Reduce zombifier

* And add a full specification

bin/mutant

@@ -10,7 +10,23 @@ require 'mutant'
 namespace =
   if ARGV.include?('--zombie')
     $stderr.puts('Running mutant zombified!')
-    Mutant.zombify
+    Mutant::Zombifier.call(
+      namespace:        :Zombie,
+      load_path:        $LOAD_PATH,
+      kernel:           Kernel,
+      pathname:         Pathname,
+      require_highjack: Mutant::RequireHighjack.method(:call).to_proc.curry.call(Kernel),
+      root_require:     'mutant',
+      includes: %w[
+        mutant
+        unparser
+        morpher
+        adamantium
+        equalizer
+        anima
+        concord
+      ]
+    )
     Zombie::Mutant
   else
     Mutant

config/flay.yml

@@ -1,3 +1,3 @@
 ---
 threshold: 18
-total_score: 1240
+total_score: 1227

config/reek.yml

@@ -46,8 +46,7 @@ NestedIterators:
   - Mutant::Mutator::Util::Array::Element#dispatch
   - Mutant::Mutator::Node::Resbody#mutate_captures
   - Mutant::Mutator::Node::Arguments#emit_argument_mutations
-  - Mutant::RequireHighjack#infect
-  - Mutant::RequireHighjack#disinfect
+  - Mutant::RequireHighjack#self.call
   - Mutant::Selector::Expression#call
   - Mutant::Parallel::Master#run
   - Parser::Lexer#self.new

lib/mutant.rb

@@ -24,11 +24,8 @@ Thread.abort_on_exception = true
 
 # Library namespace
 module Mutant
-  # The frozen empty string used within mutant
-  EMPTY_STRING = ''.freeze
-  # The frozen empty array used within mutant
-  EMPTY_ARRAY = [].freeze
-
+  EMPTY_STRING   = ''.freeze
+  EMPTY_ARRAY    = [].freeze
   SCOPE_OPERATOR = '::'.freeze
 
   # Test if CI is detected via environment
@@ -41,17 +38,6 @@ module Mutant
     ENV.key?('CI')
   end
 
-  # Perform self zombification
-  #
-  # @return [self]
-  #
-  # @api private
-  #
-  def self.zombify
-    Zombifier.run('mutant', :Zombie)
-    self
-  end
-
   # Define instance of subclassed superclass as constant
   #
   # @param [Class] superclass
@@ -216,7 +202,6 @@ require 'mutant/reporter/cli/printer/test_result'
 require 'mutant/reporter/cli/tput'
 require 'mutant/reporter/cli/format'
 require 'mutant/zombifier'
-require 'mutant/zombifier/file'
 
 module Mutant
   # Reopen class to initialize constant to avoid dep circle

lib/mutant/require_highjack.rb

@@ -1,62 +1,23 @@
 module Mutant
   # Require highjack
-  class RequireHighjack
-    include Concord.new(:target, :callback)
+  module RequireHighjack
 
-    # Return original method
+    # Install require callback
+    #
+    # @param [Module] target
+    # @param [#call] callback
     #
     # @return [#call]
+    #   the original implementation on singleton
     #
     # @api private
     #
-    attr_reader :original
-
-    # Run block with highjacked require
-    #
-    # @return [self]
-    #
-    # @api private
-    #
-    def run
-      infect
-      yield
-      self
-    ensure
-      disinfect
-    end
-
-    # Infect kernel with highjack
-    #
-    # @return [self]
-    #
-    # @api private
-    #
-    def infect
-      callback = @callback
-      @original = target.method(:require)
-      target.module_eval do
-        undef :require
-        define_method(:require) do |logical_name|
-          callback.call(logical_name)
+    def self.call(target, callback)
+      target.method(:require).tap do
+        target.module_eval do
+          define_method(:require, &callback)
+          public :require
         end
-        module_function :require
-      end
-    end
-
-    # Imperfectly disinfect kernel from highjack
-    #
-    # @return [self]
-    #
-    # @api private
-    #
-    def disinfect
-      original = @original
-      target.module_eval do
-        undef :require
-        define_method(:require) do |logical_name|
-          original.call(logical_name)
-        end
-        module_function :require
       end
     end
 

lib/mutant/zombifier.rb

@@ -1,20 +1,19 @@
 module Mutant
   # Zombifier namespace
   class Zombifier
-    include Adamantium::Flat, Concord.new(:namespace)
+    include Anima.new(
+      :includes,
+      :namespace,
+      :load_path,
+      :kernel,
+      :require_highjack,
+      :root_require,
+      :pathname
+    )
 
-    # Excluded into zombification
-    includes = %w[
-      mutant
-      unparser
-      morpher
-      adamantium
-      equalizer
-      anima
-      concord
-    ]
+    include AST::Sexp
 
-    INCLUDES = %r{\A#{Regexp.union(includes)}(?:/.*)?\z}.freeze
+    LoadError = Class.new(::LoadError)
 
     # Initialize object
     #
@@ -24,37 +23,28 @@ module Mutant
     #
     # @api private
     #
-    def initialize(namespace)
+    def initialize(*)
+      super
+      @includes = %r{\A#{Regexp.union(includes)}(?:/.*)?\z}
       @zombified = Set.new
-      @highjack = RequireHighjack.new(Kernel, method(:require))
-      super(namespace)
     end
 
-    # Perform zombification of target library
-    #
-    # @param [String] logical_name
-    # @param [Symbol] namespace
-    #
-    # @return [self]
-    #
-    # @api private
-    #
-    def self.run(logical_name, namespace)
-      new(namespace).run(logical_name)
+    def self.call(*args)
+      new(*args).__send__(:call)
       self
     end
 
+  private
+
     # Run zombifier
     #
-    # @param [String] logical_name
-    #
     # @return [undefined]
     #
     # @api private
     #
-    def run(logical_name)
-      @highjack.infect
-      require(logical_name)
+    def call
+      @original = require_highjack.call(method(:require))
+      require(root_require)
     end
 
     # Test if logical name is subjected to zombification
@@ -64,25 +54,77 @@ module Mutant
     # @api private
     #
     def include?(logical_name)
-      !@zombified.include?(logical_name) && INCLUDES =~ logical_name
+      !@zombified.include?(logical_name) && @includes =~ logical_name
     end
 
     # Require file in zombie namespace
     #
     # @param [#to_s] logical_name
     #
-    # @return [self]
+    # @return [undefined]
     #
     # @api private
     #
     def require(logical_name)
       logical_name = logical_name.to_s
-      @highjack.original.call(logical_name)
+      @original.call(logical_name)
       return unless include?(logical_name)
       @zombified << logical_name
-      file = File.find(logical_name)
-      file.zombify(namespace) if file
-      self
+      zombify(find(logical_name))
+    end
+
+    # Find file by logical path
+    #
+    # @param [String] logical_name
+    #
+    # @return [File]
+    #
+    # @raise [LoadError]
+    #   otherwise
+    #
+    # @api private
+    #
+    def find(logical_name)
+      file_name = "#{logical_name}.rb"
+
+      load_path.each do |path|
+        path = pathname.new(path).join(file_name)
+        return path if path.file?
+      end
+
+      fail LoadError, "Cannot find file #{file_name.inspect} in load path"
+    end
+
+    # Zombify contents of file
+    #
+    # Probably the 2nd valid use of eval ever. (First one is inserting mutants!).
+    #
+    # @param [Pathname] source_path
+    #
+    # @return [undefined]
+    #
+    # @api private
+    #
+    # rubocop:disable Lint/Eval
+    #
+    def zombify(source_path)
+      kernel.eval(
+        Unparser.unparse(namespaced_node(source_path)),
+        TOPLEVEL_BINDING,
+        source_path.to_s
+      )
+    end
+
+    # Return namespaced root
+    #
+    # @param [Symbol] namespace
+    #
+    # @return [Parser::AST::Node]
+    #
+    # @api private
+    #
+    def namespaced_node(source_path)
+      s(:module, s(:const, nil, namespace), Parser::CurrentRuby.parse(source_path.read))
     end
 
   end # Zombifier

lib/mutant/zombifier/file.rb

@@ -1,100 +0,0 @@
-module Mutant
-  class Zombifier
-    # File containing source being zombified
-    class File
-      include Adamantium::Flat, Concord::Public.new(:path), AST::Sexp
-
-      # Zombify contents of file
-      #
-      # @return [self]
-      #
-      # @api private
-      #
-      # Probably one of the only valid uses of eval.
-      #
-      # rubocop:disable Lint/Eval
-      #
-      def zombify(namespace)
-        $stderr.puts("Zombifying #{path}")
-        eval(
-          Unparser.unparse(namespaced_node(namespace)),
-          TOPLEVEL_BINDING,
-          path.to_s
-        )
-        self
-      end
-
-      # Find file by logical path
-      #
-      # @param [String] logical_name
-      #
-      # @return [File]
-      #   if found
-      #
-      # @return [nil]
-      #   otherwise
-      #
-      # @api private
-      #
-      def self.find(logical_name)
-        file_name = expand_file_name(logical_name)
-
-        $LOAD_PATH.each do |path|
-          path = Pathname.new(path).join(file_name)
-          return new(path) if path.file?
-        end
-
-        $stderr.puts "Cannot find file #{file_name} in $LOAD_PATH"
-        nil
-      end
-
-      # Return expanded file name
-      #
-      # @param [String] logical_name
-      #
-      # @return [nil]
-      #   if no expansion is possible
-      #
-      # @return [String]
-      #
-      # @api private
-      #
-      def self.expand_file_name(logical_name)
-        case ::File.extname(logical_name)
-        when '.so'
-          return
-        when '.rb'
-          logical_name
-        else
-          "#{logical_name}.rb"
-        end
-      end
-      private_class_method :expand_file_name
-
-    private
-
-      # Return node
-      #
-      # @return [Parser::AST::Node]
-      #
-      # @api private
-      #
-      def node
-        Parser::CurrentRuby.parse(path.read, path.to_s)
-      end
-
-      # Return namespaced root
-      #
-      # @param [Symbol] namespace
-      #
-      # @return [Parser::AST::Node]
-      #
-      # @api private
-      #
-      def namespaced_node(namespace)
-        s(:module, s(:const, nil, namespace), node)
-      end
-
-    end # File
-  end # Zombifier
-end # Mutant

spec/integration/mutant/zombie_spec.rb

@@ -1,6 +0,0 @@
-RSpec.describe 'as a zombie', mutant: false do
-  specify 'it allows to create zombie from mutant' do
-    expect { Mutant.zombify }.to change { defined?(Zombie) }.from(nil).to('constant')
-    expect(Zombie.constants).to include(:Mutant)
-  end
-end

spec/spec_helper.rb

@@ -20,6 +20,7 @@ end
 
 require 'tempfile'
 require 'concord'
+require 'anima'
 require 'adamantium'
 require 'devtools/spec_helper'
 require 'unparser/cli'

spec/support/file_system.rb

@@ -0,0 +1,60 @@
+module MutantSpec
+  class FileState
+    DEFAULTS = IceNine.deep_freeze(
+      file:     false,
+      contents: nil,
+      requires: []
+    )
+
+    include Adamantium, Anima.new(*DEFAULTS.keys)
+
+    def self.new(attributes = DEFAULTS)
+      super(DEFAULTS.merge(attributes))
+    end
+
+    DOES_NOT_EXIST = new
+
+    alias_method :file?, :file
+  end # FileState
+
+  class FakePathname
+    include Adamantium, Concord.new(:file_system, :pathname)
+
+    def join(*arguments)
+      self.class.new(
+        file_system,
+        pathname.join(*arguments)
+      )
+    end
+
+    def read
+      state.contents
+    end
+
+    def to_s
+      pathname.to_s
+    end
+
+    def file?
+      state.file?
+    end
+
+  private
+
+    def state
+      file_system.state(pathname.to_s)
+    end
+  end # Pathname
+
+  class FileSystem
+    include Adamantium, Concord.new(:file_states)
+
+    def state(filename)
+      file_states.fetch(filename, FileState::DOES_NOT_EXIST)
+    end
+
+    def path(filename)
+      FakePathname.new(self, Pathname.new(filename))
+    end
+  end # FileSystem
+end # MutantSpec

spec/support/ruby_vm.rb

@@ -0,0 +1,82 @@
+module MutantSpec
+  # Not a real VM, just kidding. It connects the require / eval triggers
+  # require semantics Zombifier relies on in a way we can avoid having to
+  # mock around everyhwere to test every detail.
+  #
+  # rubocop:disable LineLength
+  class RubyVM
+    include Concord.new(:expected_events)
+
+    # An event being observed by the VM handlers
+    class EventObservation
+      include Concord::Public.new(:type, :payload)
+    end
+
+    # An event being expected, can advance the VM
+    class EventExpectation
+      include AbstractType, Anima.new(:expected_payload, :trigger_requires)
+
+      DEFAULTS = IceNine.deep_freeze(trigger_requires: [])
+
+      def initialize(attributes)
+        super(DEFAULTS.merge(attributes))
+      end
+
+      def handle(vm, observation)
+        unless match?(observation)
+          fail "Unexpected event observation: #{observation.inspect}, expected #{inspect}"
+        end
+
+        trigger_requires.each(&vm.method(:require))
+      end
+
+    private
+
+      abstract_method :advance_vm
+
+      def match?(observation)
+        observation.type.eql?(self.class) && observation.payload.eql?(expected_payload)
+      end
+
+      # Expectation and advance on require calls
+      class Require < self
+      end
+
+      # Expectation and advance on eval calls
+      class Eval < self
+      end
+    end
+
+    # A fake implementation of Kernel#require
+    def require(logical_name)
+      handle_event(EventObservation.new(EventExpectation::Require, logical_name: logical_name))
+      self
+    end
+
+    # A fake implementation of Kernel#eval
+    def eval(source, binding, location)
+      handle_event(
+        EventObservation.new(
+          EventExpectation::Eval,
+          binding:  binding,
+          source:   source,
+          source_location: location
+        )
+      )
+      self
+    end
+
+    # Test if VM events where fully processed
+    def done?
+      expected_events.empty?
+    end
+
+  private
+
+    def handle_event(observation)
+      fail "Unexpected event: #{observation.type} / #{observation.payload}" if expected_events.empty?
+
+      expected_events.slice!(0).handle(self, observation)
+    end
+  end
+end # MutantSpec

spec/unit/mutant/require_highjack_spec.rb

@@ -1,50 +1,47 @@
 RSpec.describe Mutant::RequireHighjack do
-  let(:object) { described_class.new(target, highjacked_calls.method(:push)) }
-
   let(:highjacked_calls) { [] }
   let(:require_calls)    { [] }
 
-  let(:target) do
+  let(:target_module) do
     acc = require_calls
     Module.new do
       define_method(:require, &acc.method(:<<))
+
       module_function :require
+      public :require
     end
   end
 
-  describe '#run' do
-    let(:block)        { -> {}                  }
+  def target_require(logical_name)
+    Object.new.extend(target_module).require(logical_name)
+  end
+
+  describe '.call' do
     let(:logical_name) { double('Logical Name') }
 
-    subject do
-      object.run(&block)
+    def apply
+      described_class.call(target_module, highjacked_calls.method(:<<))
     end
 
-    context 'require calls before run' do
-      it 'does not highjack anything' do
-        target.require(logical_name)
-        expect(require_calls).to eql([logical_name])
-        expect(highjacked_calls).to eql([])
-      end
+    it 'returns the original implementation from singleton' do
+      expect { apply.call(logical_name) }
+        .to change { require_calls }
+        .from([])
+        .to([logical_name])
     end
 
-    context 'require calls during run' do
-      let(:block) { -> { target.require(logical_name) } }
-
-      it 'does highjack the calls' do
-        expect { subject }.to change { highjacked_calls }.from([]).to([logical_name])
-        expect(require_calls).to eql([])
-      end
+    it 'does highjack target object #requires calls' do
+      apply
+      expect { target_require(logical_name) }
+        .to change { highjacked_calls }
+        .from([])
+        .to([logical_name])
     end
 
-    context 'require calls after run' do
-
-      it 'does not the calls anything' do
-        subject
-        target.require(logical_name)
-        expect(require_calls).to eql([logical_name])
-        expect(highjacked_calls).to eql([])
-      end
+    it 'does not call original require' do
+      apply
+      expect { target_require(logical_name) }
+        .not_to change { require_calls }.from([])
     end
   end
 end

spec/unit/mutant/zombifier_spec.rb

@@ -0,0 +1,120 @@
+RSpec.describe Mutant::Zombifier do
+  let(:root_require) { Pathname.new('project') }
+
+  let(:pathname) do
+    instance_double(::Pathname.singleton_class)
+  end
+
+  let(:require_highjack) do
+    lambda do |block|
+      original = ruby_vm.method(:require)
+      allow(ruby_vm).to receive(:require, &block)
+      original
+    end
+  end
+
+  let(:options) do
+    {
+      load_path:        %w[a b],
+      includes:         %w[project bar],
+      namespace:        :Zombie,
+      require_highjack: require_highjack,
+      root_require:     root_require,
+      pathname:         pathname,
+      kernel:           ruby_vm
+    }
+  end
+
+  let(:ruby_vm) do
+    MutantSpec::RubyVM.new(
+      [
+        MutantSpec::RubyVM::EventExpectation::Require.new(
+          expected_payload: {
+            logical_name: 'project'
+          }
+        ),
+        MutantSpec::RubyVM::EventExpectation::Eval.new(
+          expected_payload: {
+            binding:         TOPLEVEL_BINDING,
+            source:          "module Zombie\n  module Project\n  end\nend",
+            source_location: 'a/project.rb'
+          },
+          trigger_requires: %w[foo bar]
+        ),
+        MutantSpec::RubyVM::EventExpectation::Require.new(
+          expected_payload: {
+            logical_name: 'foo'
+          },
+          trigger_requires: %w[bar]
+        ),
+        MutantSpec::RubyVM::EventExpectation::Require.new(
+          expected_payload: {
+            logical_name: 'bar'
+          }
+        ),
+        MutantSpec::RubyVM::EventExpectation::Eval.new(
+          expected_payload: {
+            binding:         TOPLEVEL_BINDING,
+            source:          "module Zombie\n  module Bar\n  end\nend",
+            source_location: 'b/bar.rb'
+          },
+          trigger_requires: %w[]
+        ),
+        MutantSpec::RubyVM::EventExpectation::Require.new(
+          expected_payload: {
+            logical_name: 'bar'
+          }
+        )
+      ]
+    )
+  end
+
+  let(:require_effects) do
+    {
+      'project' => { requires: [] }
+    }
+  end
+
+  let(:file_entries) do
+    {
+      'a/project.rb' => { file: true, contents: 'module Project; end' },
+      'b/bar.rb' =>     { file: true, contents: 'module Bar; end'     }
+    }
+  end
+
+  let(:file_system) do
+    MutantSpec::FileSystem.new(
+      Hash[
+        file_entries.map { |key, attributes| [key, MutantSpec::FileState.new(attributes)] }
+      ]
+    )
+  end
+
+  describe '.call' do
+    def apply
+      described_class.call(options)
+    end
+
+    before do
+      allow(pathname).to receive(:new, &file_system.method(:path))
+    end
+
+    it 'returns self' do
+      expect(apply).to be(described_class)
+    end
+
+    it 'consumes walks the VM through expected steps' do
+      expect { apply }.to change { ruby_vm.done? }.from(false).to(true)
+    end
+
+    context 'when zombifier require fails' do
+      let(:file_entries) do
+        {}
+      end
+
+      it 'raises zombifier specific load error' do
+        expect { apply }.to raise_error(described_class::LoadError, 'Cannot find file "project.rb" in load path')
+      end
+    end
+  end
+end

spec/unit/mutant_spec.rb

@@ -13,15 +13,6 @@ RSpec.describe Mutant do
     it { should be(result) }
   end
 
-  describe '.zombify' do
-    subject { object.zombify }
-
-    it 'calls the zombifier' do
-      expect(Mutant::Zombifier).to receive(:run).with('mutant', :Zombie)
-      subject
-    end
-  end
-
   describe '.singleton_subclass_instance' do
     subject { object.singleton_subclass_instance(name, superclass, &block) }