Prefer Object#is_a? over #kind_of?

lib/mutant/env.rb

@@ -115,7 +115,7 @@ module Mutant
     def expression(scope)
       name = scope_name(scope) or return
 
-      unless name.kind_of?(String)
+      unless name.is_a?(String)
         warn("#{scope.class}#name from: #{scope.inspect} did not return a String or nil. Fix your lib to support normal ruby semantics!")
         return
       end

lib/mutant/mutator/node/const.rb

@@ -19,7 +19,7 @@ module Mutant
           emit_singletons unless parent_node && n_const?(parent_node)
           emit_type(nil, *children.drop(1))
           children.each_with_index do |child, index|
-            mutate_child(index) if child.kind_of?(Parser::AST::Node)
+            mutate_child(index) if child.is_a?(Parser::AST::Node)
           end
         end
 

lib/mutant/mutator/node/generic.rb

@@ -26,7 +26,7 @@ module Mutant
         #
         def dispatch
           children.each_with_index do |child, index|
-            mutate_child(index) if child.kind_of?(Parser::AST::Node)
+            mutate_child(index) if child.is_a?(Parser::AST::Node)
           end
         end
 

lib/mutant/mutator/registry.rb

@@ -64,7 +64,7 @@ module Mutant
       # @api private
       #
       def self.assert_valid_type(type)
-        unless AST::Types::ALL.include?(type) || type.kind_of?(Class)
+        unless AST::Types::ALL.include?(type) || type.is_a?(Class)
           raise InvalidTypeError, "invalid type registration: #{type}"
         end
       end

lib/mutant/runner.rb

@@ -103,7 +103,7 @@ module Mutant
     # @api private
     #
     def finish(mutation, index, result)
-      return unless result.kind_of?(Mutant::Result::Mutation)
+      return unless result.is_a?(Mutant::Result::Mutation)
 
       test_results = result.test_results.zip(mutation.subject.tests).map do |test_result, test|
         test_result.update(test: test, mutation: mutation) if test_result

meta/send.rb

@@ -145,6 +145,19 @@ Mutant::Meta::Example.add do
   mutation 'foo.instance_of?(bar)'
 end
 
+Mutant::Meta::Example.add do
+  source 'foo.is_a?(bar)'
+
+  singleton_mutations
+  mutation 'foo'
+  mutation 'bar'
+  mutation 'foo.is_a?'
+  mutation 'foo.is_a?(nil)'
+  mutation 'foo.is_a?(self)'
+  mutation 'self.is_a?(bar)'
+  mutation 'foo.instance_of?(bar)'
+end
+
 Mutant::Meta::Example.add do
   source 'foo.kind_of?(bar)'