function testTreeUnaffected() {
  var treeBefore =
      'project()\n' +
      '-join(type: inner, impl: hash, join_pred(TableC.id eq TableB.id))\n' +
      '--table_access(TableC)\n' +
      '--select(value_pred(TableB.id gt 100))\n' +
      '---table_access(TableB)\n';

  lf.testing.treeutil.assertTreeTransformation(
      constructTree3(), treeBefore, treeBefore, pass);
}
Tests a simple tree, where
 - Only one join predicate exists.
 - Only the column of the right table has an index, but there is a SelectStep
   after the table access.
Ensures that index join optimization is not applied in this case.