1 files changed, 34 insertions, 0 deletions
diff --git a/spec/syntax_suggest/unit/core_ext_spec.rb b/spec/syntax_suggest/unit/core_ext_spec.rb
new file mode 100644
index 0000000000..499c38a240
--- /dev/null
+++ b/spec/syntax_suggest/unit/core_ext_spec.rb
@@ -0,0 +1,34 @@
+require_relative "../spec_helper"
+
+module SyntaxSuggest
+  RSpec.describe "Core extension" do
+    it "SyntaxError monkepatch ensures there is a newline to the end of the file" do
+      skip if Gem::Version.new(RUBY_VERSION) < Gem::Version.new("3.2")
+
+      Dir.mktmpdir do |dir|
+        tmpdir = Pathname(dir)
+        file = tmpdir.join("file.rb")
+        file.write(<<~EOM.strip)
+          print 'no newline
+        EOM
+
+        core_ext_file = lib_dir.join("syntax_suggest").join("core_ext")
+        require_relative core_ext_file
+
+        original_message = "blerg"
+        error = SyntaxError.new(original_message)
+        def error.set_tmp_path_for_testing=(path)
+          @tmp_path_for_testing = path
+        end
+        error.set_tmp_path_for_testing = file
+        def error.path
+          @tmp_path_for_testing
+        end
+
+        detailed = error.detailed_message(highlight: false, syntax_suggest: true)
+        expect(detailed).to include("'no newline\n#{original_message}")
+        expect(detailed).to_not include("print 'no newline#{original_message}")
+      end
+    end
+  end
+end