### Question:
SpelAttributeConverter implements AttributeConverter<Expression, String> { @Override public String convertToDatabaseColumn(Expression expression) { if (expression == null) { return ""; } return expression.getExpressionString(); }  @Override String convertToDatabaseColumn(Expression expression); @Override Expression convertToEntityAttribute(String s);  }### Answer:
@Test public void shouldConvertToDatabaseColumn() { ExpressionParser expressionParser = new SpelDeserializer().getElParser(); String expected = "true && true"; Expression expr = expressionParser.parseExpression(expected); assertEquals(expected, attributeConverter.convertToDatabaseColumn(expr)); }