1 files changed, 186 insertions, 0 deletions
diff --git a/test/prism/parser_test.rb b/test/prism/parser_test.rb
new file mode 100644
index 0000000000..79b65cf75b
--- /dev/null
+++ b/test/prism/parser_test.rb
@@ -0,0 +1,186 @@
+# frozen_string_literal: true
+
+require_relative "test_helper"
+
+begin
+  verbose, $VERBOSE = $VERBOSE, nil
+  require "parser/ruby33"
+  require "prism/translation/parser33"
+rescue LoadError
+  # In CRuby's CI, we're not going to test against the parser gem because we
+  # don't want to have to install it. So in this case we'll just skip this test.
+  return
+ensure
+  $VERBOSE = verbose
+end
+
+# First, opt in to every AST feature.
+Parser::Builders::Default.modernize
+
+# Modify the source map == check so that it doesn't check against the node
+# itself so we don't get into a recursive loop.
+Parser::Source::Map.prepend(
+  Module.new {
+    def ==(other)
+      self.class == other.class &&
+        (instance_variables - %i[@node]).map do |ivar|
+          instance_variable_get(ivar) == other.instance_variable_get(ivar)
+        end.reduce(:&)
+    end
+  }
+)
+
+# Next, ensure that we're comparing the nodes and also comparing the source
+# ranges so that we're getting all of the necessary information.
+Parser::AST::Node.prepend(
+  Module.new {
+    def ==(other)
+      super && (location == other.location)
+    end
+  }
+)
+
+module Prism
+  class ParserTest < TestCase
+    base = File.join(__dir__, "fixtures")
+
+    # These files are erroring because of the parser gem being wrong.
+    skip_incorrect = [
+      "embdoc_no_newline_at_end.txt"
+    ]
+
+    # These files are either failing to parse or failing to translate, so we'll
+    # skip them for now.
+    skip_all = skip_incorrect | [
+      "dash_heredocs.txt",
+      "dos_endings.txt",
+      "heredocs_with_ignored_newlines.txt",
+      "regex.txt",
+      "regex_char_width.txt",
+      "spanning_heredoc.txt",
+      "spanning_heredoc_newlines.txt",
+      "unescaping.txt"
+    ]
+
+    # Not sure why these files are failing on JRuby, but skipping them for now.
+    if RUBY_ENGINE == "jruby"
+      skip_all.push("emoji_method_calls.txt", "symbols.txt")
+    end
+
+    # These files are failing to translate their lexer output into the lexer
+    # output expected by the parser gem, so we'll skip them for now.
+    skip_tokens = [
+      "comments.txt",
+      "heredoc_with_comment.txt",
+      "indented_file_end.txt",
+      "methods.txt",
+      "strings.txt",
+      "tilde_heredocs.txt",
+      "xstring_with_backslash.txt"
+    ]
+
+    Dir["*.txt", base: base].each do |name|
+      next if skip_all.include?(name)
+
+      define_method("test_#{name}") do
+        assert_equal_parses(File.join(base, name), compare_tokens: !skip_tokens.include?(name))
+      end
+    end
+
+    private
+
+    def assert_equal_parses(filepath, compare_tokens: true)
+      buffer = Parser::Source::Buffer.new(filepath, 1)
+      buffer.source = File.read(filepath)
+
+      parser = Parser::Ruby33.new
+      parser.diagnostics.consumer = ->(*) {}
+      parser.diagnostics.all_errors_are_fatal = true
+
+      expected_ast, expected_comments, expected_tokens =
+        begin
+          parser.tokenize(buffer)
+        rescue ArgumentError, Parser::SyntaxError
+          return
+        end
+
+      actual_ast, actual_comments, actual_tokens =
+        Prism::Translation::Parser33.new.tokenize(buffer)
+
+      assert_equal expected_ast, actual_ast, -> { assert_equal_asts_message(expected_ast, actual_ast) }
+      assert_equal_tokens(expected_tokens, actual_tokens) if compare_tokens
+      assert_equal_comments(expected_comments, actual_comments)
+    end
+
+    def assert_equal_asts_message(expected_ast, actual_ast)
+      queue = [[expected_ast, actual_ast]]
+
+      while (left, right = queue.shift)
+        if left.type != right.type
+          return "expected: #{left.type}\nactual: #{right.type}"
+        end
+
+        if left.location != right.location
+          return "expected:\n#{left.inspect}\n#{left.location.inspect}\nactual:\n#{right.inspect}\n#{right.location.inspect}"
+        end
+
+        if left.type == :str && left.children[0] != right.children[0]
+          return "expected: #{left.inspect}\nactual: #{right.inspect}"
+        end
+
+        left.children.zip(right.children).each do |left_child, right_child|
+          queue << [left_child, right_child] if left_child.is_a?(Parser::AST::Node)
+        end
+      end
+
+      "expected: #{expected_ast.inspect}\nactual: #{actual_ast.inspect}"
+    end
+
+    def assert_equal_tokens(expected_tokens, actual_tokens)
+      if expected_tokens != actual_tokens
+        expected_index = 0
+        actual_index = 0
+
+        while expected_index < expected_tokens.length
+          expected_token = expected_tokens[expected_index]
+          actual_token = actual_tokens[actual_index]
+
+          expected_index += 1
+          actual_index += 1
+
+          # The parser gem always has a space before a string end in list
+          # literals, but we don't. So we'll skip over the space.
+          if expected_token[0] == :tSPACE && actual_token[0] == :tSTRING_END
+            expected_index += 1
+            next
+          end
+
+          # There are a lot of tokens that have very specific meaning according
+          # to the context of the parser. We don't expose that information in
+          # prism, so we need to normalize these tokens a bit.
+          case actual_token[0]
+          when :kDO
+            actual_token[0] = expected_token[0] if %i[kDO_BLOCK kDO_LAMBDA].include?(expected_token[0])
+          when :tLPAREN
+            actual_token[0] = expected_token[0] if expected_token[0] == :tLPAREN2
+          when :tPOW
+            actual_token[0] = expected_token[0] if expected_token[0] == :tDSTAR
+          end
+
+          # Now we can assert that the tokens are actually equal.
+          assert_equal expected_token, actual_token, -> {
+            "expected: #{expected_token.inspect}\n" \
+            "actual: #{actual_token.inspect}"
+          }
+        end
+      end
+    end
+
+    def assert_equal_comments(expected_comments, actual_comments)
+      assert_equal expected_comments, actual_comments, -> {
+        "expected: #{expected_comments.inspect}\n" \
+        "actual: #{actual_comments.inspect}"
+      }
+    end
+  end
+end