[Fix #8158] Fix Style/MultilineWhenThen to better handle multiline body

CHANGELOG.md

@@ -20,6 +20,7 @@
 * [#8527](https://github.com/rubocop-hq/rubocop/pull/8527): Prevent an incorrect auto-correction for `Style/CaseEquality` cop when comparing with `===` against a regular expression receiver. ([@koic][])
 * [#8524](https://github.com/rubocop-hq/rubocop/issues/8524): Fix `Layout/EmptyLinesAroundClassBody`  and `Layout/EmptyLinesAroundModuleBody` to correctly handle an access modifier as a first child. ([@dsavochkin][])
 * [#8518](https://github.com/rubocop-hq/rubocop/issues/8518): Fix `Lint/ConstantResolution` cop reporting offense for `module` and `class` definitions. ([@tejasbubane][])
+* [#8158](https://github.com/rubocop-hq/rubocop/issues/8158): Fix `Style/MultilineWhenThen` cop to correctly handle cases with multiline body. ([@dsavochkin][])
 
 ### Changes
 

lib/rubocop/cop/style/multiline_when_then.rb

@@ -44,7 +44,7 @@ def on_when(node)
           # Requires `then` for write `when` and its body on the same line.
           return if require_then?(node)
 
-          # With more than one statements after then, there's not offense
+          # For arrays and hashes there's no offense
           return if accept_node_type?(node.body)
 
           range = node.loc.begin
@@ -64,7 +64,7 @@ def require_then?(when_node)
         end
 
         def accept_node_type?(node)
-          node&.begin_type? || node&.array_type? || node&.hash_type?
+          node&.array_type? || node&.hash_type?
         end
       end
     end

spec/rubocop/cop/style/multiline_when_then_spec.rb

@@ -18,7 +18,7 @@
     RUBY
   end
 
-  it 'registers an offense for multiline when statement with then' do
+  it 'registers an offense for multiline (one line in a body) when statement with then' do
     expect_offense(<<~RUBY)
       case foo
       when bar then
@@ -35,6 +35,25 @@
     RUBY
   end
 
+  it 'registers an offense for multiline (two lines in a body) when statement with then' do
+    expect_offense(<<~RUBY)
+      case foo
+      when bar then
+               ^^^^ Do not use `then` for multiline `when` statement.
+      do_something1
+      do_something2
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      case foo
+      when bar
+      do_something1
+      do_something2
+      end
+    RUBY
+  end
+
   it "doesn't register an offense for singleline when statement with then" do
     expect_no_offenses(<<~RUBY)
       case foo