public function testAssemble()
 {
     $expression = new IncrementExpression();
     $expression->setField(FieldExpression::create('new_field'));
     $this->assertEquals('new_field + 0', QueryAssembler::stringify($expression));
     $expression->setIncrementValue('abc');
     $this->assertEquals('new_field + 0', QueryAssembler::stringify($expression));
     $expression->setIncrementValue('1');
     $this->assertEquals('new_field + 1', QueryAssembler::stringify($expression));
     $expression->setIncrementValue(1);
     $this->assertEquals('new_field + 1', QueryAssembler::stringify($expression));
     $stmt = QueryBuilder::update('tbl');
     $stmt->set('inc_field', $expression);
     $qa = new QueryAssembler($stmt);
     $this->assertEquals('UPDATE tbl SET inc_field = new_field + ?', $qa->getQuery());
     $this->assertEquals([1], $qa->getParameters());
 }