1 files changed, 103 insertions, 0 deletions
diff --git a/test/prism/library_symbols_test.rb b/test/prism/library_symbols_test.rb
new file mode 100644
index 0000000000..53f56d9bfa
--- /dev/null
+++ b/test/prism/library_symbols_test.rb
@@ -0,0 +1,103 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+return if RUBY_PLATFORM !~ /linux/
+
+module YARP
+  #
+  #  examine a yarp dll or static archive for expected external symbols.
+  #  these tests only work on a linux system right now.
+  #
+  class LibrarySymbolsTest < TestCase
+    def setup
+      super
+
+      @librubyparser_a = File.expand_path("../../build/librubyparser.a", __dir__)
+      @librubyparser_so = File.expand_path("../../build/librubyparser.so", __dir__)
+      @yarp_so = File.expand_path("../../lib/yarp/yarp.so", __dir__)
+    end
+
+    # objdump runner and helpers
+    def objdump(path)
+      assert_path_exist(path)
+      %x(objdump --section=.text --syms #{path}).split("\n")
+    end
+
+    def global_objdump_symbols(path)
+      objdump(path).select { |line| line[17] == "g" }
+    end
+
+    def hidden_global_objdump_symbols(path)
+      global_objdump_symbols(path).select { |line| line =~ / \.hidden / }
+    end
+
+    def visible_global_objdump_symbols(path)
+      global_objdump_symbols(path).reject { |line| line =~ / \.hidden / }
+    end
+
+    # nm runner and helpers
+    def nm(path)
+      assert_path_exist(path)
+      %x(nm #{path}).split("\n")
+    end
+
+    def global_nm_symbols(path)
+      nm(path).select { |line| line[17] == "T" }
+    end
+
+    def local_nm_symbols(path)
+      nm(path).select { |line| line[17] == "t" }
+    end
+
+    # dig the symbol name out of each line. works for both `objdump` and `nm` output.
+    def names(symbol_lines)
+      symbol_lines.map { |line| line.split(/\s+/).last }
+    end
+
+    #
+    #  static archive - librubyparser.a
+    #
+    def test_librubyparser_a_contains_nothing_globally_visible
+      omit("librubyparser.a is not built") unless File.exist?(@librubyparser_a)
+
+      assert_empty(names(visible_global_objdump_symbols(@librubyparser_a)))
+    end
+
+    def test_librubyparser_a_contains_hidden_yp_symbols
+      omit("librubyparser.a is not built") unless File.exist?(@librubyparser_a)
+
+      names(hidden_global_objdump_symbols(@librubyparser_a)).tap do |symbols|
+        assert_includes(symbols, "yp_parse")
+        assert_includes(symbols, "yp_version")
+      end
+    end
+
+    #
+    #  shared object - librubyparser.so
+    #
+    def test_librubyparser_so_exports_only_the_necessary_functions
+      omit("librubyparser.so is not built") unless File.exist?(@librubyparser_so)
+
+      names(global_nm_symbols(@librubyparser_so)).tap do |symbols|
+        assert_includes(symbols, "yp_parse")
+        assert_includes(symbols, "yp_version")
+      end
+      names(local_nm_symbols(@librubyparser_so)).tap do |symbols|
+        assert_includes(symbols, "yp_encoding_shift_jis_isupper_char")
+      end
+      # TODO: someone who uses this library needs to finish this test
+    end
+
+    #
+    #  shared object - yarp.so
+    #
+    def test_yarp_so_exports_only_the_C_extension_init_function
+      omit("yarp.so is not built") unless File.exist?(@yarp_so)
+
+      names(global_nm_symbols(@yarp_so)).tap do |symbols|
+        assert_equal(["Init_yarp"], symbols)
+      end
+    end
+  end
+end