Move complex matcher building out of CLI responsibilities

lib/mutant.rb

@@ -195,6 +195,7 @@ require 'mutant/subject/method'
 require 'mutant/subject/method/instance'
 require 'mutant/subject/method/singleton'
 require 'mutant/matcher'
+require 'mutant/matcher/builder'
 require 'mutant/matcher/chain'
 require 'mutant/matcher/method'
 require 'mutant/matcher/method/finder'
@@ -217,7 +218,6 @@ require 'mutant/runner/subject'
 require 'mutant/runner/mutation'
 require 'mutant/runner/killer'
 require 'mutant/cli'
-require 'mutant/cli/builder'
 require 'mutant/color'
 require 'mutant/diff'
 require 'mutant/reporter'

lib/mutant/cli.rb

@@ -39,7 +39,7 @@ module Mutant
     # @api private
     #
     def initialize(arguments = [])
-      @builder = Builder.new
+      @builder = Matcher::Builder.new
       @debug = @fail_fast = @zombie = false
       @expected_coverage = 100.0
       @strategy = Strategy::Null.new
@@ -101,13 +101,14 @@ module Mutant
 
     # Parse matchers
     #
-    # @param [Enumerable<String>] patterns
+    # @param [Array<String>] patterns
     #
     # @return [undefined]
     #
     # @api private
     #
     def parse_matchers(patterns)
+      raise Error, 'No patterns given' if patterns.empty?
       patterns.each do |pattern|
         expression = Expression.parse(pattern)
         unless expression

lib/mutant/matcher/builder.rb

@@ -1,6 +1,6 @@
 module Mutant
-  class CLI
-    # Builder for configuration components
+  class Matcher
+    # Builder for complex matchers
     class Builder
       include NodeHelpers
 
@@ -63,7 +63,7 @@ module Mutant
       #
       def matcher
         if @matchers.empty?
-          raise(Error, 'No patterns given')
+          return Matcher::Null.new
         end
 
         matcher = Matcher::Chain.build(@matchers)
@@ -135,5 +135,5 @@ module Mutant
       end
 
     end # Builder
-  end # CLI
+  end # Matcher
 end # Mutant