From a756dae95b75b1dec6ae4510fe060247ed477c3c Mon Sep 17 00:00:00 2001
From: Markus Schirp <mbj@schirp-dso.com>
Date: Fri, 9 Feb 2024 16:38:47 +0000
Subject: [PATCH] Fix mutation to invalid hash pattern

[fix #1417]
---
 lib/mutant/mutator/node/literal/hash.rb |  4 +++-
 meta/case.rb                            | 14 ++++++++++++++
 meta/def.rb                             |  1 -
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/lib/mutant/mutator/node/literal/hash.rb b/lib/mutant/mutator/node/literal/hash.rb
index 5bdefc219..8dce21773 100644
--- a/lib/mutant/mutator/node/literal/hash.rb
+++ b/lib/mutant/mutator/node/literal/hash.rb
@@ -36,7 +36,9 @@ class Pair < Node
           private
 
             def dispatch
-              emit_key_mutations
+              emit_key_mutations do |mutation|
+                !mutation.eql?(s(:nil))
+              end
               emit_value_mutations
             end
 
diff --git a/meta/case.rb b/meta/case.rb
index b8dd0228d..96b677b25 100644
--- a/meta/case.rb
+++ b/meta/case.rb
@@ -1,5 +1,19 @@
 # frozen_string_literal: true
 
+Mutant::Meta::Example.add :case do
+  source <<-RUBY
+    case nil
+    in { a: nil }
+    end
+  RUBY
+
+  mutation <<~RUBY
+    case nil
+    in {a__mutant__: nil}
+    end
+  RUBY
+end
+
 Mutant::Meta::Example.add :case do
   source <<-RUBY
     case
diff --git a/meta/def.rb b/meta/def.rb
index 44cde4776..01c3ae9c5 100644
--- a/meta/def.rb
+++ b/meta/def.rb
@@ -226,7 +226,6 @@
     mutation 'def foo(**); { ** }; end'
     mutation 'def foo(**); { default: nil }; end'
     mutation 'def foo(**); { default__mutant__: nil, ** }; end'
-    mutation 'def foo(**); { nil => nil, ** }; end'
     mutation 'def foo(**); {}; end'
   end