add a regression test for #1706

mrbgems/mruby-bin-mirb/bintest/mirb.rb

@@ -10,3 +10,26 @@ assert('regression for #1563') do
   o, s = Open3.capture2('bin/mirb', :stdin_data => "a=1;b=2;c=3\nb\nc")
   assert_true o.include?('=> 3')
 end
+
+assert('regression for #1706') do
+  o, s = Open3.capture2('bin/mirb', :stdin_data => %{
+    if false
+      a = 1
+      b = 1
+    end
+    puts "a: \#{a.inspect}"
+    puts "b: \#{b.inspect}"
+  })
+  assert_true o.include?('a: nil')
+  assert_true o.include?('b: nil')
+
+  o, s = Open3.capture2('bin/mirb', :stdin_data => %{
+    a = 1
+    b = 2
+    if false
+      c = 3
+    end
+    puts "c: \#{c.inspect}"
+  })
+  assert_true o.include?('c: nil')
+end