Resolve Spring @Value expression in JUnit tests

Question

Here's a snippet of a Spring bean:

@Component
public class Bean {

    @Value("${bean.timeout:60}")
    private Integer timeout;

    // ...
}

Now I want to test this bean with a JUnit test. I'm therefore using the SpringJUnit4ClassRunner and the ContextConfiguration annotation.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration
public class BeanTest {

    @Autowired
    private Bean bean;

    // tests ...

    @Configuration
    public static class SpringConfiguration {
        @Bean
        public Bean bean() {
            return new Bean();
        }
    }
}

Unfortunately the SpringJUnit4ClassRunner can't resolve the @Value expression, even though a default value is supplied (a NumberFormatException is thrown). It seems that the runner isn't even able to parse the expression.

Is something missing in my test?

This looks like similar thread: http://stackoverflow.com/questions/17353327/populating-spring-value-during-unit-test — Ernestas Kardzys, Jan 02 '14 at 09:25

score 19 · Accepted Answer · answered Jan 02 '14 at 09:42

Your test @Configuration class is missing an instance of PropertyPlaceholderConfigurer and that's why Spring does not know how to resolve those expressions; add a bean like the following to your SpringConfiguration class

@org.springframework.context.annotation.Bean
public static PropertyPlaceholderConfigurer propertyPlaceholderConfigurer() {
    PropertyPlaceholderConfigurer ppc = new PropertyPlaceholderConfigurer();
    ppc.setIgnoreResourceNotFound(true);
    return ppc;
}

and move it to a separate class and use

@ContextConfiguration(classes=SpringConfiguration.class)

to be more specific when running your test.

Works also without setting the `PropertyPlaceholderConfigurer` to ignore a not found resource. — Harold L. Brown, Jan 02 '14 at 11:07

Resolve Spring @Value expression in JUnit tests

1 Answers1