From caf6c368d0ab423c6b653b1364fff42cccb21408 Mon Sep 17 00:00:00 2001
From: Markus Schirp <mbj@schirp-dso.com>
Date: Sat, 10 May 2014 14:32:18 +0000
Subject: [PATCH] Remove indeterministic mutations

A mutation test that passes/fails on code today should also pass/fail on
the same code tomorrow.

* Closes #173
* Closes #127
* Closes #27
---
 config/flay.yml                               |  2 +-
 lib/mutant.rb                                 |  2 -
 lib/mutant/mutator/node/literal/fixnum.rb     |  1 -
 lib/mutant/mutator/node/literal/float.rb      |  1 -
 lib/mutant/mutator/node/literal/string.rb     |  1 -
 lib/mutant/mutator/node/literal/symbol.rb     |  8 +++-
 .../node/named_value/variable_assignment.rb   | 11 ++++--
 lib/mutant/mutator/util/symbol.rb             |  4 +-
 lib/mutant/random.rb                          | 38 -------------------
 .../unit/mutant/mutator/node/and_asgn_spec.rb | 10 +----
 spec/unit/mutant/mutator/node/block_spec.rb   | 24 +++---------
 spec/unit/mutant/mutator/node/case_spec.rb    | 26 +++++--------
 spec/unit/mutant/mutator/node/define_spec.rb  | 22 +++--------
 spec/unit/mutant/mutator/node/dstr_spec.rb    |  6 ---
 spec/unit/mutant/mutator/node/dsym_spec.rb    |  5 ---
 spec/unit/mutant/mutator/node/if_spec.rb      | 30 +++++++--------
 .../mutator/node/literal/fixnum_spec.rb       |  8 +---
 .../mutant/mutator/node/literal/float_spec.rb |  9 -----
 .../mutant/mutator/node/literal/range_spec.rb | 10 -----
 .../mutator/node/literal/string_spec.rb       |  6 +--
 .../mutator/node/literal/symbol_spec.rb       |  6 +--
 .../mutator/node/named_value/access_spec.rb   | 11 ++----
 .../named_value/constant_assignment_spec.rb   |  6 +--
 .../named_value/variable_assignment_spec.rb   | 12 ++----
 .../unit/mutant/mutator/node/op_assgn_spec.rb |  7 ----
 spec/unit/mutant/mutator/node/or_asgn_spec.rb | 10 +----
 spec/unit/mutant/mutator/node/rescue_spec.rb  |  4 --
 27 files changed, 66 insertions(+), 214 deletions(-)
 delete mode 100644 lib/mutant/random.rb

diff --git a/config/flay.yml b/config/flay.yml
index 5436ecc7..cacdaef7 100644
--- a/config/flay.yml
+++ b/config/flay.yml
@@ -1,3 +1,3 @@
 ---
 threshold: 18
-total_score: 829
+total_score: 839
diff --git a/lib/mutant.rb b/lib/mutant.rb
index 4a0e76ec..118a5c9f 100644
--- a/lib/mutant.rb
+++ b/lib/mutant.rb
@@ -5,7 +5,6 @@ require 'set'
 require 'adamantium'
 require 'ice_nine'
 require 'abstract_type'
-require 'securerandom'
 require 'equalizer'
 require 'digest/sha1'
 require 'inflecto'
@@ -83,7 +82,6 @@ require 'mutant/node_helpers'
 require 'mutant/warning_filter'
 require 'mutant/warning_expectation'
 require 'mutant/constants'
-require 'mutant/random'
 require 'mutant/walker'
 require 'mutant/require_highjack'
 require 'mutant/mutator'
diff --git a/lib/mutant/mutator/node/literal/fixnum.rb b/lib/mutant/mutator/node/literal/fixnum.rb
index 86436277..8b2bebda 100644
--- a/lib/mutant/mutator/node/literal/fixnum.rb
+++ b/lib/mutant/mutator/node/literal/fixnum.rb
@@ -20,7 +20,6 @@ module Mutant
           def dispatch
             emit_nil
             emit_values(values)
-            emit_new { new_self(Random.fixnum) }
           end
 
           # Return values to mutate against
diff --git a/lib/mutant/mutator/node/literal/float.rb b/lib/mutant/mutator/node/literal/float.rb
index af3e5f89..cfffb7a1 100644
--- a/lib/mutant/mutator/node/literal/float.rb
+++ b/lib/mutant/mutator/node/literal/float.rb
@@ -21,7 +21,6 @@ module Mutant
             emit_nil
             emit_values(values)
             emit_special_cases
-            emit_new { new_self(Random.float) }
           end
 
           SPECIAL = [
diff --git a/lib/mutant/mutator/node/literal/string.rb b/lib/mutant/mutator/node/literal/string.rb
index 6abd8cf2..fe1646e8 100644
--- a/lib/mutant/mutator/node/literal/string.rb
+++ b/lib/mutant/mutator/node/literal/string.rb
@@ -19,7 +19,6 @@ module Mutant
           #
           def dispatch
             emit_nil
-            emit_new { new_self(Random.hex_string) }
           end
 
         end # String
diff --git a/lib/mutant/mutator/node/literal/symbol.rb b/lib/mutant/mutator/node/literal/symbol.rb
index ad1f4f62..2b6a2cf4 100644
--- a/lib/mutant/mutator/node/literal/symbol.rb
+++ b/lib/mutant/mutator/node/literal/symbol.rb
@@ -9,7 +9,9 @@ module Mutant
 
           handle(:sym)
 
-          PREFIX = 's'
+          children :value
+
+          PREFIX = '__mutant__'.freeze
 
         private
 
@@ -21,7 +23,9 @@ module Mutant
           #
           def dispatch
             emit_nil
-            emit_new { new_self((PREFIX + Random.hex_string).to_sym) }
+            Mutator::Util::Symbol.each(value, self) do |value|
+              emit_self(value)
+            end
           end
 
         end # Symbol
diff --git a/lib/mutant/mutator/node/named_value/variable_assignment.rb b/lib/mutant/mutator/node/named_value/variable_assignment.rb
index 3855e99d..9295c6fc 100644
--- a/lib/mutant/mutator/node/named_value/variable_assignment.rb
+++ b/lib/mutant/mutator/node/named_value/variable_assignment.rb
@@ -10,11 +10,15 @@ module Mutant
 
           children :name, :value
 
-          MAP = IceNine.deep_freeze(
+          map = {
             gvasgn: '$',
             cvasgn: '@@',
             ivasgn: '@',
             lvasgn: ''
+          }
+
+          MAP = IceNine.deep_freeze(
+            Hash[map.map { |type, prefix| [type, [prefix, /^#{Regexp.escape(prefix)}/]] }]
           )
 
           handle(*MAP.keys)
@@ -40,8 +44,9 @@ module Mutant
           # @api private
           #
           def mutate_name
-            prefix = MAP.fetch(node.type)
-            Mutator::Util::Symbol.each(name, self) do |name|
+            prefix, regexp = MAP.fetch(node.type)
+            stripped = name.to_s.sub(regexp, EMPTY_STRING)
+            Mutator::Util::Symbol.each(stripped, self) do |name|
               emit_name(:"#{prefix}#{name}")
             end
           end
diff --git a/lib/mutant/mutator/util/symbol.rb b/lib/mutant/mutator/util/symbol.rb
index 8c943131..dae441c0 100644
--- a/lib/mutant/mutator/util/symbol.rb
+++ b/lib/mutant/mutator/util/symbol.rb
@@ -9,6 +9,8 @@ module Mutant
 
         handle(::Symbol)
 
+        POSTFIX = '__mutant__'.freeze
+
       private
 
         # Emit mutations
@@ -18,7 +20,7 @@ module Mutant
         # @api private
         #
         def dispatch
-          emit_new { :"s#{Random.hex_string}" }
+          emit((input.to_s + POSTFIX).to_sym)
         end
 
       end # Symbol
diff --git a/lib/mutant/random.rb b/lib/mutant/random.rb
deleted file mode 100644
index 227277ae..00000000
--- a/lib/mutant/random.rb
+++ /dev/null
@@ -1,38 +0,0 @@
-# encoding: utf-8
-
-module Mutant
-  # Module for generating random values
-  module Random
-
-    # Return random hex string
-    #
-    # @return [String]
-    #
-    # @api private
-    #
-    def self.hex_string
-      SecureRandom.hex(10)
-    end
-
-    # Return random fixnum
-    #
-    # @return [Fixnum]
-    #
-    # @api private
-    #
-    def self.fixnum
-      ::Random.rand(1000)
-    end
-
-    # Return random float
-    #
-    # @return [Float]
-    #
-    # @api private
-    #
-    def self.float
-      ::Random.rand
-    end
-
-  end # Random
-end # Mutant
diff --git a/spec/unit/mutant/mutator/node/and_asgn_spec.rb b/spec/unit/mutant/mutator/node/and_asgn_spec.rb
index 54adc364..9a1f0ddb 100644
--- a/spec/unit/mutant/mutator/node/and_asgn_spec.rb
+++ b/spec/unit/mutant/mutator/node/and_asgn_spec.rb
@@ -3,25 +3,17 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::OpAsgn, 'and_asgn' do
-  let(:random_fixnum) { 5        }
-  let(:random_string) { 'random' }
-
   let(:source)  { 'a &&= 1' }
 
   let(:mutations) do
     mutations = []
-    mutations << 'srandom &&= 1'
+    mutations << 'a__mutant__ &&= 1'
     mutations << 'a &&= nil'
     mutations << 'a &&= 0'
     mutations << 'a &&= -1'
     mutations << 'a &&= 2'
-    mutations << 'a &&= 5'
     mutations << 'nil'
   end
 
-  before do
-    Mutant::Random.stub(fixnum: random_fixnum, hex_string: random_string)
-  end
-
   it_should_behave_like 'a mutator'
 end
diff --git a/spec/unit/mutant/mutator/node/block_spec.rb b/spec/unit/mutant/mutator/node/block_spec.rb
index 5af30944..9b4655af 100644
--- a/spec/unit/mutant/mutator/node/block_spec.rb
+++ b/spec/unit/mutant/mutator/node/block_spec.rb
@@ -25,16 +25,12 @@ describe Mutant::Mutator, 'block' do
 
     let(:source) { 'foo { |a, b| }' }
 
-    before do
-      Mutant::Random.stub(hex_string: 'random')
-    end
-
     let(:mutations) do
       mutations = []
       mutations << 'foo'
       mutations << 'foo { |a, b| raise }'
-      mutations << 'foo { |a, srandom| }'
-      mutations << 'foo { |srandom, b| }'
+      mutations << 'foo { |a, b__mutant__| }'
+      mutations << 'foo { |a__mutant__, b| }'
       mutations << 'foo { |a| }'
       mutations << 'foo { |b| }'
       mutations << 'foo { || }'
@@ -46,10 +42,6 @@ describe Mutant::Mutator, 'block' do
 
   context 'with block pattern args' do
 
-    before do
-      Mutant::Random.stub(hex_string: 'random')
-    end
-
     let(:source) { 'foo { |(a, b), c| }' }
 
     let(:mutations) do
@@ -61,9 +53,9 @@ describe Mutant::Mutator, 'block' do
       mutations << 'foo { |(b), c| }'
       mutations << 'foo { |(a, b)| }'
       mutations << 'foo { |c| }'
-      mutations << 'foo { |(srandom, b), c| }'
-      mutations << 'foo { |(a, srandom), c| }'
-      mutations << 'foo { |(a, b), srandom| }'
+      mutations << 'foo { |(a__mutant__, b), c| }'
+      mutations << 'foo { |(a, b__mutant__), c| }'
+      mutations << 'foo { |(a, b), c__mutant__| }'
       mutations << 'foo'
       mutations << 'nil'
     end
@@ -73,10 +65,6 @@ describe Mutant::Mutator, 'block' do
 
   context 'with mini block pattern arg' do
 
-    before do
-      Mutant::Random.stub(hex_string: 'random')
-    end
-
     let(:source) { 'foo { |(a)| }' }
 
     let(:mutations) do
@@ -84,7 +72,7 @@ describe Mutant::Mutator, 'block' do
       mutations << 'foo { || }'
       mutations << 'foo { |a| }'
       mutations << 'foo { |(a)| raise }'
-      mutations << 'foo { |(srandom)| }'
+      mutations << 'foo { |(a__mutant__)| }'
       mutations << 'foo'
       mutations << 'nil'
     end
diff --git a/spec/unit/mutant/mutator/node/case_spec.rb b/spec/unit/mutant/mutator/node/case_spec.rb
index f91369ed..d9fb6b64 100644
--- a/spec/unit/mutant/mutator/node/case_spec.rb
+++ b/spec/unit/mutant/mutator/node/case_spec.rb
@@ -3,12 +3,6 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Case do
-  let(:random_string) { 'random' }
-
-  before do
-    Mutant::Random.stub(hex_string: random_string)
-  end
-
   context 'without condition' do
     let(:source) do
       <<-RUBY
@@ -97,7 +91,7 @@ describe Mutant::Mutator::Node::Case do
         end
       RUBY
       mutations << <<-RUBY
-        case :srandom
+        case :condition__mutant__
         when :foo
         when :bar, :baz
           :barbaz
@@ -121,7 +115,7 @@ describe Mutant::Mutator::Node::Case do
         case :condition
         when :foo
         when :bar, :baz
-          :srandom
+          :barbaz__mutant__
         else
           :else
         end
@@ -141,7 +135,7 @@ describe Mutant::Mutator::Node::Case do
         when :bar, :baz
           :barbaz
         else
-          :srandom
+          :else__mutant__
         end
       RUBY
       mutations << <<-RUBY
@@ -157,7 +151,7 @@ describe Mutant::Mutator::Node::Case do
       # Mutations of when conditions
       mutations << <<-RUBY
         case :condition
-        when :srandom
+        when :foo__mutant__
         when :bar, :baz
           :barbaz
         else
@@ -176,7 +170,7 @@ describe Mutant::Mutator::Node::Case do
       mutations << <<-RUBY
         case :condition
         when :foo
-        when :srandom, :baz
+        when :bar__mutant__, :baz
           :barbaz
         else
           :else
@@ -203,7 +197,7 @@ describe Mutant::Mutator::Node::Case do
       mutations << <<-RUBY
         case :condition
         when :foo
-        when :bar, :srandom
+        when :bar, :baz__mutant__
           :barbaz
         else
           :else
@@ -267,7 +261,7 @@ describe Mutant::Mutator::Node::Case do
         end
       RUBY
       mutations << <<-RUBY
-        case :srandom
+        case :condition__mutant__
         when :foo
           :foo
         else
@@ -287,7 +281,7 @@ describe Mutant::Mutator::Node::Case do
       mutations << <<-RUBY
         case :condition
         when :foo
-          :srandom
+          :foo__mutant__
         else
           :else
         end
@@ -297,7 +291,7 @@ describe Mutant::Mutator::Node::Case do
         when :foo
           :foo
         else
-          :srandom
+          :else__mutant__
         end
       RUBY
       mutations << <<-RUBY
@@ -312,7 +306,7 @@ describe Mutant::Mutator::Node::Case do
       # Mutations of when conditions
       mutations << <<-RUBY
         case :condition
-        when :srandom
+        when :foo__mutant__
           :foo
         else
           :else
diff --git a/spec/unit/mutant/mutator/node/define_spec.rb b/spec/unit/mutant/mutator/node/define_spec.rb
index 4fcf53e7..41911041 100644
--- a/spec/unit/mutant/mutator/node/define_spec.rb
+++ b/spec/unit/mutant/mutator/node/define_spec.rb
@@ -55,10 +55,6 @@ describe Mutant::Mutator, 'def' do
   context 'with arguments' do
     let(:source) { 'def foo(a, b); end' }
 
-    before do
-      Mutant::Random.stub(hex_string: 'random')
-    end
-
     let(:mutations) do
       mutations = []
 
@@ -70,8 +66,8 @@ describe Mutant::Mutator, 'def' do
       mutations << 'def foo; end'
 
       # Rename each argument
-      mutations << 'def foo(srandom, b); end'
-      mutations << 'def foo(a, srandom); end'
+      mutations << 'def foo(a__mutant__, b); end'
+      mutations << 'def foo(a, b__mutant__); end'
 
       # Mutation of body
       mutations << 'def foo(a, b); raise; end'
@@ -110,17 +106,13 @@ describe Mutant::Mutator, 'def' do
   context 'default argument' do
     let(:source) { 'def foo(a = true); end' }
 
-    before do
-      Mutant::Random.stub(hex_string: 'random')
-    end
-
     let(:mutations) do
       mutations = []
       mutations << 'def foo(a); end'
       mutations << 'def foo(); end'
       mutations << 'def foo(a = false); end'
       mutations << 'def foo(a = nil); end'
-      mutations << 'def foo(srandom = true); end'
+      mutations << 'def foo(a__mutant__ = true); end'
       mutations << 'def foo(a = true); raise; end'
     end
 
@@ -154,10 +146,6 @@ describe Mutant::Mutator, 'def' do
 
   context 'define on singleton with argument' do
 
-    before do
-      Mutant::Random.stub(hex_string: 'random')
-    end
-
     let(:source) { 'def self.foo(a, b); end' }
 
     let(:mutations) do
@@ -171,8 +159,8 @@ describe Mutant::Mutator, 'def' do
       mutations << 'def self.foo; end'
 
       # Rename each argument
-      mutations << 'def self.foo(srandom, b); end'
-      mutations << 'def self.foo(a, srandom); end'
+      mutations << 'def self.foo(a__mutant__, b); end'
+      mutations << 'def self.foo(a, b__mutant__); end'
 
       # Mutation of body
       mutations << 'def self.foo(a, b); raise; end'
diff --git a/spec/unit/mutant/mutator/node/dstr_spec.rb b/spec/unit/mutant/mutator/node/dstr_spec.rb
index b47665c2..d81bf6ae 100644
--- a/spec/unit/mutant/mutator/node/dstr_spec.rb
+++ b/spec/unit/mutant/mutator/node/dstr_spec.rb
@@ -3,17 +3,11 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Dstr, 'dstr' do
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
-
   let(:source)  { '"foo#{bar}baz"' }
 
   let(:mutations) do
     mutations = []
-    mutations << '"random#{bar}baz"'
     mutations << '"#{nil}#{bar}baz"'
-    mutations << '"foo#{bar}random"'
     mutations << '"foo#{bar}#{nil}"'
     mutations << '"foo#{nil}baz"'
     mutations << 'nil'
diff --git a/spec/unit/mutant/mutator/node/dsym_spec.rb b/spec/unit/mutant/mutator/node/dsym_spec.rb
index 6b771f6a..7bb30ea8 100644
--- a/spec/unit/mutant/mutator/node/dsym_spec.rb
+++ b/spec/unit/mutant/mutator/node/dsym_spec.rb
@@ -3,17 +3,12 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Dsym, 'dsym' do
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
 
   let(:source)  { ':"foo#{bar}baz"' }
 
   let(:mutations) do
     mutations = []
-    mutations << ':"random#{bar}baz"'
     mutations << ':"#{nil}#{bar}baz"'
-    mutations << ':"foo#{bar}random"'
     mutations << ':"foo#{bar}#{nil}"'
     mutations << ':"foo#{nil}baz"'
     mutations << 'nil'
diff --git a/spec/unit/mutant/mutator/node/if_spec.rb b/spec/unit/mutant/mutator/node/if_spec.rb
index 8a466af0..c51d6487 100644
--- a/spec/unit/mutant/mutator/node/if_spec.rb
+++ b/spec/unit/mutant/mutator/node/if_spec.rb
@@ -3,10 +3,6 @@
 require 'spec_helper'
 
 describe Mutant::Mutator, 'if' do
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
-
   context 'with if and else branches' do
     let(:source) { 'if :condition; true; else false; end' }
 
@@ -14,11 +10,11 @@ describe Mutant::Mutator, 'if' do
       mutants = []
 
       # mutations of condition
-      mutants << 'if :srandom;    true; else false; end'
-      mutants << 'if !:condition; true; else false; end'
-      mutants << 'if nil;         true; else false; end'
-      mutants << 'if true;        true; else false; end'
-      mutants << 'if false;       true; else false; end'
+      mutants << 'if :condition__mutant__; true; else false; end'
+      mutants << 'if !:condition;          true; else false; end'
+      mutants << 'if nil;                  true; else false; end'
+      mutants << 'if true;                 true; else false; end'
+      mutants << 'if false;                true; else false; end'
 
       # Deleted else branch
       mutants << 'if :condition; true end'
@@ -65,14 +61,14 @@ describe Mutant::Mutator, 'if' do
 
     let(:mutations) do
       mutants = []
-      mutants << 'unless !:condition; true;  end'
-      mutants << 'unless :srandom;    true;  end'
-      mutants << 'unless nil;         true;  end'
-      mutants << 'unless :condition;  false; end'
-      mutants << 'unless :condition;  nil;   end'
-      mutants << 'unless true;        true;  end'
-      mutants << 'unless false;       true;  end'
-      mutants << 'if     :condition;  true;  end'
+      mutants << 'unless !:condition;          true;  end'
+      mutants << 'unless :condition__mutant__; true;  end'
+      mutants << 'unless nil;                  true;  end'
+      mutants << 'unless :condition;           false; end'
+      mutants << 'unless :condition;           nil;   end'
+      mutants << 'unless true;                 true;  end'
+      mutants << 'unless false;                true;  end'
+      mutants << 'if     :condition;           true;  end'
       mutants << 'nil'
     end
 
diff --git a/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb b/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb
index c0d134e8..bb199072 100644
--- a/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/fixnum_spec.rb
@@ -3,16 +3,10 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'fixnum' do
-  let(:random_fixnum) { 5 }
-
   let(:source) { '10' }
 
   let(:mutations) do
-    %W(nil 0 1 #{random_fixnum} -10 9 11)
-  end
-
-  before do
-    Mutant::Random.stub(fixnum: random_fixnum)
+    %W(nil 0 1 -10 9 11)
   end
 
   it_should_behave_like 'a mutator'
diff --git a/spec/unit/mutant/mutator/node/literal/float_spec.rb b/spec/unit/mutant/mutator/node/literal/float_spec.rb
index 0b6c9259..871edb33 100644
--- a/spec/unit/mutant/mutator/node/literal/float_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/float_spec.rb
@@ -4,12 +4,6 @@ require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'float' do
 
-  before do
-    Mutant::Random.stub(float: random_float)
-  end
-
-  let(:random_float) { 7.123 }
-
   context 'positive number' do
     let(:source) { '10.0' }
 
@@ -18,7 +12,6 @@ describe Mutant::Mutator::Node::Literal, 'float' do
       mutations << 'nil'
       mutations << '0.0'
       mutations << '1.0'
-      mutations << random_float.to_s
       mutations << '(0.0 / 0.0)'
       mutations << '(1.0 / 0.0)'
       mutations << '(-1.0 / 0.0)'
@@ -35,7 +28,6 @@ describe Mutant::Mutator::Node::Literal, 'float' do
       mutations = []
       mutations << 'nil'
       mutations << '1.0'
-      mutations << random_float.to_s
       mutations << '(0.0 / 0.0)'
       mutations << '(1.0 / 0.0)'
       mutations << '(-1.0 / 0.0)'
@@ -51,7 +43,6 @@ describe Mutant::Mutator::Node::Literal, 'float' do
       mutations = []
       mutations << 'nil'
       mutations << '1.0'
-      mutations << random_float.to_s
       mutations << '(0.0 / 0.0)'
       mutations << '(1.0 / 0.0)'
       mutations << '(-1.0 / 0.0)'
diff --git a/spec/unit/mutant/mutator/node/literal/range_spec.rb b/spec/unit/mutant/mutator/node/literal/range_spec.rb
index 33f8c1df..1323f322 100644
--- a/spec/unit/mutant/mutator/node/literal/range_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/range_spec.rb
@@ -4,12 +4,6 @@ require 'spec_helper'
 
 describe Mutant::Mutator::Node::Literal, 'range' do
 
-  before :each do
-    Mutant::Random.stub(fixnum: random_fixnum)
-  end
-
-  let(:random_fixnum) { 5 }
-
   context 'inclusive range literal' do
     let(:source) { '1..100' }
 
@@ -21,7 +15,6 @@ describe Mutant::Mutator::Node::Literal, 'range' do
       mutations << '1..(1.0 / 0.0)'
       mutations << '1..(0.0 / 0.0)'
       mutations << '-1..100'
-      mutations << '5..100'
       mutations << '0..100'
       mutations << '2..100'
       mutations << 'nil..100'
@@ -31,7 +24,6 @@ describe Mutant::Mutator::Node::Literal, 'range' do
       mutations << '1..99'
       mutations << '1..101'
       mutations << '1..-100'
-      mutations << '1..5'
     end
 
     it_should_behave_like 'a mutator'
@@ -48,7 +40,6 @@ describe Mutant::Mutator::Node::Literal, 'range' do
       mutations << '1...(1.0 / 0.0)'
       mutations << '1...(0.0 / 0.0)'
       mutations << '-1...100'
-      mutations << '5...100'
       mutations << '0...100'
       mutations << '2...100'
       mutations << 'nil...100'
@@ -58,7 +49,6 @@ describe Mutant::Mutator::Node::Literal, 'range' do
       mutations << '1...99'
       mutations << '1...101'
       mutations << '1...-100'
-      mutations << '1...5'
     end
 
     it_should_behave_like 'a mutator'
diff --git a/spec/unit/mutant/mutator/node/literal/string_spec.rb b/spec/unit/mutant/mutator/node/literal/string_spec.rb
index e11cb780..51ffd2fa 100644
--- a/spec/unit/mutant/mutator/node/literal/string_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/string_spec.rb
@@ -8,11 +8,7 @@ describe Mutant::Mutator::Node::Literal, 'string' do
   let(:source) { '"foo"' }
 
   let(:mutations) do
-    %W(nil "#{random_string}")
-  end
-
-  before do
-    Mutant::Random.stub(hex_string: random_string)
+    %W(nil)
   end
 
   it_should_behave_like 'a mutator'
diff --git a/spec/unit/mutant/mutator/node/literal/symbol_spec.rb b/spec/unit/mutant/mutator/node/literal/symbol_spec.rb
index f4ee7874..31ced8fe 100644
--- a/spec/unit/mutant/mutator/node/literal/symbol_spec.rb
+++ b/spec/unit/mutant/mutator/node/literal/symbol_spec.rb
@@ -8,11 +8,7 @@ describe Mutant::Mutator::Node::Literal, 'symbol' do
   let(:source) { ':foo' }
 
   let(:mutations) do
-    %w(nil) << ":s#{random_string}"
-  end
-
-  before do
-    Mutant::Random.stub(hex_string: random_string)
+    %w(nil) << ':foo__mutant__'
   end
 
   it_should_behave_like 'a mutator'
diff --git a/spec/unit/mutant/mutator/node/named_value/access_spec.rb b/spec/unit/mutant/mutator/node/named_value/access_spec.rb
index efc0ece0..91f739f3 100644
--- a/spec/unit/mutant/mutator/node/named_value/access_spec.rb
+++ b/spec/unit/mutant/mutator/node/named_value/access_spec.rb
@@ -3,9 +3,6 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::Access, 'mutations' do
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
 
   context 'global variable' do
     let(:source) { '$a = nil; $a' }
@@ -15,7 +12,7 @@ describe Mutant::Mutator::Node::NamedValue::Access, 'mutations' do
       mutants << '$a = nil; nil'
       mutants << '$a = nil'
       mutants << '$a'
-      mutants << '$srandom = nil; $a'
+      mutants << '$a__mutant__ = nil; $a'
       mutants << 'nil; $a'
     end
 
@@ -30,7 +27,7 @@ describe Mutant::Mutator::Node::NamedValue::Access, 'mutations' do
       mutants << '@@a = nil; nil'
       mutants << '@@a = nil'
       mutants << '@@a'
-      mutants << '@@srandom = nil; @@a'
+      mutants << '@@a__mutant__ = nil; @@a'
       mutants << 'nil; @@a'
     end
   end
@@ -43,7 +40,7 @@ describe Mutant::Mutator::Node::NamedValue::Access, 'mutations' do
       mutants << '@a = nil; nil'
       mutants << '@a = nil'
       mutants << '@a'
-      mutants << '@srandom = nil; @a'
+      mutants << '@a__mutant__ = nil; @a'
       mutants << 'nil; @a'
     end
 
@@ -60,7 +57,7 @@ describe Mutant::Mutator::Node::NamedValue::Access, 'mutations' do
       # TODO: fix invalid AST
       #   These ASTs are not valid and should NOT be emitted
       #   Mutations of lvarasgn need to be special cased to avoid this.
-      mutants << s(:begin, s(:lvasgn, :srandom, s(:nil)), s(:lvar, :a))
+      mutants << s(:begin, s(:lvasgn, :a__mutant__, s(:nil)), s(:lvar, :a))
       mutants << s(:begin, s(:nil), s(:lvar, :a))
       mutants << s(:lvar, :a)
     end
diff --git a/spec/unit/mutant/mutator/node/named_value/constant_assignment_spec.rb b/spec/unit/mutant/mutator/node/named_value/constant_assignment_spec.rb
index 97aecc04..32d45498 100644
--- a/spec/unit/mutant/mutator/node/named_value/constant_assignment_spec.rb
+++ b/spec/unit/mutant/mutator/node/named_value/constant_assignment_spec.rb
@@ -3,15 +3,11 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
-
   let(:source) { 'A = true' }
 
   let(:mutations) do
     mutations = []
-    mutations << 'SRANDOM = true'
+    mutations << 'A__MUTANT__ = true'
     mutations << 'A = false'
     mutations << 'A = nil'
   end
diff --git a/spec/unit/mutant/mutator/node/named_value/variable_assignment_spec.rb b/spec/unit/mutant/mutator/node/named_value/variable_assignment_spec.rb
index 044b989a..535a3575 100644
--- a/spec/unit/mutant/mutator/node/named_value/variable_assignment_spec.rb
+++ b/spec/unit/mutant/mutator/node/named_value/variable_assignment_spec.rb
@@ -3,16 +3,12 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
-
   context 'global variable' do
     let(:source) { '$a = true' }
 
     let(:mutations) do
       mutations = []
-      mutations << '$srandom = true'
+      mutations << '$a__mutant__ = true'
       mutations << '$a = false'
       mutations << '$a = nil'
       mutations << 'nil'
@@ -26,7 +22,7 @@ describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
 
     let(:mutations) do
       mutations = []
-      mutations << '@@srandom = true'
+      mutations << '@@a__mutant__ = true'
       mutations << '@@a = false'
       mutations << '@@a = nil'
       mutations << 'nil'
@@ -40,7 +36,7 @@ describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
 
     let(:mutations) do
       mutations = []
-      mutations << '@srandom = true'
+      mutations << '@a__mutant__ = true'
       mutations << '@a = false'
       mutations << '@a = nil'
       mutations << 'nil'
@@ -54,7 +50,7 @@ describe Mutant::Mutator::Node::NamedValue::VariableAssignment, 'mutations' do
 
     let(:mutations) do
       mutations = []
-      mutations << 'srandom = true'
+      mutations << 'a__mutant__ = true'
       mutations << 'a = false'
       mutations << 'a = nil'
       mutations << 'nil'
diff --git a/spec/unit/mutant/mutator/node/op_assgn_spec.rb b/spec/unit/mutant/mutator/node/op_assgn_spec.rb
index 5c044108..cb3f1501 100644
--- a/spec/unit/mutant/mutator/node/op_assgn_spec.rb
+++ b/spec/unit/mutant/mutator/node/op_assgn_spec.rb
@@ -3,8 +3,6 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'op_asgn' do
-  let(:random_fixnum) { 5 }
-
   let(:source) { '@a.b += 1' }
 
   let(:mutations) do
@@ -13,7 +11,6 @@ describe Mutant::Mutator::Node::Generic, 'op_asgn' do
     mutations << '@a.b += 2'
     mutations << '@a.b += 0'
     mutations << '@a.b += nil'
-    mutations << '@a.b += 5'
     mutations << 'nil.b += 1'
     mutations << 'nil'
     # TODO: fix invalid AST
@@ -21,9 +18,5 @@ describe Mutant::Mutator::Node::Generic, 'op_asgn' do
     mutations << s(:op_asgn, s(:ivar, :@a), :+, s(:int, 1))
   end
 
-  before do
-    Mutant::Random.stub(fixnum: random_fixnum)
-  end
-
   it_should_behave_like 'a mutator'
 end
diff --git a/spec/unit/mutant/mutator/node/or_asgn_spec.rb b/spec/unit/mutant/mutator/node/or_asgn_spec.rb
index 051daa08..20836008 100644
--- a/spec/unit/mutant/mutator/node/or_asgn_spec.rb
+++ b/spec/unit/mutant/mutator/node/or_asgn_spec.rb
@@ -3,25 +3,17 @@
 require 'spec_helper'
 
 describe Mutant::Mutator::Node::OpAsgn, 'or_asgn' do
-  let(:random_fixnum) { 5        }
-  let(:random_string) { 'random' }
-
   let(:source)  { 'a ||= 1' }
 
   let(:mutations) do
     mutations = []
-    mutations << 'srandom ||= 1'
+    mutations << 'a__mutant__ ||= 1'
     mutations << 'a ||= nil'
     mutations << 'a ||= 0'
     mutations << 'a ||= -1'
     mutations << 'a ||= 2'
-    mutations << 'a ||= 5'
     mutations << 'nil'
   end
 
-  before do
-    Mutant::Random.stub(fixnum: random_fixnum, hex_string: random_string)
-  end
-
   it_should_behave_like 'a mutator'
 end
diff --git a/spec/unit/mutant/mutator/node/rescue_spec.rb b/spec/unit/mutant/mutator/node/rescue_spec.rb
index 504f404c..81385d38 100644
--- a/spec/unit/mutant/mutator/node/rescue_spec.rb
+++ b/spec/unit/mutant/mutator/node/rescue_spec.rb
@@ -4,10 +4,6 @@ require 'spec_helper'
 
 describe Mutant::Mutator::Node::Generic, 'rescue' do
 
-  before do
-    Mutant::Random.stub(hex_string: 'random')
-  end
-
   context 'multiple exception selectors and assignment' do
     let(:source) { 'begin; rescue ExceptionA, ExceptionB => error; true; end' }