Quick try-out of property resolution in Spring tests. As it turned out there was an application.properties in src/test/resources which was masking the one in src/main. @Autowiring the ApplicationContext enables browsing the contents in a debugger to see what's going on.

Probeersel.java

package testing;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.PropertySource;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.TestPropertySource;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import static org.junit.Assert.assertNotNull;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = Probeersel.class)
@PropertySource("classpath:application.properties")
public class Probeersel {

    @Value("${offer.fiber.postcodes.csv}")
    String filename;

    @Bean
    public GetSet one() {
        return new GetSet("one", null);
    }

    @Bean
    public GetSet two(GetSet one, @Value("${offer.fiber.postcodes.csv:fallback}") String value) {
        GetSet second = new GetSet("TWO", one);
//        second.setValue(value);
        return second;
    }

    @Autowired
    GetSet two;

    @Autowired
    ApplicationContext applicationContext;

    @Test
    public void testOne() {
        assertNotNull(filename);
        System.out.println(filename);
        System.out.println(two);
    }

    class GetSet {
        private String name;
        private GetSet inner;
        @Value("${offer.fiber.postcodes.csv:default value}")
        String value;

        public GetSet(String name, GetSet inner) {
            this.name = name;
            this.inner = inner;
        }

        public void setValue(String value) {
            this.value = value;
        }

        @Override
        public String toString() {
            return "GetSet{" +
                    "name='" + name + '\'' +
                    ", inner=" + inner +
                    ", value=" + value +
                    '}';
        }
    }
}