[ffigen] Add description to typedef test (#557)

pkgs/ffigen/test/header_parser_tests/expected_bindings/_expected_typedef_bindings.dart

diff --git a/pkgs/ffigen/test/header_parser_tests/expected_bindings/_expected_typedef_bindings.dart b/pkgs/ffigen/test/header_parser_tests/expected_bindings/_expected_typedef_bindings.dart
index b880746..885f641 100644
--- a/pkgs/ffigen/test/header_parser_tests/expected_bindings/_expected_typedef_bindings.dart
+++ b/pkgs/ffigen/test/header_parser_tests/expected_bindings/_expected_typedef_bindings.dart
@@ -6,6 +6,7 @@
 // ignore_for_file: type=lint
 import 'dart:ffi' as ffi;
 
+/// Typedef Test
 class Bindings {
   /// Holds the symbol lookup function.
   final ffi.Pointer<T> Function<T extends ffi.NativeType>(String symbolName)

pkgs/ffigen/test/header_parser_tests/typedef_test.dart

diff --git a/pkgs/ffigen/test/header_parser_tests/typedef_test.dart b/pkgs/ffigen/test/header_parser_tests/typedef_test.dart
index 51b90e6..5c373f5 100644
--- a/pkgs/ffigen/test/header_parser_tests/typedef_test.dart
+++ b/pkgs/ffigen/test/header_parser_tests/typedef_test.dart
@@ -19,6 +19,7 @@
       actual = parser.parse(
         testConfig('''
 ${strings.name}: 'Bindings'
+${strings.description}: 'Typedef Test'
 ${strings.output}: 'unused'
 
 ${strings.headers}: