Add Mutant::LineTrace

* Depends on `TracePoint` thus removes 1.9 compatiblity.
  I do not expect someone is harmed by this.

.travis.yml

@@ -3,7 +3,6 @@ script: "bundle exec rake ci"
 env:
   - TRAVIS=true
 rvm:
-  - 1.9.3
   - 2.0.0
   - 2.1.4
   - rbx-2

config/flay.yml

@@ -1,3 +1,3 @@
 ---
 threshold: 18
-total_score: 1148
+total_score: 1161

config/reek.yml

@@ -37,6 +37,7 @@ FeatureEnvy:
   - Mutant::Runner::Master#stop_worker
   - Mutant::Runner::Worker#run_mutation
   - Mutant::Runner::Worker#handle
+  - Mutant::Subject#source_lines
 IrresponsibleModule:
   enabled: true
   exclude: []

lib/mutant.rb

@@ -211,6 +211,7 @@ require 'mutant/reporter/cli'
 require 'mutant/reporter/cli/printer'
 require 'mutant/reporter/cli/tput'
 require 'mutant/reporter/cli/format'
+require 'mutant/line_trace'
 require 'mutant/zombifier'
 require 'mutant/zombifier/file'
 

lib/mutant/line_trace.rb

@@ -0,0 +1,34 @@
+module Mutant
+  # Line tracer
+  class LineTrace
+    include Adamantium::Flat, Concord.new(:contents)
+
+    private_class_method :new
+
+    # Test if trace coveres file at lineno
+    #
+    # @param [String] file
+    # @param [Fixnum] lineno
+    #
+    # @return [Boolean]
+    #
+    def cover?(file, lineno)
+      contents.fetch(file) { return false }.include?(lineno)
+    end
+
+    # Run block
+    #
+    # @return [Traces]
+    #
+    # @api private
+    #
+    def self.call(&block)
+      traces = Hash.new { |hash, file| hash[file] = Set.new }
+      TracePoint.trace(:return, :line) do |point|
+        traces[point.path] << point.lineno
+      end.tap(&block).disable
+      new(IceNine.deep_freeze(traces))
+    end
+
+  end # LineTrace
+end # Mutant

mutant.gemspec

@@ -21,7 +21,7 @@ Gem::Specification.new do |gem|
   gem.extra_rdoc_files = %w[TODO LICENSE]
   gem.executables      = %w[mutant]
 
-  gem.required_ruby_version = '>= 1.9.3'
+  gem.required_ruby_version = '>= 2.0.0'
 
   gem.add_runtime_dependency('parser',        '~> 2.2.pre.7')
   gem.add_runtime_dependency('ast',           '~> 2.0')

spec/unit/mutant/line_trace_spec.rb

@@ -0,0 +1,38 @@
+RSpec.describe Mutant::LineTrace do
+  let(:object) { described_class }
+
+  test_a_line = __LINE__ + 2
+  def test_a
+    test_b
+  end
+
+  test_b_line = __LINE__ + 2
+  def test_b
+  end
+
+  test_c_line = __LINE__ + 2
+  def test_c
+  end
+
+  shared_examples_for 'line trace' do
+    it 'returns correct trace results' do
+      expect(subject.cover?(__FILE__, test_a_line)).to be(true)
+      expect(subject.cover?(__FILE__, test_b_line)).to be(true)
+      expect(subject.cover?(__FILE__, test_c_line)).to be(false)
+      expect(subject.cover?(__FILE__, __LINE__)).to be(false)
+      expect(subject.cover?('/dev/null', test_a_line)).to be(false)
+    end
+  end
+
+  describe '.cover?' do
+    subject { object.call { test_a } }
+
+    include_examples 'line trace'
+  end
+
+  describe '.call' do
+    subject { object.call { test_a } }
+
+    include_examples 'line trace'
+  end
+end