Add spec for Polyglot.import and Truffle::Interop.import

Author: eregon

spec/truffle/interop/import_spec.rb

@@ -0,0 +1,25 @@
+# Copyright (c) 2019 Oracle and/or its affiliates. All rights reserved. This
+# code is released under a tri EPL/GPL/LGPL license. You can use it,
+# redistribute it and/or modify it under the terms of the:
+#
+# Eclipse Public License version 1.0, or
+# GNU General Public License version 2, or
+# GNU Lesser General Public License version 2.1.
+
+require_relative '../../ruby/spec_helper'
+
+guard -> { Truffle::Interop.polyglot_access? } do
+  describe "Truffle::Interop.import" do
+
+    it "imports an object" do
+      object = Object.new
+      Truffle::Interop.export :imports_an_object, object
+      Truffle::Interop.import(:imports_an_object).should == object
+    end
+
+    it "returns nil because Truffle::Interop.lookup_symbol returns nil if not found" do
+      Truffle::Interop.import(:not_registered_export_test).should == nil
+    end
+
+  end
+end