Chore: Fix test failure due to missing API from mock

I started using `engine.on` to listen for `parse::html::end`. Since this
wasn't in the mock for `t.context.engine` one of the early tests
failed (and the rest generated the error `'Attempted to wrap default
which is already wrapped'` since the test didn't clean up.

packages/connector-local/tests/tests.ts

@@ -23,7 +23,8 @@ test.beforeEach((t) => {
         clean() { },
         clear() { },
         emitAsync() { },
-        notify() { }
+        notify() { },
+        on() { }
     };
     t.context.isFile = isFile;
 });