@Test
public void testVariableMapperImpl() {

    ValueExpression expression = createMock(ValueExpression.class);
    replay(resolver, expression);
    VariableMapper variableMapper = context.getVariableMapper();
    assertNull(variableMapper.resolveVariable("whatever"));
    variableMapper.setVariable("var", expression);
    assertEquals(expression, variableMapper.resolveVariable("var"));
    verify(resolver, expression);
}