1 files changed, 21 insertions, 0 deletions
diff --git a/mrbgems/mruby-string-ext/test/string.rb b/mrbgems/mruby-string-ext/test/string.rb
index 0ef92b35a..72c919b35 100644
--- a/mrbgems/mruby-string-ext/test/string.rb
+++ b/mrbgems/mruby-string-ext/test/string.rb
@@ -172,3 +172,24 @@ assert('String#lines') do
   assert_equal ["\n", "\n", "\n"], "\n\n\n".lines
   assert_equal [], "".lines
 end
+
+assert('String#clear') do
+  # embed string
+  s = "foo"
+  assert_equal("", s.clear)
+  assert_equal("", s)
+
+  # not embed string and not shared string
+  s = "foo" * 100
+  a = s
+  assert_equal("", s.clear)
+  assert_equal("", s)
+  assert_equal("", a)
+
+  # shared string
+  s = "foo" * 100
+  a = s[10, 90]                # create shared string
+  assert_equal("", s.clear)    # clear
+  assert_equal("", s)          # s is cleared
+  assert_not_equal("", a)      # a should not be affected
+end