[Fix rubocop#4283] Style/EmptyCaseCondition autocorrect bugfix

When first `when` condition of an empty case included comma-delimited
alternatives, autocorrect did not replace the comma with `||`.
This commit fixes the issue.

CHANGELOG.md

@@ -23,6 +23,7 @@
 * [#4241](https://github.com/bbatsov/rubocop/issues/4241): Prevent `Rails/Blank` and `Rails/Present` from breaking when there is no explicit receiver. ([@rrosenblum][])
 * [#4249](https://github.com/bbatsov/rubocop/issues/4249): Handle multiple assignment in `Rails/RelativeDateConstant`. ([@bbatsov][])
 * [#4250](https://github.com/bbatsov/rubocop/issues/4250): Improve a bit the Ruby code detection config. ([@bbatsov][])
+* [#4283](https://github.com/bbatsov/rubocop/issues/4283): Fix `Style/EmptyCaseCondition` autocorrect bug - when first `when` branch includes comma-delimited alternatives. ([@ilansh][])
 * [#4268](https://github.com/bbatsov/rubocop/issues/4268): Handle end-of-line comments when autocorrecting Style/EmptyLinesAroundAccessModifier. ([@vergenzt][])
 * [#4275](https://github.com/bbatsov/rubocop/issues/4275): Prevent `Style/MethodCallWithArgsParentheses` from blowing up on `yield`. ([@drenmi][])
 * [#3969](https://github.com/bbatsov/rubocop/issues/3969): Handle multiline method call alignment for arguments to methods. ([@jonas054][])
@@ -2755,3 +2756,4 @@
 [@sadovnik]: https://github.com/sadovnik
 [@cjlarose]: https://github.com/cjlarose
 [@alpaca-tc]: https://github.com/alpaca-tc
+[@ilansh]: https://github.com/ilansh

lib/rubocop/cop/style/empty_case_condition.rb

@@ -57,11 +57,11 @@ def autocorrect(case_node)
         end
 
         def correct_case_when(corrector, case_node, when_nodes)
-          case_range = case_node.loc.keyword.join(when_nodes.shift.loc.keyword)
+          case_range = case_node.loc.keyword.join(when_nodes.first.loc.keyword)
 
           corrector.replace(case_range, 'if')
 
-          when_nodes.each do |when_node|
+          when_nodes[1..-1].each do |when_node|
             corrector.replace(when_node.loc.keyword, 'elsif')
           end
         end

spec/rubocop/cop/style/empty_case_condition_spec.rb

@@ -167,5 +167,29 @@
 
       it_behaves_like 'detect/correct empty case, accept non-empty case'
     end
+
+    context 'with first when branch including comma-delimited alternatives' do
+      let(:source) do
+        <<-END.strip_indent
+          case
+          when my.foo?, my.bar?
+            something
+          when my.baz?
+            something_else
+          end
+        END
+      end
+      let(:corrected_source) do
+        <<-END.strip_indent
+          if my.foo? || my.bar?
+            something
+          elsif my.baz?
+            something_else
+          end
+        END
+      end
+
+      it_behaves_like 'detect/correct empty case, accept non-empty case'
+    end
   end
 end