1 files changed, 59 insertions, 0 deletions
diff --git a/test/prism/bom_test.rb b/test/prism/bom_test.rb
new file mode 100644
index 0000000000..1525caf458
--- /dev/null
+++ b/test/prism/bom_test.rb
@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+# Don't bother checking this on these engines, this is such a specific Ripper
+# test.
+return if RUBY_ENGINE == "jruby" || RUBY_ENGINE == "truffleruby"
+
+require_relative "test_helper"
+
+module Prism
+  class BOMTest < TestCase
+    def test_ident
+      assert_bom("foo")
+    end
+
+    def test_back_reference
+      assert_bom("$+")
+    end
+
+    def test_instance_variable
+      assert_bom("@foo")
+    end
+
+    def test_class_variable
+      assert_bom("@@foo")
+    end
+
+    def test_global_variable
+      assert_bom("$foo")
+    end
+
+    def test_numbered_reference
+      assert_bom("$1")
+    end
+
+    def test_percents
+      assert_bom("%i[]")
+      assert_bom("%r[]")
+      assert_bom("%s[]")
+      assert_bom("%q{}")
+      assert_bom("%w[]")
+      assert_bom("%x[]")
+      assert_bom("%I[]")
+      assert_bom("%W[]")
+      assert_bom("%Q{}")
+    end
+
+    def test_string
+      assert_bom("\"\"")
+      assert_bom("''")
+    end
+
+    private
+
+    def assert_bom(source)
+      bommed = "\xEF\xBB\xBF#{source}"
+      assert_equal Prism.lex_ripper(bommed), Prism.lex_compat(bommed).value
+    end
+  end
+end