1 files changed, 47 insertions, 0 deletions
diff --git a/test/csv/interface/test_delegation.rb b/test/csv/interface/test_delegation.rb
new file mode 100644
index 0000000000..349257633b
--- /dev/null
+++ b/test/csv/interface/test_delegation.rb
@@ -0,0 +1,47 @@
+# frozen_string_literal: false
+
+require_relative "../helper"
+
+class TestCSVInterfaceDelegation < Test::Unit::TestCase
+  class TestStringIO < self
+    def setup
+      @csv = CSV.new("h1,h2")
+    end
+
+    def test_flock
+      assert_raise(NotImplementedError) do
+        @csv.flock(File::LOCK_EX)
+      end
+    end
+
+    def test_ioctl
+      assert_raise(NotImplementedError) do
+        @csv.ioctl(0)
+      end
+    end
+
+    def test_stat
+      assert_raise(NotImplementedError) do
+        @csv.stat
+      end
+    end
+
+    def test_to_i
+      assert_raise(NotImplementedError) do
+        @csv.to_i
+      end
+    end
+
+    def test_binmode?
+      assert_equal(false, @csv.binmode?)
+    end
+
+    def test_path
+      assert_equal(nil, @csv.path)
+    end
+
+    def test_to_io
+      assert_instance_of(StringIO, @csv.to_io)
+    end
+  end
+end