Remove integer literal negation mutation

- Removes mutations of the form of `1` -> `-1`. These are unlikely to yield alive mutations and sometimes lead to frustrating, equivalent mutations.

lib/mutant/mutator/node/literal/integer.rb

@@ -9,6 +9,8 @@ class Integer < self
 
           handle(:int)
 
+          children :value
+
         private
 
           def dispatch
@@ -17,12 +19,7 @@ def dispatch
           end
 
           def values
-            [0, 1, -value, value + 1, value - 1]
-          end
-
-          def value
-            value, = children
-            value
+            [0, 1, value + 1, value - 1]
           end
 
         end # Integer

meta/and_asgn.rb

@@ -8,6 +8,5 @@
   mutation 'a__mutant__ &&= 1'
   mutation 'a &&= nil'
   mutation 'a &&= 0'
-  mutation 'a &&= -1'
   mutation 'a &&= 2'
 end

meta/index.rb

@@ -25,7 +25,6 @@
   mutation 'self[1]'
   mutation 'foo[0]'
   mutation 'foo[2]'
-  mutation 'foo[-1]'
   mutation 'foo[nil]'
 end
 
@@ -43,7 +42,6 @@
   mutation 'foo[nil]'
   mutation 'foo[n..nil]'
   mutation 'foo[n..-1]'
-  mutation 'foo[n..2]'
   mutation 'foo[n..0]'
   mutation 'foo[n..1]'
   mutation 'foo[n..-3]'

meta/int.rb

@@ -9,9 +9,6 @@
   mutation '0'
   mutation '1'
 
-  # negative
-  mutation '-10'
-
   # scalar boundary
   mutation '9'
   mutation '11'

meta/ivasgn.rb

@@ -16,6 +16,5 @@
   mutation '@a__mutant__ &&= 1'
   mutation '@a &&= nil'
   mutation '@a &&= 0'
-  mutation '@a &&= -1'
   mutation '@a &&= 2'
 end

meta/op_assgn.rb

@@ -6,7 +6,6 @@
   singleton_mutations
 
   mutation '@a += 1'
-  mutation '@a.b += -1'
   mutation '@a.b += 0'
   mutation '@a.b += 2'
   mutation '@a.b += nil'
@@ -19,7 +18,6 @@
 
   singleton_mutations
 
-  mutation 'a.b += -1'
   mutation 'a.b += 0'
   mutation 'a.b += 2'
   mutation 'a.b += nil'
@@ -32,7 +30,6 @@
   singleton_mutations
 
   mutation 'b__mutant__ += 1'
-  mutation 'b += -1'
   mutation 'b += 0'
   mutation 'b += 2'
   mutation 'b += nil'

meta/or_asgn.rb

@@ -7,7 +7,6 @@
   mutation 'a__mutant__ ||= 1'
   mutation 'a ||= nil'
   mutation 'a ||= 0'
-  mutation 'a ||= -1'
   mutation 'a ||= 2'
 end
 
@@ -17,7 +16,6 @@
   singleton_mutations
   mutation '@a ||= nil'
   mutation '@a ||= 0'
-  mutation '@a ||= -1'
   mutation '@a ||= 2'
 end
 
@@ -42,6 +40,5 @@
   singleton_mutations
   mutation 'foo[:bar] ||= nil'
   mutation 'foo[:bar] ||= 0'
-  mutation 'foo[:bar] ||= -1'
   mutation 'foo[:bar] ||= 2'
 end

meta/range.rb

@@ -5,7 +5,6 @@
 
   singleton_mutations
   mutation '1...100'
-  mutation '-1..100'
   mutation '0..100'
   mutation '2..100'
   mutation 'nil..100'
@@ -14,15 +13,13 @@
   mutation '1..1'
   mutation '1..99'
   mutation '1..101'
-  mutation '1..-100'
 end
 
 Mutant::Meta::Example.add :erange do
   source '1...100'
 
   singleton_mutations
   mutation '1..100'
-  mutation '-1...100'
   mutation '0...100'
   mutation '2...100'
   mutation 'nil...100'
@@ -31,15 +28,13 @@
   mutation '1...1'
   mutation '1...99'
   mutation '1...101'
-  mutation '1...-100'
 end
 
 unless RUBY_VERSION.start_with?('2.5')
   Mutant::Meta::Example.add :erange do
     source '1...'
 
     singleton_mutations
-    mutation '-1...'
     mutation '0...'
     mutation '2...'
     mutation 'nil...'
@@ -49,7 +44,6 @@
     source '1..'
 
     singleton_mutations
-    mutation '-1..'
     mutation '0..'
     mutation '2..'
     mutation 'nil..'

meta/send.rb

@@ -343,7 +343,6 @@
   mutation 'foo.public_send(1, two: true, **kwargs, &block)'
   mutation 'foo.public_send(:bar, nil, two: true, **kwargs, &block)'
   mutation 'foo.public_send(:bar, 0, two: true, **kwargs, &block)'
-  mutation 'foo.public_send(:bar, -1, two: true, **kwargs, &block)'
   mutation 'foo.public_send(:bar, 2, two: true, **kwargs, &block)'
   mutation 'foo.public_send(:bar, two: true, **kwargs, &block)'
   mutation 'foo.public_send(:bar, 1, two__mutant__: true, **kwargs, &block)'
@@ -738,7 +737,6 @@
   mutation 'match?(/\Afoo/)'
   mutation 'match?(1)'
   mutation 'match?(/\Afoo/, nil)'
-  mutation 'match?(/\Afoo/, -1)'
   mutation 'match?(/\Afoo/, 0)'
   mutation 'match?(/\Afoo/, 2)'
   mutation 'match?'