Add a test for disabled rpath

Author: larskanis

test/rcd_test/test/test_basic.rb

@@ -35,4 +35,15 @@ def test_largefile_op_removed_from_musl
     is_linux = RUBY_PLATFORM.include?("linux")
     assert_equal(is_linux, RcdTest.largefile_op_removed_from_musl)
   end
+
+  def test_disabled_rpath
+    skip("jruby uses jar files without rpath") if RUBY_ENGINE == "jruby"
+
+    cext_fname = $LOADED_FEATURES.grep(/rcd_test_ext/).first
+    refute_nil(cext_fname, "the C-ext should be loaded")
+    cext_text = File.binread(cext_fname)
+    assert_match(/Init_rcd_test_ext/, cext_text, "C-ext shoud contain the init function")
+    refute_match(/usr\/local/, cext_text, "there should be no rpath to /usr/local/rake-compiler/ruby/x86_64-unknown-linux-musl/ruby-3.4.5/lib or so")
+    refute_match(/home\//, cext_text, "there should be no path to /home/ or so")
+  end
 end