1 files changed, 105 insertions, 0 deletions
diff --git a/test/ruby/test_case.rb b/test/ruby/test_case.rb
index af925d1ac8..9e8502fb27 100644
--- a/test/ruby/test_case.rb
+++ b/test/ruby/test_case.rb
@@ -1,3 +1,4 @@
+# frozen_string_literal: false
 require 'test/unit'
 
 class TestCase < Test::Unit::TestCase
@@ -52,5 +53,109 @@ class TestCase < Test::Unit::TestCase
     else
       assert(false)
     end
+
+    case
+    when *[], false
+      assert(false)
+    else
+      assert(true)
+    end
+
+    case
+    when *false, []
+      assert(true)
+    else
+      assert(false)
+    end
+
+    begin
+      verbose_bak, $VERBOSE = $VERBOSE, nil
+      assert_raise(NameError) do
+        eval("case; when false, *x, false; end")
+      end
+    ensure
+      $VERBOSE = verbose_bak
+    end
+  end
+
+  def test_deoptimization
+    assert_in_out_err(['-e', <<-EOS], '', %w[42], [])
+      class Symbol; undef ===; def ===(o); p 42; true; end; end; case :foo; when :foo; end
+    EOS
+
+    assert_in_out_err(['-e', <<-EOS], '', %w[42], [])
+      class Integer; undef ===; def ===(o); p 42; true; end; end; case 1; when 1; end
+    EOS
+  end
+
+  def test_optimization
+    case 1
+    when 0.9, 1.1
+      assert(false)
+    when 1.0
+      assert(true)
+    else
+      assert(false)
+    end
+    case 536870912
+    when 536870911.9, 536870912.1
+      assert(false)
+    when 536870912.0
+      assert(true)
+    else
+      assert(false)
+    end
+    case 0
+    when 0r
+      assert(true)
+    else
+      assert(false)
+    end
+    case 0
+    when 0i
+      assert(true)
+    else
+      assert(false)
+    end
+  end
+
+  def test_method_missing
+    flag = false
+
+    case 1
+    when Class.new(BasicObject) { def method_missing(*) true end }.new
+      flag = true
+    end
+
+    assert(flag)
+  end
+
+  def test_nomethoderror
+    assert_raise(NoMethodError) {
+      case 1
+      when Class.new(BasicObject) { }.new
+      end
+    }
+  end
+
+  module NilEqq
+    refine NilClass do
+      def === other
+        false
+      end
+    end
+  end
+
+  class NilEqqClass
+    using NilEqq
+
+    def eqq(a)
+      case a; when nil then nil; else :not_nil; end
+    end
+  end
+
+
+  def test_deoptimize_nil
+    assert_equal :not_nil, NilEqqClass.new.eqq(nil)
   end
 end