@Override
  public void copyVariablesFrom( VariableSpace space ) {
    variables.copyVariablesFrom( space );
  }
@Test
  public void testCopyVariablesFrom() {
    assertNull( meta.getVariable( "var1" ) );
    VariableSpace vars = mock( VariableSpace.class );
    when( vars.getVariable( "var1" ) ).thenReturn( "x" );
    when( vars.listVariables() ).thenReturn( new String[]{ "var1" } );
    meta.copyVariablesFrom( vars );
    assertEquals( "x", meta.getVariable( "var1", "y" ) );
  }