1 files changed, 115 insertions, 0 deletions
diff --git a/test/prism/encoding/regular_expression_encoding_test.rb b/test/prism/encoding/regular_expression_encoding_test.rb
new file mode 100644
index 0000000000..fdff1e3281
--- /dev/null
+++ b/test/prism/encoding/regular_expression_encoding_test.rb
@@ -0,0 +1,115 @@
+# frozen_string_literal: true
+
+return unless defined?(RubyVM::InstructionSequence)
+return if RubyVM::InstructionSequence.compile("").to_a[4][:parser] == :prism
+return if RUBY_VERSION < "3.2"
+
+require_relative "../test_helper"
+
+module Prism
+  class RegularExpressionEncodingTest < TestCase
+    each_encoding do |encoding, _|
+      define_method(:"test_regular_expression_encoding_flags_#{encoding.name}") do
+        assert_regular_expression_encoding_flags(encoding, ["/a/", "/ą/", "//"])
+      end
+
+      escapes = ["\\x00", "\\x7F", "\\x80", "\\xFF", "\\u{00}", "\\u{7F}", "\\u{80}", "\\M-\\C-?"]
+      escapes = escapes.concat(escapes.product(escapes).map(&:join))
+
+      define_method(:"test_regular_expression_escape_encoding_flags_#{encoding.name}") do
+        assert_regular_expression_encoding_flags(encoding, escapes.map { |e| "/#{e}/" })
+      end
+
+      ["n", "u", "e", "s"].each do |modifier|
+        define_method(:"test_regular_expression_encoding_modifiers_/#{modifier}_#{encoding.name}") do
+          regexp_sources = ["abc", "garçon", "\\x80", "gar\\xC3\\xA7on", "gar\\u{E7}on", "abc\\u{FFFFFF}", "\\x80\\u{80}", "\\p{L}" ]
+
+          assert_regular_expression_encoding_flags(
+            encoding,
+            regexp_sources.product(["n", "u", "e", "s"]).map { |r, modifier| "/#{r}/#{modifier}" }
+          )
+        end
+      end
+    end
+
+    private
+
+    def assert_regular_expression_encoding_flags(encoding, regexps)
+      regexps.each do |regexp|
+        source = "# encoding: #{encoding.name}\n#{regexp}"
+
+        encoding_errors = [
+          "invalid multibyte char", "escaped non ASCII character in UTF-8 regexp",
+          "differs from source encoding", "incompatible character encoding",
+          "invalid multibyte escape", "UTF-8 character in non UTF-8 regexp",
+          "invalid Unicode range", "non escaped non ASCII character",
+          "invalid character property name", "invalid Unicode list",
+        ]
+
+        expected =
+          begin
+            eval(source).encoding
+          rescue SyntaxError => error
+            if encoding_errors.find { |e| error.message.include?(e) }
+              error.message.split("\n").map { |m| m[/: (.+?)$/, 1] }
+            else
+              raise
+            end
+          end
+
+        actual =
+          Prism.parse(source).then do |result|
+            if result.success?
+              regexp = result.statement
+
+              actual_encoding = if regexp.forced_utf8_encoding?
+                Encoding::UTF_8
+              elsif regexp.forced_binary_encoding?
+                Encoding::ASCII_8BIT
+              elsif regexp.forced_us_ascii_encoding?
+                Encoding::US_ASCII
+              elsif regexp.ascii_8bit?
+                Encoding::ASCII_8BIT
+              elsif regexp.utf_8?
+                Encoding::UTF_8
+              elsif regexp.euc_jp?
+                Encoding::EUC_JP
+              elsif regexp.windows_31j?
+                Encoding::Windows_31J
+              else
+                encoding
+              end
+
+              if regexp.utf_8? && actual_encoding != Encoding::UTF_8
+                raise "expected regexp encoding to be UTF-8 due to '/u' modifier, but got #{actual_encoding.name}"
+              elsif regexp.ascii_8bit? && (actual_encoding != Encoding::ASCII_8BIT && actual_encoding != Encoding::US_ASCII)
+                raise "expected regexp encoding to be ASCII-8BIT or US-ASCII due to '/n' modifier, but got #{actual_encoding.name}"
+              elsif regexp.euc_jp? && actual_encoding != Encoding::EUC_JP
+                raise "expected regexp encoding to be EUC-JP due to '/e' modifier, but got #{actual_encoding.name}"
+              elsif regexp.windows_31j? && actual_encoding != Encoding::Windows_31J
+                raise "expected regexp encoding to be Windows-31J due to '/s' modifier, but got #{actual_encoding.name}"
+              end
+
+              if regexp.utf_8? && regexp.forced_utf8_encoding?
+                raise "the forced_utf8 flag should not be set when the UTF-8 modifier (/u) is used"
+              elsif regexp.ascii_8bit? && regexp.forced_binary_encoding?
+                raise "the forced_ascii_8bit flag should not be set when the UTF-8 modifier (/u) is used"
+              end
+
+              actual_encoding
+            else
+              errors = result.errors.map(&:message)
+
+              if errors.last&.include?("UTF-8 mixed within")
+                nil
+              else
+                errors
+              end
+            end
+          end
+
+        assert_equal expected, actual
+      end
+    end
+  end
+end