TestCustomConversionService.java

package hack;

import java.time.Duration;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Lazy;
import org.springframework.core.convert.ConversionService;
import org.springframework.core.convert.support.ConfigurableConversionService;
import org.springframework.core.env.ConfigurableEnvironment;
import org.springframework.core.env.Environment;
import org.springframework.core.env.PropertyResolver;
import org.springframework.format.datetime.standard.DateTimeFormatterRegistrar;
import org.springframework.format.support.DefaultFormattingConversionService;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.TestPropertySource;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@ContextConfiguration(classes=TestCustomConversionService.Config.class)
@TestPropertySource(properties="dur=PT10s")
public class TestCustomConversionService {
    @Autowired
    Config config;

    @Autowired
    BeanFactory bf;

    @Autowired
    Environment env;

    @Autowired
    PropertyResolver pr;

    // Works, uses our custom conversion service
    @Test
    public void testInject() {
        bf.getBean(Duration.class);
    }

    // No go, doesn't use our conversionService
    @Test
    public void testEnvironment() {
        env.getProperty("dur", Duration.class);
    }

    // No go, doesn't use our conversionService
    @Test
    public void testPropertyResolver() {
        pr.getProperty("dur", Duration.class);
    }

    // But this works
    @Test
    public void testEnvironmentHackFix() {
        ((ConfigurableEnvironment) env).setConversionService((ConfigurableConversionService) Config.conversionService());
        env.getProperty("dur", Duration.class);
    }

    // And so does this
    @Test
    public void testPropertyResolverHackFix() {
        ((ConfigurableEnvironment) env).setConversionService((ConfigurableConversionService) Config.conversionService());
        pr.getProperty("dur", Duration.class);
    }

    @Configuration
    static class Config {
        @Bean
        @Lazy
        Duration convertDuration(@Value("PT20s") Duration duration) {
            return duration;
        }

        @Bean
        static ConversionService conversionService() {
            DefaultFormattingConversionService cs = new DefaultFormattingConversionService();
            new DateTimeFormatterRegistrar().registerFormatters(cs);
            return cs;
        }
    }
}

TestDefaultConversionService.java

package hack;

import java.time.Duration;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Lazy;
import org.springframework.core.env.Environment;
import org.springframework.core.env.PropertyResolver;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.TestPropertySource;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@ContextConfiguration(classes=TestDefaultConversionService.Config.class)
@TestPropertySource(properties="dur=PT10s")
public class TestDefaultConversionService {
    @Autowired
    Config config;

    @Autowired
    BeanFactory bf;

    @Autowired
    Environment env;

    @Autowired
    PropertyResolver pr;

    // All three of these fail due to not knowing Duration type

    @Test
    public void testInject() {
        bf.getBean(Duration.class);
    }

    @Test
    public void testEnvironment() {
        env.getProperty("dur", Duration.class);
    }

    @Test
    public void testPropertyResolver() {
        pr.getProperty("dur", Duration.class);
    }

    @Configuration
    static class Config {
        @Bean
        @Lazy
        Duration convertDuration(@Value("PT20s") Duration duration) {
            return duration;
        }
    }
}