Suggest reserved words if they match

lib/did_you_mean/spell_checkers/method_name_checker.rb

@@ -7,14 +7,43 @@ class MethodNameChecker
     NAMES_TO_EXCLUDE = { NilClass => nil.methods }
     NAMES_TO_EXCLUDE.default = []
 
+    # +MethodNameChecker::RB_RESERVED_WORDS+ is the list of reserved words in
+    # Ruby that take an argument. Unlike
+    # +VariableNameChecker::RB_RESERVED_WORDS+, those reserved words reqquires
+    # an argument, and a +NoMethodError+ is raised due to the presence of the
+    # argument.
+    #
+    # The +MethodNameChecker+ will use this list to suggest a reversed word if
+    # a +NoMethodError+ is raised and found closest matches.
+    #
+    # Also see +VariableNameChecker::RB_RESERVED_WORDS+.
+    RB_RESERVED_WORDS = %i(
+      alias
+      case
+      def
+      defined?
+      elsif
+      end
+      ensure
+      for
+      rescue
+      super
+      undef
+      unless
+      until
+      when
+      while
+      yield
+    )
+
     def initialize(exception)
       @method_name  = exception.name
       @receiver     = exception.receiver
       @private_call = exception.respond_to?(:private_call?) ? exception.private_call? : false
     end
 
     def corrections
-      @corrections ||= SpellChecker.new(dictionary: method_names).correct(method_name) - NAMES_TO_EXCLUDE[@receiver.class]
+      @corrections ||= SpellChecker.new(dictionary: RB_RESERVED_WORDS + method_names).correct(method_name) - NAMES_TO_EXCLUDE[@receiver.class]
     end
 
     def method_names

lib/did_you_mean/spell_checkers/name_error_checkers/variable_name_checker.rb

@@ -6,9 +6,61 @@ module DidYouMean
   class VariableNameChecker
     attr_reader :name, :method_names, :lvar_names, :ivar_names, :cvar_names
 
-    NAMES_TO_EXCLUDE = { 'foo' => [:fork] }
+    NAMES_TO_EXCLUDE = { 'foo' => [:fork, :for] }
     NAMES_TO_EXCLUDE.default = []
-    RB_PREDEFINED_OBJECTS = [:false, :true, :nil, :yield]
+
+    # +VariableNameChecker::RB_RESERVED_WORDS+ is the list of all reserved
+    # words in Ruby. They could be declared like methods are, and a typo would
+    # cause Ruby to raise a +NameError+ because of the way they are declared.
+    #
+    # The +:VariableNameChecker+ will use this list to suggest a reversed word
+    # if a +NameError+ is raised and found closest matches, excluding:
+    #
+    #   * +do+
+    #   * +if+
+    #   * +in+
+    #   * +or+
+    #
+    # Also see +MethodNameChecker::RB_RESERVED_WORDS+.
+    RB_RESERVED_WORDS = %i(
+      BEGIN
+      END
+      alias
+      and
+      begin
+      break
+      case
+      class
+      def
+      defined?
+      else
+      elsif
+      end
+      ensure
+      false
+      for
+      module
+      next
+      nil
+      not
+      redo
+      rescue
+      retry
+      return
+      self
+      super
+      then
+      true
+      undef
+      unless
+      until
+      when
+      while
+      yield
+      __LINE__
+      __FILE__
+      __ENCODING__
+    )
 
     def initialize(exception)
       @name       = exception.name.to_s.tr("@", "")
@@ -23,7 +75,7 @@ def initialize(exception)
 
     def corrections
       @corrections ||= SpellChecker
-                     .new(dictionary: (RB_PREDEFINED_OBJECTS + lvar_names + method_names + ivar_names + cvar_names))
+                     .new(dictionary: (RB_RESERVED_WORDS + lvar_names + method_names + ivar_names + cvar_names))
                      .correct(name) - NAMES_TO_EXCLUDE[@name]
     end
   end

test/spell_checking/method_name_check_test.rb

@@ -116,4 +116,11 @@ def test_does_not_append_suggestions_three_times
 
     assert_equal 1, error.to_s.scan(/Did you mean/).count
   end
+
+  def test_suggests_yield
+    error = assert_raises(NoMethodError) { yeild(1) }
+
+    assert_correction :yield, error.corrections
+    assert_match "Did you mean?  yield", error.to_s
+  end
 end

test/spell_checking/variable_name_check_test.rb

@@ -69,7 +69,11 @@ def test_corrections_include_ruby_predefined_objects
     end
 
     nil_error = assert_raises(NameError) do
-      some_var = nol
+      some_var = nul
+    end
+
+    file_error = assert_raises(NameError) do
+      __FIEL__
     end
 
     assert_correction :false, false_error.corrections
@@ -80,6 +84,9 @@ def test_corrections_include_ruby_predefined_objects
 
     assert_correction :nil, nil_error.corrections
     assert_match "Did you mean?  nil", nil_error.to_s
+
+    assert_correction :__FILE__, file_error.corrections
+    assert_match "Did you mean?  __FILE__", file_error.to_s
   end
 
   def test_suggests_yield