public Set<Analysis.AliasedDataSource> extractDataSources(final AstNode node) {
    new Visitor().process(node, null);
    return getAllSources();
  }
@Test
  public void shouldHandleAliasedJoinDataSources() {
    // Given:
    final AstNode stmt = givenQuery("SELECT * FROM TEST1 t1 JOIN TEST2 t2"
        + " ON test1.col1 = test2.col1;");

    // When:
    extractor.extractDataSources(stmt);

    // Then:
    assertContainsAlias(T1, T2);
  }