# FIXME: Only enabling because we are using the singleton pattern still for the
+# Env and TaskEnv classes and they store memoized values that need to be
+# preserved even after mixing in. Without class vars, this does not work. We
+# plan to refactor these singletons out and into class instances that are passed
+# around instead as needed.
+ClassVars:
+  Enabled: False
diff --git a/.travis.yml b/.travis.yml
index 4a79210..a7d6c7b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,19 @@
+sudo: false
 language: ruby
 rvm:
-  - 2.2.0
-notifications:
-  webhooks: https://hubot-shantytown.rhcloud.com/hubot/travis?room=#shantytow n
+  - 2.2.3
+
+# We have to install Rust manually, as Travis does not yet allow multiligual
+# builds. We install the latest stable Rust build.
+before_install:
+  - mkdir ~/rust-installer
+  - curl -sL https://static.rust-lang.org/rustup.sh -o ~/rust-installer/rustup.sh
+  - sh ~/rust-installer/rustup.sh --prefix=~/rust --spec=stable -y --disable-sudo 2> /dev/null
+  - export PATH=~/rust/bin:$PATH
+  - export LD_LIBRARY_PATH=~/rust/lib:$LD_LIBRARY_PATH
+  - rustc --version
+  - cargo --version
 script: bundle exec ./bin/shanty --trace test
+
+notifications:
+  webhooks: https://hubot-shantytown.rhcloud.com/hubot/travis?room=#shantytown
diff --git a/Gemfile.lock b/Gemfile.lock
index d579810..95a99bd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -4,94 +4,112 @@ PATH
     shanty (0.3.0)
       acts_as_graph_vertex (~> 1.0)
       algorithms (~> 0.6)
-      attr_combined_accessor (~> 1.0)
-      call_me_ruby (~> 1.0)
+      bundler (~> 1.10)
+      call_me_ruby (~> 1.1)
       commander (~> 4.3)
+      gitignore_rb (~> 0.2.2)
       i18n (~> 0.7)
+      shenanigans (~> 1.0)
 
 GEM
   remote: https://rubygems.org/
   specs:
     acts_as_graph_vertex (1.0.0)
     algorithms (0.6.1)
-    ast (2.0.0)
-    astrolabe (1.3.0)
-      parser (>= 2.2.0.pre.3, < 3.0)
-    attr_combined_accessor (1.0.0)
-    byebug (4.0.5)
+    ast (2.1.0)
+    astrolabe (1.3.1)
+      parser (~> 2.2)
+    builder (3.2.2)
+    byebug (5.0.0)
       columnize (= 0.9.0)
-    call_me_ruby (1.0.2)
+    call_me_ruby (1.1.1)
     coderay (1.1.0)
     columnize (0.9.0)
-    commander (4.3.4)
+    commander (4.3.5)
       highline (~> 1.7.2)
-    coveralls (0.8.1)
+    coveralls (0.8.2)
       json (~> 1.8)
       rest-client (>= 1.6.8, < 2)
       simplecov (~> 0.10.0)
       term-ansicolor (~> 1.3)
       thor (~> 0.19.1)
+    cucumber (2.1.0)
+      builder (>= 2.1.2)
+      cucumber-core (~> 1.3.0)
+      diff-lcs (>= 1.1.3)
+      gherkin3 (~> 3.1.0)
+      multi_json (>= 1.7.5, < 2.0)
+      multi_test (>= 0.1.2)
+    cucumber-core (1.3.0)
+      gherkin3 (~> 3.1.0)
     diff-lcs (1.2.5)
     docile (1.1.5)
     domain_name (0.5.24)
       unf (>= 0.0.5, < 1.0.0)
-    filewatcher (0.5.1)
+    ffi (1.9.10)
+    filewatcher (0.5.2)
       trollop (~> 2.0)
-    highline (1.7.2)
+    gherkin3 (3.1.1)
+    gitignore_rb (0.2.4)
+      ffi (~> 1.9)
+    highline (1.7.7)
     http-cookie (1.0.2)
       domain_name (~> 0.5)
     i18n (0.7.0)
-    json (1.8.2)
+    json (1.8.3)
     method_source (0.8.2)
-    mime-types (2.6.1)
+    mime-types (2.6.2)
+    multi_json (1.11.2)
+    multi_test (0.1.2)
     netrc (0.10.3)
-    parser (2.2.2.5)
+    parser (2.2.2.6)
       ast (>= 1.1, < 3.0)
     powerpack (0.1.1)
     pry (0.10.1)
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
-    pry-byebug (3.1.0)
-      byebug (~> 4.0)
+    pry-byebug (3.2.0)
+      byebug (~> 5.0)
       pry (~> 0.10)
     rainbow (2.0.0)
     rest-client (1.8.0)
       http-cookie (>= 1.0.2, < 2.0)
       mime-types (>= 1.16, < 3.0)
       netrc (~> 0.7)
-    rspec (3.2.0)
-      rspec-core (~> 3.2.0)
-      rspec-expectations (~> 3.2.0)
-      rspec-mocks (~> 3.2.0)
-    rspec-core (3.2.3)
-      rspec-support (~> 3.2.0)
-    rspec-expectations (3.2.1)
+    rspec (3.3.0)
+      rspec-core (~> 3.3.0)
+      rspec-expectations (~> 3.3.0)
+      rspec-mocks (~> 3.3.0)
+    rspec-core (3.3.2)
+      rspec-support (~> 3.3.0)
+    rspec-expectations (3.3.1)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.2.0)
-    rspec-mocks (3.2.1)
+      rspec-support (~> 3.3.0)
+    rspec-mocks (3.3.2)
       diff-lcs (>= 1.2.0, < 2.0)
-      rspec-support (~> 3.2.0)
-    rspec-support (3.2.2)
-    rubocop (0.31.0)
+      rspec-support (~> 3.3.0)
+    rspec-support (3.3.0)
+    rubocop (0.34.2)
       astrolabe (~> 1.3)
-      parser (>= 2.2.2.1, < 3.0)
+      parser (>= 2.2.2.5, < 3.0)
       powerpack (~> 0.1)
       rainbow (>= 1.99.1, < 3.0)
       ruby-progressbar (~> 1.4)
-    rubocop-rspec (1.3.0)
+    rubocop-rspec (1.3.1)
     ruby-prof (0.15.8)
     ruby-progressbar (1.7.5)
+    shenanigans (1.0.11)
     simplecov (0.10.0)
       docile (~> 1.1.0)
       json (~> 1.8)
       simplecov-html (~> 0.10.0)
     simplecov-html (0.10.0)
     slop (3.6.0)
-    term-ansicolor (1.3.0)
+    term-ansicolor (1.3.2)
       tins (~> 1.0)
     thor (0.19.1)
-    tins (1.5.2)
+    tins (1.6.0)
     trollop (2.1.2)
     unf (0.1.4)
       unf_ext
@@ -102,6 +120,7 @@ PLATFORMS
 
 DEPENDENCIES
   coveralls (~> 0.8)
+  cucumber (~> 2.1)
   filewatcher (~> 0.5)
   pry-byebug (~> 3.1)
   rspec (~> 3.2)
@@ -109,3 +128,6 @@ DEPENDENCIES
   rubocop-rspec (~> 1.3)
   ruby-prof (~> 0.15)
   shanty!
+
+BUNDLED WITH
+   1.10.6
diff --git a/examples/test-static-project-2/Shantyfile b/examples/test-static-project-2/Shantyfile
deleted file mode 100644
index f28e046..0000000
--- a/examples/test-static-project-2/Shantyfile
+++ /dev/null
@@ -1 +0,0 @@
-parent 'examples/test-static-project'
diff --git a/examples/test-static-project-2/test-static-project-3/Shantyfile b/examples/test-static-project-2/test-static-project-3/Shantyfile
deleted file mode 100644
index 44116f7..0000000
--- a/examples/test-static-project-2/test-static-project-3/Shantyfile
+++ /dev/null
@@ -1 +0,0 @@
-parent 'examples/test-static-project-2'
diff --git a/examples/test-static-project/Shantyfile b/examples/test-static-project/Shantyfile
deleted file mode 100644
index c468b15..0000000
--- a/examples/test-static-project/Shantyfile
+++ /dev/null
@@ -1,2 +0,0 @@
-option 'foo', 'bar'
-tag 'lux'
diff --git a/spec/lib/shanty/mixins/acts_as_graph_node_spec.rb b/features/support/env.rb
similarity index 100%
rename from spec/lib/shanty/mixins/acts_as_graph_node_spec.rb
rename to features/support/env.rb
diff --git a/lib/shanty/env.rb b/lib/shanty/env.rb
index 4345245..cda99b7 100644
--- a/lib/shanty/env.rb
+++ b/lib/shanty/env.rb
@@ -1,7 +1,10 @@
+require 'i18n'
 require 'logger'
 require 'pathname'
 require 'yaml'
 
+require 'shanty/project_tree'
+
 module Shanty
   #
   module Env
@@ -10,12 +13,17 @@ module Env
 
     CONFIG_FILE = '.shanty.yml'
 
+    # This must be defined first due to being a class var that isn't first
+    # first accessed with ||=.
+    @@config = nil
+
     def clear!
-      @logger = nil
-      @environment = nil
-      @build_number = nil
-      @root = nil
-      @config = nil
+      @@logger = nil
+      @@environment = nil
+      @@build_number = nil
+      @@root = nil
+      @@config = nil
+      @@project_tree = nil
     end
 
     def require!
@@ -27,26 +35,34 @@ def require!
     end
 
     def logger
-      @logger ||= Logger.new(STDOUT)
+      @@logger ||= Logger.new(STDOUT).tap do |logger|
+        logger.formatter = proc do |_, datetime, _, msg|
+          "#{datetime}: #{msg}\n"
+        end
+      end
     end
 
     def environment
-      @environment ||= ENV['SHANTY_ENV'] || 'local'
+      @@environment ||= ENV['SHANTY_ENV'] || 'local'
     end
 
     def build_number
-      @build_number ||= (ENV['SHANTY_BUILD_NUMBER'] || 1).to_i
+      @@build_number ||= (ENV['SHANTY_BUILD_NUMBER'] || 1).to_i
     end
 
     def root
-      @root ||= find_root
+      @@root ||= find_root
+    end
+
+    def project_tree
+      @@project_tree ||= ProjectTree.new(root)
     end
 
     def config
-      return @config unless @config.nil?
-      return @config = {} unless File.exist?(config_path)
+      return @@config unless @@config.nil?
+      return @@config = {} unless File.exist?(config_path)
       config = YAML.load_file(config_path) || {}
-      @config = config[environment] || {}
+      @@config = config[environment] || {}
     end
 
     private
@@ -66,11 +82,7 @@ def config_path
     end
 
     def find_root
-      if root_dir.nil?
-        fail "Could not find a #{CONFIG_FILE} file in this or any parent directories. \
-        Please run `shanty init` in the directory you want to be the root of your project structure."
-      end
-
+      fail I18n.t('missing_root', config_file: CONFIG_FILE) if root_dir.nil?
       root_dir
     end
 
diff --git a/lib/shanty/graph.rb b/lib/shanty/graph.rb
index 3463738..56e131e 100644
--- a/lib/shanty/graph.rb
+++ b/lib/shanty/graph.rb
@@ -12,12 +12,14 @@ class Graph
     extend Forwardable
     include Enumerable
 
-    def_delegators :@projects, :<<, :empty?, :length, :each, :values, :[], :inspect, :to_s
+    def_delegators :@projects, :<<, :empty?, :length, :each, :values, :[],
+                   :inspect, :to_s
 
     # Public: Initialise a Graph.
     #
     # project_path_trie -
-    # projects - An array of projects to use. These are expected to be pre-sorted and linked via the ProjectLinker.
+    # projects - An array of projects to use. These are expected to be
+    #            pre-sorted and linked via the ProjectLinker.
     def initialize(project_path_trie, projects)
       @project_path_trie = project_path_trie
       @projects = projects
@@ -41,8 +43,7 @@ def by_name(name)
     def all_with_tags(*tags)
       return [] if tags.empty?
       select do |project|
-        project_tags = project.tags.map(&:to_sym)
-        tags.map(&:to_sym).all? { |tag| project_tags.include?(tag) }
+        tags.map(&:to_sym).all? { |tag| project.all_tags.include?(tag) }
       end
     end
 
diff --git a/lib/shanty/plugin.rb b/lib/shanty/plugin.rb
index c955329..dfcabbc 100644
--- a/lib/shanty/plugin.rb
+++ b/lib/shanty/plugin.rb
@@ -1,103 +1,61 @@
+require 'call_me_ruby'
 require 'shanty/env'
 require 'shanty/project'
 
 module Shanty
   # Some basic functionality for every plugin.
-  module Plugin
+  class Plugin
+    include CallMeRuby
     include Env
 
-    def self.extended(plugin)
-      plugins << plugin
-    end
-
-    def self.plugins
+    def self.inherited(plugin_class)
       @plugins ||= []
+      @plugins << plugin_class.new
     end
 
-    #
-
-    def self.discover_all_projects # => [Project]
-      plugins.flat_map(&:wanted_projects).uniq
-    end
-
-    def self.with_graph(graph)
-      plugins.each do |plugin|
-        plugin.with_graph_callbacks.each { |callback| callback.call(graph) }
-      end
-    end
-
-    #
-
-    def callbacks
-      @callbacks ||= []
-    end
-
-    def tags
-      @tags ||= []
+    def self.all_projects
+      (@plugins || []).flat_map(&:projects).uniq
     end
 
-    def wanted_project_globs
-      @wanted_project_globs ||= []
+    def self.all_with_graph(graph)
+      (@plugins || []).each { |plugin| plugin.with_graph(graph) }
     end
 
-    def wanted_project_callbacks
-      @wanted_project_callbacks ||= []
+    def self.tags(*args)
+      (@tags ||= []).concat(args.map(&:to_sym))
     end
 
-    def with_graph_callbacks
-      @with_graph_callbacks ||= []
+    def self.projects(*globs_or_syms)
+      (@project_matchers ||= []).concat(globs_or_syms)
     end
 
-    #
-
-    def add_to_project(project)
-      project.singleton_class.include(self)
-      callbacks.each { |args| project.subscribe(*args) }
-      tags.each { |tag| project.tag(tag) }
+    def self.with_graph(&block)
+      (@with_graph_callbacks ||= []) << block
     end
 
-    #
-
-    def subscribe(*args)
-      callbacks << args
-    end
-
-    def adds_tags(*args)
-      tags.concat(args)
-    end
-
-    def wants_projects_matching(*globs, &block)
-      wanted_project_globs.concat(globs)
-      wanted_project_callbacks << block if block_given?
-    end
-
-    def with_graph(&block)
-      with_graph_callbacks << block
+    def projects
+      project_matchers = self.class.instance_variable_get(:@project_matchers)
+      return [] if project_matchers.nil? || project_matchers.empty?
+      (projects_from_globs(project_matchers) + projects_from_callbacks(project_matchers)).uniq.tap do |projects|
+        projects.each { |project| project.add_plugin(self) }
+      end
     end
 
-    #
-
-    def wanted_projects
-      (wanted_projects_from_globs + wanted_projects_from_callbacks).uniq.tap do |projects|
-        projects.each do |project|
-          project.plugin(self)
-        end
-      end
+    def with_graph(graph)
+      callbacks = self.class.instance_variable_get(:@with_graph_callbacks)
+      return [] if callbacks.nil? || callbacks.empty?
+      callbacks.each { |callback| callback.call(graph) }
     end
 
     private
 
-    def wanted_projects_from_globs
-      wanted_project_globs.flat_map do |globs|
-        # Will make the glob absolute to the root if (and only if) it is relative.
-        Dir[File.expand_path(globs, root)].map do |path|
-          Project.new(File.absolute_path(File.dirname(path)))
-        end
-      end
+    def projects_from_globs(project_matchers)
+      globs = project_matchers.find_all { |glob_or_sym| glob_or_sym.is_a?(String) }
+      project_tree.glob(*globs).map { |path| Project.new(File.absolute_path(File.dirname(path))) }
     end
 
-    def wanted_projects_from_callbacks
-      wanted_project_callbacks.flat_map(&:call)
+    def projects_from_callbacks(project_matchers)
+      project_matchers.find_all { |glob_or_sym| glob_or_sym.is_a?(Symbol) }.flat_map { |sym| send(sym) }
     end
   end
 end
diff --git a/lib/shanty/plugins/bundler_plugin.rb b/lib/shanty/plugins/bundler_plugin.rb
index 87cf10c..6499941 100644
--- a/lib/shanty/plugins/bundler_plugin.rb
+++ b/lib/shanty/plugins/bundler_plugin.rb
@@ -1,17 +1,18 @@
+require 'bundler'
 require 'shanty/plugin'
 
 module Shanty
   # Public: Bundler plugin for building ruby projects.
-  module BundlerPlugin
-    extend Plugin
-
-    adds_tags :bundler
-    wants_projects_matching '**/Gemfile'
+  class BundlerPlugin < Plugin
+    tags :bundler
+    projects '**/Gemfile'
     subscribe :build, :bundle_install
 
     def bundle_install
-      # FIXME: Add support for the --jobs argument to parallelise the bundler run.
-      system 'bundle install --quiet'
+      Bundler.with_clean_env do
+        # FIXME: Add support for the --jobs argument to parallelise the bundler run.
+        system 'bundle install --quiet'
+      end
     end
   end
 end
diff --git a/lib/shanty/plugins/cucumber_plugin.rb b/lib/shanty/plugins/cucumber_plugin.rb
new file mode 100644
index 0000000..72a2d65
--- /dev/null
+++ b/lib/shanty/plugins/cucumber_plugin.rb
@@ -0,0 +1,24 @@
+require 'shanty/plugin'
+
+module Shanty
+  # Public: Cucumber plugin for testing ruby projects.
+  class CucumberPlugin < Plugin
+    tags :cucumber
+    subscribe :test, :cucumber
+    # By default, we'll detect Cucumber in a project if has a dependency on it in a Gemfile or *.gemspec file. If you
+    # don't use these files, you'll need to import the plugin manually using a Shantyfile as we can't tell if RSpec is
+    # being used from the presence of a spec directory alone (this can be many other testing frameworks!)
+    projects :cucumber_projects
+
+    def cucumber_projects
+      project_tree.glob('**/{*.gemspec,Gemfile}').each_with_object([]) do |dependency_file, acc|
+        next unless File.read(dependency_file) =~ /['"]cucumber['"]/
+        acc << Project.new(File.absolute_path(File.dirname(dependency_file)))
+      end
+    end
+
+    def cucumber
+      system 'cucumber'
+    end
+  end
+end
diff --git a/lib/shanty/plugins/rspec_plugin.rb b/lib/shanty/plugins/rspec_plugin.rb
index 615dfda..6fd6366 100644
--- a/lib/shanty/plugins/rspec_plugin.rb
+++ b/lib/shanty/plugins/rspec_plugin.rb
@@ -2,22 +2,21 @@
 
 module Shanty
   # Public: Rspec plugin for testing ruby projects.
-  module RspecPlugin
-    extend Plugin
-
-    adds_tags :rspec
+  class RspecPlugin < Plugin
+    tags :rspec
+    subscribe :test, :rspec
     # By default, we'll detect RSpec in a project if has a dependency on it in a Gemfile or *.gemspec file. If you don't
     # use these files, you'll need to import the plugin manually using a Shantyfile as we can't tell if RSpec is being
     # used from the presence of a spec directory alone (this can be many other testing frameworks!)
-    wants_projects_matching do
-      Dir['**/{*.gemspec,Gemfile}'].each_with_object([]) do |dependency_file, acc|
+    projects :rspec_projects
+
+    def rspec_projects
+      project_tree.glob('**/{*.gemspec,Gemfile}').each_with_object([]) do |dependency_file, acc|
         next unless File.read(dependency_file) =~ /['"]rspec['"]/
         acc << Project.new(File.absolute_path(File.dirname(dependency_file)))
       end
     end
 
-    subscribe :test, :rspec
-
     def rspec
       system 'rspec'
     end
diff --git a/lib/shanty/plugins/rubocop_plugin.rb b/lib/shanty/plugins/rubocop_plugin.rb
index c817a14..1c7241c 100644
--- a/lib/shanty/plugins/rubocop_plugin.rb
+++ b/lib/shanty/plugins/rubocop_plugin.rb
@@ -2,11 +2,9 @@
 
 module Shanty
   # Public: Rubocop plugin for style checking ruby projects.
-  module RubocopPlugin
-    extend Plugin
-
-    adds_tags :rubocop
-    wants_projects_matching '**/.rubocop.yml'
+  class RubocopPlugin < Plugin
+    tags :rubocop
+    projects '**/.rubocop.yml'
     subscribe :test, :rubocop
 
     def rubocop
diff --git a/lib/shanty/plugins/rubygem_plugin.rb b/lib/shanty/plugins/rubygem_plugin.rb
index 3cbcb07..44519b9 100644
--- a/lib/shanty/plugins/rubygem_plugin.rb
+++ b/lib/shanty/plugins/rubygem_plugin.rb
@@ -2,11 +2,9 @@
 
 module Shanty
   # Public: Rubygem plugin for buildin gems.
-  module RubygemPlugin
-    extend Plugin
-
-    adds_tags :rubygem
-    wants_projects_matching '**/*.gemspec'
+  class RubygemPlugin < Plugin
+    tags :rubygem
+    projects '**/*.gemspec'
     subscribe :build, :build_gem
 
     def build_gem
diff --git a/lib/shanty/plugins/shantyfile_plugin.rb b/lib/shanty/plugins/shantyfile_plugin.rb
index 43a8665..e83128c 100644
--- a/lib/shanty/plugins/shantyfile_plugin.rb
+++ b/lib/shanty/plugins/shantyfile_plugin.rb
@@ -2,10 +2,16 @@
 
 module Shanty
   # Public: Plugin for finding all directories marked with a Shantyfile.
-  module ShantyfilePlugin
-    extend Plugin
+  class ShantyfilePlugin < Plugin
+    tags :shantyfile
+    projects :shantyfile_projects
 
-    adds_tags :shantyfile
-    wants_projects_matching '**/Shantyfile'
+    def shantyfile_projects
+      project_tree.glob('**/Shantyfile').map do |shantyfile_path|
+        Project.new(File.absolute_path(File.dirname(shantyfile_path))).tap do |project|
+          project.instance_eval(File.read(shantyfile_path), shantyfile_path)
+        end
+      end
+    end
   end
 end
diff --git a/lib/shanty/project.rb b/lib/shanty/project.rb
index 830ff3c..a6ea843 100644
--- a/lib/shanty/project.rb
+++ b/lib/shanty/project.rb
@@ -1,6 +1,6 @@
 require 'acts_as_graph_vertex'
-require 'attr_combined_accessor'
 require 'call_me_ruby'
+require 'pathname'
 
 require 'shanty/env'
 
@@ -8,11 +8,9 @@ module Shanty
   # Public: Represents a project in the current repository.
   class Project
     include ActsAsGraphVertex
-    include CallMeRuby
     include Env
 
-    attr_combined_accessor :name, :tags, :options
-    attr_accessor :path, :parents_by_path
+    attr_accessor :name, :path, :tags, :options
 
     # Multiton or Flyweight pattern - only allow once instance per unique path.
     #
@@ -36,37 +34,39 @@ def clear!
     #
     # path - The path to the project.
     def initialize(path)
-      fail('Path to project must be a directory.') unless File.directory?(path)
+      pathname = Pathname.new(File.expand_path(path, root))
+      fail('Path to project must be a directory.') unless pathname.directory?
 
       @path = path
 
       @name = File.basename(path)
-      @parents_by_path = []
+      @plugins = []
       @tags = []
       @options = {}
     end
 
-    def execute_shantyfile!
-      shantyfile_path = File.join(@path, 'Shantyfile')
-      return unless File.exist?(shantyfile_path)
-      instance_eval(File.read(shantyfile_path), shantyfile_path)
+    def add_plugin(plugin)
+      @plugins << plugin
     end
 
-    def plugin(plugin)
-      plugin.add_to_project(self)
+    def remove_plugin(plugin_class)
+      @plugins.delete_if { |plugin| plugin.is_a?(plugin_class) }
     end
 
-    def parent(parent)
-      # Will make the parent path absolute to the root if (and only if) it is relative.
-      @parents_by_path << File.expand_path(parent, root)
-    end
-
-    def tag(tag)
-      @tags << tag
+    # Public: The tags assigned to this project, and any tags provided by any
+    # plugins operating on this project.
+    #
+    # Returns an Array of symbols representing the tags on this project.
+    def all_tags
+      (@tags + @plugins.flat_map { |plugin| plugin.class.tags }).map(&:to_sym).uniq
     end
 
-    def option(key, value)
-      @options[key] = value
+    def publish(name, *args)
+      @plugins.each do |plugin|
+        next unless plugin.subscribed?(name)
+        logger.info("Executing #{name} on the #{plugin.class} plugin...")
+        return false if plugin.publish(name, *args) == false
+      end
     end
 
     # Public: The absolute paths to the artifacts that would be created by this
@@ -83,7 +83,7 @@ def artifact_paths
     #
     # Returns a simple String representation of this instance.
     def to_s
-      "#{name}"
+      name
     end
 
     # Public: Overriden String conversion method to return a more detailed
@@ -95,18 +95,10 @@ def inspect
       {
         name: @name,
         path: @path,
-        tags: @tags,
+        tags: all_tags,
         options: @options,
-        parents_by_path: @parents_by_path
+        parents: parents.map(&:path)
       }.inspect
     end
-
-    def within_project_dir
-      return unless block_given?
-
-      Dir.chdir(path) do
-        yield
-      end
-    end
   end
 end
diff --git a/lib/shanty/project_linker.rb b/lib/shanty/project_sorter.rb
similarity index 56%
rename from lib/shanty/project_linker.rb
rename to lib/shanty/project_sorter.rb
index 8604a7b..3f36793 100644
--- a/lib/shanty/project_linker.rb
+++ b/lib/shanty/project_sorter.rb
@@ -5,8 +5,8 @@
 require 'shanty/graph'
 
 module Shanty
-  # Public:
-  class ProjectLinker
+  # Public: Sorts projects using Tarjan's strongly connected components algorithm.
+  class ProjectSorter
     include TSort
 
     # Public: Initialise a ProjectLinker.
@@ -16,23 +16,12 @@ def initialize(projects)
       @projects = projects
     end
 
-    # Private: Given a list of projects, construct the parent/child
-    # relationships between them given a list of their parents/children by name
-    # as defined on the project instances.
+    # Private: Given a list of projects, sort them and construct a graph.
     #
-    # Returns a Graph with the projects linked and sorted.
-    def link
-      @projects.each do |project|
-        project.parents_by_path.each do |parent_path|
-          parent_dependency = project_path_trie.get(parent_path)
-          if parent_dependency.nil?
-            fail("Cannot find project at path #{parent_path}, which was specified as a dependency for #{project}")
-          end
-
-          project.add_parent(parent_dependency)
-        end
-      end
-
+    # The sorting uses Tarjan's strongly connected components algorithm.
+    #
+    # Returns a Graph with the projects sorted.
+    def sort
       Graph.new(project_path_trie, tsort)
     end
 
diff --git a/lib/shanty/project_tree.rb b/lib/shanty/project_tree.rb
new file mode 100644
index 0000000..d95783f
--- /dev/null
+++ b/lib/shanty/project_tree.rb
@@ -0,0 +1,45 @@
+module Shanty
+  # Public: Encapsulates the directory tree of a Shanty project. This provides a
+  # way to glob the project tree in a performant way without globing through
+  # files that are ignored by Git, SVN some other VCS.
+  #
+  # FIXME: The ignores are not implemented yet, this work has been recorded in
+  # issue #9 (https://github.com/shantytown/shanty/issues/9).
+  class ProjectTree
+    # Allow double globbing, and matching hidden files.
+    GLOB_FLAGS = File::FNM_EXTGLOB | File::FNM_DOTMATCH
+    # FIXME: Basic ignores until the .gitignore file can be loaded instead.
+    IGNORE_REGEX = /(vendor|.git)/
+
+    # Public: Initialise the ProjectTree instance.
+    #
+    # root - The absolute path to the root of the project within which any file
+    #        operations should be performed.
+    def initialize(root)
+      @root = root
+    end
+
+    # Public: Get the full list of files in the project tree, with any files
+    # ignored by Git, SVN or some other VCS removed from the list.
+    #
+    # Returns an Array of Strings where the strings are paths within the
+    # project.
+    def files
+      @files ||= Dir.glob(File.join(@root, '**/*'), GLOB_FLAGS).select do |path|
+        File.file?(path) && !(path =~ IGNORE_REGEX)
+      end
+    end
+
+    # Public: Get a list of the files in the project tree that match any of the
+    # given globs, with any files ignored by Git, SVN or some other VCS
+    # removed from the list.
+    #
+    # Returns an Array of Strings where the strings are paths within the
+    # project.
+    def glob(*globs)
+      files.find_all do |path|
+        globs.any? { |pattern| File.fnmatch(pattern, path, File::FNM_EXTGLOB) }
+      end
+    end
+  end
+end
diff --git a/lib/shanty/task_env.rb b/lib/shanty/task_env.rb
index c0790b6..0f71bba 100644
--- a/lib/shanty/task_env.rb
+++ b/lib/shanty/task_env.rb
@@ -1,5 +1,5 @@
 require 'shanty/plugin'
-require 'shanty/project_linker'
+require 'shanty/project_sorter'
 
 module Shanty
   #
@@ -12,11 +12,8 @@ def clear!
     end
 
     def graph
-      return @graph unless @graph.nil?
-
-      projects = Plugin.discover_all_projects.each(&:execute_shantyfile!)
-      @graph ||= ProjectLinker.new(projects).link.tap do |graph|
-        Plugin.with_graph(graph)
+      @graph ||= ProjectSorter.new(Plugin.all_projects).sort.tap do |graph|
+        Plugin.all_with_graph(graph)
       end
     end
   end
diff --git a/lib/shanty/task_sets/basic_task_set.rb b/lib/shanty/task_sets/basic_task_set.rb
index 98ac234..045798a 100644
--- a/lib/shanty/task_sets/basic_task_set.rb
+++ b/lib/shanty/task_sets/basic_task_set.rb
@@ -14,31 +14,39 @@ def init
     desc 'projects [--tags TAG,TAG,...]', 'tasks.projects.desc'
     option :tags, type: :array, desc: 'tasks.common.options.tags'
     def projects(options)
-      filtered_graph(options).each { |project| puts project }
+      filtered_graph(*tags_from_options(options)).each do |project|
+        puts "#{project.name} (#{project.path})#{project.tags.map { |tag| "\n  - #{tag}" }.join}"
+      end
     end
 
     desc 'build [--tags TAG,TAG,...]', 'tasks.build.desc'
     option :tags, type: :array, desc: 'tasks.common.options.tags'
     def build(options)
-      run_common_task(options, :build)
+      run_common_task(:build, *tags_from_options(options))
     end
 
     desc 'test [--tags TAG,TAG,...]', 'tasks.test.desc'
     option :tags, type: :array, desc: 'tasks.common.options.tags'
     def test(options)
-      run_common_task(options, :test)
+      run_common_task(:test, *tags_from_options(options))
     end
 
     private
 
-    def run_common_task(options, task)
-      filtered_graph(options).each do |project|
-        fail I18n.t("tasks.#{task}.failed", project: project) unless project.publish(task)
+    def tags_from_options(options)
+      (options.tags || '').split(',')
+    end
+
+    def run_common_task(task, *tags)
+      filtered_graph(*tags).each do |project|
+        Dir.chdir(project.path) do
+          fail I18n.t("tasks.#{task}.failed", project: project) unless project.publish(task)
+        end
       end
     end
 
-    def filtered_graph(options)
-      return scoped_graph.all_with_tags(*options.tags.split(',')) unless options.tags.nil?
+    def filtered_graph(*tags)
+      return scoped_graph.all_with_tags(*tags) unless tags.empty?
       scoped_graph
     end
 
diff --git a/shanty.gemspec b/shanty.gemspec
index be49f12..ca53658 100644
--- a/shanty.gemspec
+++ b/shanty.gemspec
@@ -21,13 +21,16 @@ Gem::Specification.new do |gem|
   gem.files = Dir['**/*'].select { |d| d =~ %r{^(README|bin/|ext/|lib/)} }
 
   gem.add_dependency 'acts_as_graph_vertex', '~>1.0'
+  gem.add_dependency 'bundler', '~>1.10'
   gem.add_dependency 'algorithms', '~>0.6'
-  gem.add_dependency 'attr_combined_accessor', '~>1.0'
-  gem.add_dependency 'call_me_ruby', '~>1.0'
+  gem.add_dependency 'call_me_ruby', '~>1.1'
   gem.add_dependency 'commander', '~>4.3'
+  gem.add_dependency 'gitignore_rb', '~>0.2.2'
   gem.add_dependency 'i18n', '~>0.7'
+  gem.add_dependency 'shenanigans', '~>1.0'
 
   gem.add_development_dependency 'coveralls', '~>0.8'
+  gem.add_development_dependency 'cucumber', '~>2.1'
   gem.add_development_dependency 'filewatcher', '~>0.5'
   gem.add_development_dependency 'pry-byebug', '~> 3.1'
   gem.add_development_dependency 'rspec', '~> 3.2'
diff --git a/spec/fixtures/test_plugin.rb b/spec/fixtures/test_plugin.rb
deleted file mode 100644
index 0553821..0000000
--- a/spec/fixtures/test_plugin.rb
+++ /dev/null
@@ -1,16 +0,0 @@
-require 'shanty/plugin'
-
-module Shanty
-  # Test Plugin fixture.
-  module TestPlugin
-    extend Plugin
-
-    adds_tags :test
-    subscribe :foo, :bar
-    subscribe :cats, :dogs, :rabies
-
-    def bar; end
-
-    def rabies; end
-  end
-end
diff --git a/spec/fixtures/test_project_with_plugin.rb b/spec/fixtures/test_project_with_plugin.rb
deleted file mode 100644
index 101306c..0000000
--- a/spec/fixtures/test_project_with_plugin.rb
+++ /dev/null
@@ -1,9 +0,0 @@
-require 'shanty/project'
-require_fixture 'test_plugin'
-
-module Shanty
-  # Test Project fixture which includes the test Plugin.
-  class TestProjectWithPlugin < Project
-    include TestPlugin
-  end
-end
diff --git a/spec/fixtures/test_unused_plugin.rb b/spec/fixtures/test_unused_plugin.rb
index 0fe009e..b488fdd 100644
--- a/spec/fixtures/test_unused_plugin.rb
+++ b/spec/fixtures/test_unused_plugin.rb
@@ -3,7 +3,5 @@
 module Shanty
   # Test unused Plugin fixture, used for testing whether looking plugins up by this plugin type, given none of them
   # have it included, returns nothing.
-  module UnusedPlugin
-    extend Plugin
-  end
+  class UnusedPlugin < Plugin; end
 end
diff --git a/spec/lib/shanty/env_spec.rb b/spec/lib/shanty/env_spec.rb
index ed88234..a232bb5 100644
--- a/spec/lib/shanty/env_spec.rb
+++ b/spec/lib/shanty/env_spec.rb
@@ -1,5 +1,6 @@
 require 'spec_helper'
 require 'fileutils'
+require 'i18n'
 require 'tmpdir'
 require 'shanty/env'
 
@@ -103,7 +104,7 @@ module Shanty
 
       it('throws an exception if no ancestor folders have a .shanty.yml file in them') do
         FileUtils.rm('.shanty.yml')
-        expect { subject.root }.to raise_error
+        expect { subject.root }.to raise_error(I18n.t('missing_root'))
       end
     end
 
diff --git a/spec/lib/shanty/graph_spec.rb b/spec/lib/shanty/graph_spec.rb
index 204765e..89724f6 100644
--- a/spec/lib/shanty/graph_spec.rb
+++ b/spec/lib/shanty/graph_spec.rb
@@ -3,9 +3,6 @@
 require 'shanty/graph'
 require 'shanty/project'
 
-require_fixture 'test_plugin'
-require_fixture 'test_unused_plugin'
-
 # Allows all classes to be refereneced without the module name
 module Shanty
   RSpec.describe(Graph) do
@@ -29,6 +26,10 @@ module Shanty
     end
 
     describe('#all_with_tags') do
+      before do
+        subject.first.tags << 'test'
+      end
+
       it('returns an empty array when no tags are given') do
         expect(subject.all_with_tags).to be_empty
       end
@@ -38,7 +39,7 @@ module Shanty
       end
 
       it('returns the correct projects when matching tags are given') do
-        expect(subject.all_with_tags('test')).to match_array(subject)
+        expect(subject.all_with_tags('test')).to match_array([subject.first])
       end
     end
 
diff --git a/spec/lib/shanty/plugin_spec.rb b/spec/lib/shanty/plugin_spec.rb
index 0e8c5cd..1dfa7f5 100644
--- a/spec/lib/shanty/plugin_spec.rb
+++ b/spec/lib/shanty/plugin_spec.rb
@@ -1,36 +1,125 @@
 require 'spec_helper'
 require 'shanty/plugin'
 
-require_fixture 'test_plugin'
-require_fixture 'test_project_with_plugin'
-
 # All classes referenced belong to the shanty project
 module Shanty
   RSpec.describe(Plugin) do
-    include_context('basics')
-    subject { TestPlugin }
-    let(:project) { TestProjectWithPlugin.new(project_path) }
-    let(:callbacks) { [%i(foo bar), %i(cats dogs rabies)] }
+    include_context('graph')
+    let(:graph) { double('graph') }
+    let(:plugin_class) do
+      Class.new(described_class) do
+        def foo
+          []
+        end
+      end
+    end
+    subject { plugin_class.new }
 
-    describe('.add_to_project') do
-      it('includes the plugin into the singleton class of the given project') do
-        expect(project.singleton_class).to receive(:include).with(subject)
+    around do |example|
+      plugins = described_class.instance_variable_get(:@plugins).clone
+      described_class.instance_variable_set(:@plugins, [subject])
+      example.run
+      described_class.instance_variable_set(:@plugins, plugins)
+    end
 
-        subject.add_to_project(project)
+    describe('.inherited') do
+      it('stores a new instance of any class that extends Plugin') do
+        expect(described_class.instance_variable_get(:@plugins).size).to eq(1)
+        expect(described_class.instance_variable_get(:@plugins).first).to be_instance_of(plugin_class)
       end
+    end
 
-      it('calls subscribe on the project for each callback in the plugin') do
-        callbacks.each do |callback|
-          expect(project).to receive(:subscribe).with(*callback)
-        end
+    describe('.all_projects') do
+      it('returns all the nominated projects from all the registered plugins') do
+        allow(subject).to receive(:projects).and_return(project)
+        expect(described_class.all_projects).to match_array(project)
+      end
+    end
+
+    describe('.all_with_graph') do
+      before do
+        described_class.instance_variable_set(:@plugins, [subject])
+      end
 
-        subject.add_to_project(project)
+      it('calls #with_graph on every registered plugin') do
+        expect(subject).to receive(:with_graph).with(graph)
+
+        described_class.all_with_graph(graph)
       end
     end
 
-    describe('.subscribe') do
-      it('stores all the given arguments in the callbacks') do
-        expect(subject.instance_variable_get(:@callbacks)).to contain_exactly(*callbacks)
+    describe('.tags') do
+      it('stores the given tags') do
+        plugin_class.tags(:foo, :marbles)
+
+        expect(plugin_class.instance_variable_get(:@tags)).to match_array([:foo, :marbles])
+      end
+
+      it('converts any given tags to symbols') do
+        plugin_class.tags('bar', 'lux')
+
+        expect(plugin_class.instance_variable_get(:@tags)).to match_array([:bar, :lux])
+      end
+    end
+
+    describe('.projects') do
+      it('stores the given globs or symbols') do
+        plugin_class.projects('**/foo', :bar)
+
+        expect(plugin_class.instance_variable_get(:@project_matchers)).to match_array(['**/foo', :bar])
+      end
+    end
+
+    describe('.with_graph') do
+      it('stores the passed block') do
+        block = proc {}
+        plugin_class.with_graph(&block)
+
+        expect(plugin_class.instance_variable_get(:@with_graph_callbacks)).to match_array([block])
+      end
+    end
+
+    describe('#projects') do
+      let(:project_tree) { double('project_tree') }
+
+      it('returns no projects if there are no matchers') do
+        expect(subject.projects).to be_empty
+      end
+
+      it('returns projects matching any stored globs') do
+        paths = project_paths.values.map { |p| File.join(p, 'foo') }
+        plugin_class.projects('**/foo', '**/bar')
+        allow(subject).to receive(:project_tree).and_return(project_tree)
+        allow(project_tree).to receive(:glob).with('**/foo', '**/bar').and_return(paths)
+
+        expect(subject.projects).to match_array(projects.values)
+      end
+
+      it('returns projects provided by the stored callbacks') do
+        allow(subject).to receive(:foo).and_return(projects.values)
+        plugin_class.projects(:foo)
+
+        expect(subject.projects).to match_array(projects.values)
+      end
+
+      it('adds the current plugin to the project') do
+        allow(subject).to receive(:foo).and_return([project])
+        plugin_class.projects(:foo)
+
+        expect(project).to receive(:add_plugin).with(subject)
+
+        subject.projects
+      end
+    end
+
+    describe('#with_graph') do
+      it('calls the stored callbacks with the given graph') do
+        block = proc {}
+        plugin_class.with_graph(&block)
+
+        expect(block).to receive(:call).with(graph)
+
+        subject.with_graph(graph)
       end
     end
   end
diff --git a/spec/lib/shanty/plugins/bundler_plugin_spec.rb b/spec/lib/shanty/plugins/bundler_plugin_spec.rb
index 0f05f7b..32c14b2 100644
--- a/spec/lib/shanty/plugins/bundler_plugin_spec.rb
+++ b/spec/lib/shanty/plugins/bundler_plugin_spec.rb
@@ -5,10 +5,17 @@
 module Shanty
   RSpec.describe(BundlerPlugin) do
     include_context('basics')
-    subject { Class.new { include BundlerPlugin }.new }
+
+    it('adds the bundler tag') do
+      expect(described_class).to add_tags(:bundler)
+    end
+
+    it('finds projects that have a Gemfile') do
+      expect(described_class).to define_projects.with('**/Gemfile')
+    end
 
     it('subscribes to the build event') do
-      expect(BundlerPlugin.callbacks).to include([:build, :bundle_install])
+      expect(described_class).to subscribe_to(:build).with(:bundle_install)
     end
 
     describe('#bundle_install') do
diff --git a/spec/lib/shanty/plugins/cucumber_plugin_spec.rb b/spec/lib/shanty/plugins/cucumber_plugin_spec.rb
new file mode 100644
index 0000000..ed741c4
--- /dev/null
+++ b/spec/lib/shanty/plugins/cucumber_plugin_spec.rb
@@ -0,0 +1,29 @@
+require 'spec_helper'
+require 'shanty/plugins/cucumber_plugin'
+
+# All classes referenced belong to the shanty project
+module Shanty
+  RSpec.describe(CucumberPlugin) do
+    include_context('basics')
+
+    it('adds the cucumber tag') do
+      expect(described_class).to add_tags(:cucumber)
+    end
+
+    it('finds projects by calling a method to locate the ones that depend on Cucumber') do
+      expect(described_class).to define_projects.with(:cucumber_projects)
+    end
+
+    it('subscribes to the test event') do
+      expect(described_class).to subscribe_to(:test).with(:cucumber)
+    end
+
+    describe('#cucumber') do
+      it('calls cucumber') do
+        expect(subject).to receive(:system).with('cucumber')
+
+        subject.cucumber
+      end
+    end
+  end
+end
diff --git a/spec/lib/shanty/plugins/rspec_plugin_spec.rb b/spec/lib/shanty/plugins/rspec_plugin_spec.rb
index dfba60e..06c3ae0 100644
--- a/spec/lib/shanty/plugins/rspec_plugin_spec.rb
+++ b/spec/lib/shanty/plugins/rspec_plugin_spec.rb
@@ -5,10 +5,17 @@
 module Shanty
   RSpec.describe(RspecPlugin) do
     include_context('basics')
-    subject { Class.new { include RspecPlugin }.new }
+
+    it('adds the rspec tag') do
+      expect(described_class).to add_tags(:rspec)
+    end
+
+    it('finds projects by calling a method to locate the ones that depend on RSpec') do
+      expect(described_class).to define_projects.with(:rspec_projects)
+    end
 
     it('subscribes to the test event') do
-      expect(RspecPlugin.callbacks).to include([:test, :rspec])
+      expect(described_class).to subscribe_to(:test).with(:rspec)
     end
 
     describe('#rspec') do
diff --git a/spec/lib/shanty/plugins/rubocop_plugin_spec.rb b/spec/lib/shanty/plugins/rubocop_plugin_spec.rb
index d235827..e7f1507 100644
--- a/spec/lib/shanty/plugins/rubocop_plugin_spec.rb
+++ b/spec/lib/shanty/plugins/rubocop_plugin_spec.rb
@@ -5,10 +5,17 @@
 module Shanty
   RSpec.describe(RubocopPlugin) do
     include_context('basics')
-    subject { Class.new { include RubocopPlugin }.new }
+
+    it('adds the rubocop tag') do
+      expect(described_class).to add_tags(:rubocop)
+    end
+
+    it('finds projects that have a .rubocop.yml file') do
+      expect(described_class).to define_projects.with('**/.rubocop.yml')
+    end
 
     it('subscribes to the test event') do
-      expect(RubocopPlugin.callbacks).to include([:test, :rubocop])
+      expect(described_class).to subscribe_to(:test).with(:rubocop)
     end
 
     describe('#rubocop') do
diff --git a/spec/lib/shanty/plugins/rubygem_plugin_spec.rb b/spec/lib/shanty/plugins/rubygem_plugin_spec.rb
index 0f5f745..453e72e 100644
--- a/spec/lib/shanty/plugins/rubygem_plugin_spec.rb
+++ b/spec/lib/shanty/plugins/rubygem_plugin_spec.rb
@@ -5,10 +5,17 @@
 module Shanty
   RSpec.describe(RubygemPlugin) do
     include_context('basics')
-    subject { Class.new { include RubygemPlugin }.new }
 
-    it('subscribes to the test event') do
-      expect(RubygemPlugin.callbacks).to include([:build, :build_gem])
+    it('adds the rubygem tag') do
+      expect(described_class).to add_tags(:rubygem)
+    end
+
+    it('finds projects that have a *.gemspec file') do
+      expect(described_class).to define_projects.with('**/*.gemspec')
+    end
+
+    it('subscribes to the build event') do
+      expect(described_class).to subscribe_to(:build).with(:build_gem)
     end
 
     describe('#build_gem') do
diff --git a/spec/lib/shanty/plugins/shantyfile_plugin_spec.rb b/spec/lib/shanty/plugins/shantyfile_plugin_spec.rb
new file mode 100644
index 0000000..a25faa0
--- /dev/null
+++ b/spec/lib/shanty/plugins/shantyfile_plugin_spec.rb
@@ -0,0 +1,39 @@
+require 'spec_helper'
+require 'shanty/plugins/shantyfile_plugin'
+
+# All classes referenced belong to the shanty project
+module Shanty
+  RSpec.describe(ShantyfilePlugin) do
+    include_context('graph')
+
+    it('adds the shantyfile tag') do
+      expect(described_class).to add_tags(:shantyfile)
+    end
+
+    it('finds projects by calling a method to locate the ones that have a Shantyfile') do
+      expect(described_class).to define_projects.with(:shantyfile_projects)
+    end
+
+    describe('#shantyfile_projects') do
+      it('finds all projects with a Shantyfile') do
+        FileUtils.touch(File.join(project_paths[:one], 'Shantyfile'))
+        FileUtils.touch(File.join(project_paths[:three], 'Shantyfile'))
+
+        expect(subject.shantyfile_projects).to match_array([
+          projects[:one],
+          projects[:three]
+        ])
+      end
+
+      it('executes the found Shantyfiles within the context of the project') do
+        File.write(File.join(project_paths[:one], 'Shantyfile'), 'instance_variable_set(:@this_is_a_test, "foo")')
+        File.write(File.join(project_paths[:three], 'Shantyfile'), 'instance_variable_set(:@this_is_a_test, "bar")')
+
+        subject.shantyfile_projects
+
+        expect(projects[:one].instance_variable_get(:@this_is_a_test)).to eq('foo')
+        expect(projects[:three].instance_variable_get(:@this_is_a_test)).to eq('bar')
+      end
+    end
+  end
+end
diff --git a/spec/lib/shanty/project_linker_spec.rb b/spec/lib/shanty/project_linker_spec.rb
deleted file mode 100644
index d115d7b..0000000
--- a/spec/lib/shanty/project_linker_spec.rb
+++ /dev/null
@@ -1,50 +0,0 @@
-require 'spec_helper'
-require 'tmpdir'
-require 'shanty/graph'
-require 'shanty/project'
-
-require_fixture 'test_plugin'
-require_fixture 'test_unused_plugin'
-
-# Allows all classes to be refereneced without the module name
-module Shanty
-  RSpec.describe(ProjectLinker) do
-    include_context('graph')
-    subject { ProjectLinker.new(projects.values) }
-
-    describe('#link') do
-      let(:missing_parent) { 'foo-bar-does-not-exist' }
-
-      it('throws an exception if any of the projects have a dependency on a project that does not exist') do
-        project.parent(missing_parent)
-
-        expect { subject.link }.to raise_error("Cannot find project at path #{File.join(root, missing_parent)}, which \
-was specified as a dependency for shanty")
-      end
-
-      it('returns a graph with the projects linked together in parent relationships') do
-        graph = subject.link
-
-        expect(graph[0].parents.map(&:path)).to eql([])
-        expect(graph[1].parents.map(&:path)).to eql([project_paths[:one]])
-        expect(graph[2].parents.map(&:path)).to eql([project_paths[:two]])
-      end
-
-      it('returns a graph with the projects linked together in child relationships') do
-        graph = subject.link
-
-        expect(graph[0].children.map(&:path)).to eql([project_paths[:two]])
-        expect(graph[1].children.map(&:path)).to eql([project_paths[:three]])
-        expect(graph[2].children.map(&:path)).to eql([])
-      end
-
-      it("returns a graph with the projects sorted using Tarjan's strongly connected components algorithm") do
-        graph = subject.link
-
-        expect(graph[0].path).to equal(project_paths[:one])
-        expect(graph[1].path).to equal(project_paths[:two])
-        expect(graph[2].path).to equal(project_paths[:three])
-      end
-    end
-  end
-end
diff --git a/spec/lib/shanty/project_sorter_spec.rb b/spec/lib/shanty/project_sorter_spec.rb
new file mode 100644
index 0000000..85ac155
--- /dev/null
+++ b/spec/lib/shanty/project_sorter_spec.rb
@@ -0,0 +1,24 @@
+require 'spec_helper'
+require 'tmpdir'
+require 'shanty/project_sorter'
+
+# Allows all classes to be refereneced without the module name
+module Shanty
+  RSpec.describe(ProjectSorter) do
+    include_context('graph')
+    subject { ProjectSorter.new(projects.values) }
+
+    describe('#sort') do
+      it("returns a graph with the projects sorted using Tarjan's strongly connected components algorithm") do
+        projects[:two].add_parent(projects[:one])
+        projects[:three].add_parent(projects[:two])
+
+        graph = subject.sort
+
+        expect(graph[0].path).to eql(project_paths[:one])
+        expect(graph[1].path).to eql(project_paths[:two])
+        expect(graph[2].path).to eql(project_paths[:three])
+      end
+    end
+  end
+end
diff --git a/spec/lib/shanty/project_spec.rb b/spec/lib/shanty/project_spec.rb
index 7b2982c..d6d3e43 100644
--- a/spec/lib/shanty/project_spec.rb
+++ b/spec/lib/shanty/project_spec.rb
@@ -1,42 +1,86 @@
 require 'spec_helper'
 require 'shanty/project'
 
-require_fixture 'test_plugin'
-
 # All classes referenced belong to the shanty project
 module Shanty
   RSpec.describe(Project) do
     include_context('graph')
     subject { Shanty::Project.new(project_path) }
 
-    describe('#plugin') do
-      it('calls to the plugin to add it to the project') do
-        expect(Shanty::TestPlugin).to receive(:add_to_project).with(subject)
-        subject.plugin(Shanty::TestPlugin)
-      end
-    end
-
     describe('#name') do
-      it('returns the name from the project template in the constructor') do
-        expect(subject.name).to eql('shanty')
+      it('returns the name from the project in the constructor') do
+        expect(subject.name).to eql('one')
       end
     end
 
     describe('#path') do
-      it('returns the path from the project template in the constructor') do
+      it('returns the path from the project in the constructor') do
         expect(subject.path).to eql(project_path)
       end
     end
 
+    describe('#tags') do
+      it('defaults the tags to an empty array') do
+        expect(subject.tags).to eql([])
+      end
+    end
+
     describe('#options') do
       it('defaults the options to an empty object') do
         expect(subject.options).to eql({})
       end
     end
 
-    describe('#parents_by_path') do
-      it('defaults the parents to an empty array') do
-        expect(subject.parents_by_path).to eql([])
+    describe('#add_plugin') do
+      it('adds the given plugin to the project') do
+        plugin = double('plugin')
+
+        subject.add_plugin(plugin)
+
+        expect(subject.instance_variable_get(:@plugins)).to match_array([plugin])
+      end
+    end
+
+    describe('#remove_plugin') do
+      it('removes any plugins of the given class') do
+        plugin_class = Class.new
+        plugin = plugin_class.new
+        subject.instance_variable_set(:@plugins, [plugin])
+
+        subject.remove_plugin(plugin_class)
+
+        expect(subject.instance_variable_get(:@plugins)).to eql([])
+      end
+    end
+
+    describe('#publish') do
+      before { subject.add_plugin(plugin) }
+      let(:plugin) { double('plugin') }
+
+      it('skips over any plugins that are not subscribed to the event') do
+        allow(plugin).to receive(:subscribed?).and_return(false)
+
+        subject.publish(:foo)
+
+        expect(subject).to_not receive(:publish)
+      end
+
+      it('publishes the event on any listening plugins') do
+        allow(plugin).to receive(:subscribed?).and_return(true)
+
+        expect(plugin).to receive(:publish).with(:foo, :bar, :lux)
+
+        subject.publish(:foo, :bar, :lux)
+      end
+
+      it('returns false early if any of the plugin publishes return false') do
+        next_plugin = double('next plugin')
+        project.add_plugin(next_plugin)
+        allow(plugin).to receive(:subscribed?).and_return(true)
+        expect(plugin).to receive(:publish).and_return(false)
+
+        expect(subject.publish(:foo)).to be(false)
+        expect(next_plugin).to_not receive(:subscribed?)
       end
     end
 
@@ -48,46 +92,20 @@ module Shanty
 
     describe('#to_s') do
       it('returns a simple string representation of the project') do
-        expect(subject.to_s).to eql('shanty')
+        expect(subject.to_s).to eql('one')
       end
     end
 
     describe('#inspect') do
       it('returns a detailed string representation of the project') do
         expect(subject.inspect).to eql({
-          name: 'shanty',
+          name: 'one',
           path: project_path,
           tags: [],
           options: {},
-          parents_by_path: []
+          parents: []
         }.inspect)
       end
     end
-
-    describe('#within_project_dir') do
-      it('does nothing if there is no block given') do
-        expect(Dir).to_not receive(:chdir)
-
-        subject.within_project_dir
-      end
-
-      it('yields the given block') do
-        expect { |b| subject.within_project_dir(&b) }.to yield_with_no_args
-      end
-
-      it('yields the given block with the correct working directory') do
-        subject.within_project_dir do
-          expect(Dir.pwd).to eql(project_path)
-        end
-      end
-
-      it('changes the working directory back at the end') do
-        expected_pwd = Dir.pwd
-
-        subject.within_project_dir
-
-        expect(Dir.pwd).to eql(expected_pwd)
-      end
-    end
   end
 end
diff --git a/spec/lib/shanty/project_tree_spec.rb b/spec/lib/shanty/project_tree_spec.rb
new file mode 100644
index 0000000..cb63e5e
--- /dev/null
+++ b/spec/lib/shanty/project_tree_spec.rb
@@ -0,0 +1,42 @@
+require 'spec_helper'
+require 'shanty/plugin'
+
+# All classes referenced belong to the shanty project
+module Shanty
+  RSpec.describe(ProjectTree) do
+    include_context('basics')
+    subject { described_class.new(root) }
+
+    before do
+      [
+        File.join(project_paths[:one], 'Shantyfile'),
+        # FIXME: Right now, the ignores are not procesed. This will be
+        # implemented as part of issue #9.
+        # File.join(project_paths[:two], 'ignored'),
+        File.join(project_paths[:three], 'Shantyfile')
+      ].each { |path| FileUtils.touch(path) }
+
+      File.write(File.join(root, '.gitignore'), 'ignored')
+    end
+
+    describe('#files') do
+      it('returns all the files within the root') do
+        expect(subject.files).to match_array([
+          File.join(root, '.shanty.yml'),
+          File.join(root, '.gitignore'),
+          File.join(project_paths[:one], 'Shantyfile'),
+          File.join(project_paths[:three], 'Shantyfile')
+        ])
+      end
+    end
+
+    describe('#glob') do
+      it('returns all the files within the root that match any of the given globs') do
+        expect(subject.glob('**/Shantyfile', 'badglob')).to match_array([
+          File.join(project_paths[:one], 'Shantyfile'),
+          File.join(project_paths[:three], 'Shantyfile')
+        ])
+      end
+    end
+  end
+end
diff --git a/spec/lib/shanty/task_env_spec.rb b/spec/lib/shanty/task_env_spec.rb
index 2bf5c49..accf343 100644
--- a/spec/lib/shanty/task_env_spec.rb
+++ b/spec/lib/shanty/task_env_spec.rb
@@ -8,7 +8,7 @@ module Shanty
 
     describe('#graph') do
       it('discovers all the projects') do
-        expect(Plugin).to receive(:discover_all_projects).and_return([])
+        expect(Plugin).to receive(:all_projects).and_return([])
 
         subject.graph
       end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index 2ed322e..29fd119 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,23 +1,37 @@
 require 'coveralls'
 Coveralls.wear!
 
+require 'fileutils'
 require 'i18n'
+require 'logger'
+require 'pathname'
+require 'tmpdir'
 require 'shanty/env'
 require 'shanty/graph'
 require 'shanty/project'
 require 'shanty/task_env'
 require 'shanty/plugins/rspec_plugin'
 require 'shanty/plugins/rubocop_plugin'
+require 'shanty/plugins/shantyfile_plugin'
 
 def require_fixture(path)
   require File.join(__dir__, 'fixtures', path)
 end
 
-require_fixture 'test_plugin'
+def require_matchers(path)
+  require File.join(__dir__, 'support', 'matchers', path)
+end
+
+require_matchers 'call_me_ruby'
+require_matchers 'plugin'
 
 I18n.enforce_available_locales = false
 
 RSpec.configure do |config|
+  config.expect_with :rspec do |c|
+    c.include_chain_clauses_in_custom_matcher_descriptions = true
+  end
+
   config.mock_with(:rspec) do |mocks|
     mocks.verify_partial_doubles = true
   end
@@ -26,34 +40,49 @@ def require_fixture(path)
     Shanty::Env.clear!
     Shanty::TaskEnv.clear!
     Shanty::Project.clear!
+
+    Shanty::Env.logger.level = Logger::FATAL
   end
 end
 
 RSpec.shared_context('basics') do
-  let(:root) { File.expand_path(File.join(__dir__, '..')) }
+  around do |example|
+    FileUtils.touch(File.join(root, '.shanty.yml'))
+    project_paths.values.each do |project_path|
+      FileUtils.mkdir_p(project_path)
+    end
+
+    Dir.chdir(root) do
+      example.run
+    end
+
+    FileUtils.rm_rf(root)
+  end
+
+  # We have to use `realpath` for this as, at least on Mac OS X, the temporary
+  # dir path that is returned is actually a symlink. Shanty resolves this
+  # internally, so if we want to compare to any of the paths correctly we'll
+  # need to resolve it too.
+  let(:root) { Pathname.new(Dir.mktmpdir('shanty-test')).realpath }
   let(:project_paths) do
     {
-      three: File.join(root, 'examples', 'test-static-project-2', 'test-static-project-3'),
-      two: File.join(root, 'examples', 'test-static-project-2'),
-      one: File.join(root, 'examples', 'test-static-project'),
-      shanty: File.join(root)
+      one: File.join(root, 'one'),
+      two: File.join(root, 'two'),
+      three: File.join(root, 'two', 'three')
     }
   end
-  let(:project_path) { project_paths[:shanty] }
+  let(:project_path) { project_paths[:one] }
 end
 
 RSpec.shared_context('graph') do
   include_context('basics')
 
   let(:projects) do
-    Hash[project_paths.map do |key, project_path|
-      [key, Shanty::Project.new(project_path).tap do |project|
-        project.plugin(Shanty::TestPlugin)
-        project.execute_shantyfile!
-      end]
-    end]
+    project_paths.each_with_object({}) do |(key, project_path), acc|
+      acc[key] = Shanty::Project.new(project_path)
+    end
   end
-  let(:project) { projects[:shanty] }
+  let(:project) { projects[:one] }
   let(:project_path_trie) do
     Containers::Trie.new.tap do |trie|
       projects.values.map { |project| trie[project.path] = project }
diff --git a/spec/support/matchers/call_me_ruby.rb b/spec/support/matchers/call_me_ruby.rb
new file mode 100644
index 0000000..3ac18d0
--- /dev/null
+++ b/spec/support/matchers/call_me_ruby.rb
@@ -0,0 +1,12 @@
+# Something, something, darkside.
+module Shanty
+  RSpec::Matchers.define(:subscribe_to) do |event|
+    match do |actual|
+      expect(actual.instance_variable_get(:@class_callbacks)).to include(event => @callbacks)
+    end
+
+    chain(:with) do |*callbacks|
+      @callbacks = callbacks
+    end
+  end
+end
diff --git a/spec/support/matchers/plugin.rb b/spec/support/matchers/plugin.rb
new file mode 100644
index 0000000..d411f13
--- /dev/null
+++ b/spec/support/matchers/plugin.rb
@@ -0,0 +1,18 @@
+# Something, something, darkside.
+module Shanty
+  RSpec::Matchers.define(:add_tags) do |*tags|
+    match do |actual|
+      expect(actual.instance_variable_get(:@tags)).to include(*tags)
+    end
+  end
+
+  RSpec::Matchers.define(:define_projects) do
+    match do |actual|
+      expect(actual.instance_variable_get(:@project_matchers)).to include(*(@matchers || []))
+    end
+
+    chain :with do |*matchers|
+      @matchers = matchers
+    end
+  end
+end
diff --git a/translations/en.yml b/translations/en.yml
index 1391868..294aff6 100644
--- a/translations/en.yml
+++ b/translations/en.yml
@@ -1,5 +1,6 @@
 ---
 en:
+  missing_root: Could not find a %{config_file} file in this or any parent directories. Please run `shanty init` in the directory you want to be the root of your project structure
   tasks:
     common:
       options: