free_mutant/docs/limitations.md

Limitations

Subject

Mutant cannot emit mutations for some subjects.

• methods defined within a closure. For example, methods defined using module_eval, class_eval, define_method, or define_singleton_method:

  class Example
    class_eval do
      def example1
      end
    end
  
    module_eval do
      def example2
      end
    end
  
    define_method(:example3) do
    end
  
    define_singleton_method(:example4) do
    end
  end
  

• singleton methods not defined on a constant or self

  class Foo
    def self.bar; end   # ok
    def Foo.baz; end    # ok
  
    myself = self
    def myself.qux; end # cannot mutate
  end
  

• methods defined with eval:

  class Foo
    class_eval('def bar; end') # cannot mutate
  end