[Fix rubocop#3568] Detect style while handling offense in VariableNumber

When the variable name doesn't match the configured style, we should
detect which style is used so that the right information is
generated in .rubocop_todo.yml.

CHANGELOG.md

@@ -20,6 +20,7 @@
 * [#3662](https://github.com/bbatsov/rubocop/issues/3662): Fix the auto-correction of `Lint/UnneededSplatExpansion` when the splat expansion is inside of another array. ([@rrosenblum][])
 * [#3699](https://github.com/bbatsov/rubocop/issues/3699): Fix false positive in `Style/VariableNumber` on variable names ending with an underscore. ([@bquorning][])
 * [#3687](https://github.com/bbatsov/rubocop/issues/3687): Fix the fact that `Style/TernaryParentheses` cop claims to correct uncorrected offenses. ([@Ana06][])
+* [#3568](https://github.com/bbatsov/rubocop/issues/3568): Fix `--auto-gen-config` behavior for `Style/VariableNumber`. ([@jonas054][])
 
 ## 0.45.0 (2016-10-31)
 

lib/rubocop/cop/mixin/configurable_numbering.rb

@@ -14,16 +14,23 @@ module ConfigurableNumbering
       def check_name(node, name, name_range)
         return if operator?(name)
 
-        if valid_name?(node, name)
+        if valid_name?(node, name, style)
           correct_style_detected
         else
-          add_offense(node, name_range, message(style))
+          add_offense(node, name_range, message(style)) do
+            (supported_styles - [style]).each do |other_style|
+              if valid_name?(node, name, other_style)
+                unexpected_style_detected(other_style)
+                break
+              end
+            end
+          end
         end
       end
 
-      def valid_name?(node, name)
+      def valid_name?(node, name, given_style)
         pattern =
-          case style
+          case given_style
           when :snake_case
             SNAKE_CASE
           when :normalcase

spec/rubocop/cop/style/variable_number_spec.rb

@@ -5,12 +5,19 @@
 describe RuboCop::Cop::Style::VariableNumber, :config do
   subject(:cop) { described_class.new(config) }
 
-  shared_examples :offense do |style, variable|
-    it "registers an offense for #{variable} in #{style}" do
-      inspect_source(cop, "#{variable} = 1")
+  shared_examples :offense do |style, variable, style_to_allow_offenses|
+    it "registers an offense for #{Array(variable).first} in #{style}" do
+      inspect_source(cop, Array(variable).map { |v| "#{v} = 1" }.join("\n"))
 
       expect(cop.messages).to eq(["Use #{style} for variable numbers."])
-      expect(cop.highlights).to eq([variable])
+      expect(cop.highlights).to eq(Array(variable)[0, 1])
+      config_to_allow_offenses =
+        if style_to_allow_offenses
+          { 'EnforcedStyle' => style_to_allow_offenses.to_s }
+        else
+          { 'Enabled' => false }
+        end
+      expect(cop.config_to_allow_offenses).to eq(config_to_allow_offenses)
     end
   end
 
@@ -25,13 +32,14 @@
   context 'when configured for snake_case' do
     let(:cop_config) { { 'EnforcedStyle' => 'snake_case' } }
 
-    it_behaves_like :offense, 'snake_case', 'local1'
-    it_behaves_like :offense, 'snake_case', '@local1'
-    it_behaves_like :offense, 'snake_case', '@@local1'
-    it_behaves_like :offense, 'snake_case', 'camelCase1'
-    it_behaves_like :offense, 'snake_case', '@camelCase1'
-    it_behaves_like :offense, 'snake_case', '_unused1'
-    it_behaves_like :offense, 'snake_case', 'aB1'
+    it_behaves_like :offense, 'snake_case', 'local1', :normalcase
+    it_behaves_like :offense, 'snake_case', '@local1', :normalcase
+    it_behaves_like :offense, 'snake_case', '@@local1', :normalcase
+    it_behaves_like :offense, 'snake_case', 'camelCase1', :normalcase
+    it_behaves_like :offense, 'snake_case', '@camelCase1', :normalcase
+    it_behaves_like :offense, 'snake_case', '_unused1', :normalcase
+    it_behaves_like :offense, 'snake_case', 'aB1', :normalcase
+    it_behaves_like :offense, 'snake_case', %w(a1 a_2), nil
 
     it_behaves_like :accepts, 'snake_case', 'local_1'
     it_behaves_like :accepts, 'snake_case', 'local_12'
@@ -62,15 +70,16 @@
   context 'when configured for normal' do
     let(:cop_config) { { 'EnforcedStyle' => 'normalcase' } }
 
-    it_behaves_like :offense, 'normalcase', 'local_1'
-    it_behaves_like :offense, 'normalcase', 'sha_256'
-    it_behaves_like :offense, 'normalcase', '@local_1'
-    it_behaves_like :offense, 'normalcase', '@@local_1'
-    it_behaves_like :offense, 'normalcase', 'myAttribute_1'
-    it_behaves_like :offense, 'normalcase', '@myAttribute_1'
-    it_behaves_like :offense, 'normalcase', '_myLocal_1'
-    it_behaves_like :offense, 'normalcase', 'localFOO_1'
-    it_behaves_like :offense, 'normalcase', 'local_FOO_1'
+    it_behaves_like :offense, 'normalcase', 'local_1', :snake_case
+    it_behaves_like :offense, 'normalcase', 'sha_256', :snake_case
+    it_behaves_like :offense, 'normalcase', '@local_1', :snake_case
+    it_behaves_like :offense, 'normalcase', '@@local_1', :snake_case
+    it_behaves_like :offense, 'normalcase', 'myAttribute_1', :snake_case
+    it_behaves_like :offense, 'normalcase', '@myAttribute_1', :snake_case
+    it_behaves_like :offense, 'normalcase', '_myLocal_1', :snake_case
+    it_behaves_like :offense, 'normalcase', 'localFOO_1', :snake_case
+    it_behaves_like :offense, 'normalcase', 'local_FOO_1', :snake_case
+    it_behaves_like :offense, 'normalcase', %w(a_1 a2), nil
 
     it_behaves_like :accepts, 'normalcase', 'local1'
     it_behaves_like :accepts, 'normalcase', 'local_'
@@ -103,16 +112,17 @@
   context 'when configured for non integer' do
     let(:cop_config) { { 'EnforcedStyle' => 'non_integer' } }
 
-    it_behaves_like :offense, 'non_integer', 'local_1'
-    it_behaves_like :offense, 'non_integer', 'local1'
-    it_behaves_like :offense, 'non_integer', '@local_1'
-    it_behaves_like :offense, 'non_integer', '@local1'
-    it_behaves_like :offense, 'non_integer', 'myAttribute_1'
-    it_behaves_like :offense, 'non_integer', 'myAttribute1'
-    it_behaves_like :offense, 'non_integer', '@myAttribute_1'
-    it_behaves_like :offense, 'non_integer', '@myAttribute1'
-    it_behaves_like :offense, 'non_integer', '_myLocal_1'
-    it_behaves_like :offense, 'non_integer', '_myLocal1'
+    it_behaves_like :offense, 'non_integer', 'local_1', :snake_case
+    it_behaves_like :offense, 'non_integer', 'local1', :normalcase
+    it_behaves_like :offense, 'non_integer', '@local_1', :snake_case
+    it_behaves_like :offense, 'non_integer', '@local1', :normalcase
+    it_behaves_like :offense, 'non_integer', 'myAttribute_1', :snake_case
+    it_behaves_like :offense, 'non_integer', 'myAttribute1', :normalcase
+    it_behaves_like :offense, 'non_integer', '@myAttribute_1', :snake_case
+    it_behaves_like :offense, 'non_integer', '@myAttribute1', :normalcase
+    it_behaves_like :offense, 'non_integer', '_myLocal_1', :snake_case
+    it_behaves_like :offense, 'non_integer', '_myLocal1', :normalcase
+    it_behaves_like :offense, 'non_integer', %w(a_1 aone), nil
 
     it_behaves_like :accepts, 'non_integer', 'localone'
     it_behaves_like :accepts, 'non_integer', 'local_one'