spring-boot unit testing get application properties

Question

I'm new to spring-boot, currently trying to develop a kafka producer I want to test method that use value define in properties file. but it show value is null how solve this.I have added my property files to separate resource file in test folder also this is my folder structure

@SpringBootTest
public class KafkaProducerImplTest {
 @BeforeEach
 void setUp() {
 }
 @Test
 void check() {
 KafkaProducerImpl kpi = new KafkaProducerImpl();
 kpi.check();
 }
 }
 
 @Service
 public class KafkaProducerImpl implements KafkaProducerInterface
 {
 @Value("${kafka.brokers.local}")
 private String kafkaBrokers;
 @Value("${schema-registry}")
 private String schemaRegistry;
 private Properties config()
 {
 Properties props = new Properties();
 props.setProperty("bootstrap.servers",kafkaBrokers);
 props.setProperty("acks", "1");
 props.setProperty("reties", "10");
 props.setProperty("key.serializer", StringSerializer.class.getName()); 
 props.setProperty("value.serializer",Serializer.class.getName());
 props.setProperty("schema.registry.url",schemaRegistry);
 return props;
 }
 public <K,T>KafkaProducer<K,T> getProducer()
 {
 return new KafkaProducer<>(config());
 }
 public <T>ProducerRecord createRecord(String Topic,T msg)
 {
 return new ProducerRecord<>(
 Topic,msg
 );
 }
 public void sendMessage(KafkaProducer producer,ProducerRecord record)
 {
 producer.send(record, (recordMetadata, e) -> {
 if (e == null){
 System.out.println("success");
 }
 });
 producer.flush();
 }
 public void closeProducer(KafkaProducer producer){
 producer.close();
 }
 public void check(){
 System.out.println(schemaRegistry);
 }
}

• M. Deinum: You are creating a new instance yourself instead of getting the Spring managed KafkaProducerImpl instance.
• Damitha Dayananda: ok how can i take spring managed instance.because when i try get instance through @Autowired it gives error
• M. Deinum: You should autowired the KafkaProducerInterface instead of the Impl and your test needs @RunWith(SpringRunner.class).

Answer 1

finally i find way, thanks everyone helping me.

@RunWith(SpringRunner.class)
@SpringBootTest
public class KafkaProducerImplTest {
@Autowired
private KafkaProducerInterface kpi;
@Test
public void check() {
 kpi.check(); 
}

}

• Aditya Narayan Dixit: Not different from the answer I posted. :)

Answer 2

Annotate you test class with @RunWith(SpringRunner.class) which will load application context for you and instantiate the spring beans. To add spring boot support add @SpringBootTest(Which you already have).

You'll have to remove this line

"KafkaProducerImpl kpi = new KafkaProducerImpl();" 

and autowire using interface reference instead. Something like this:

@Autowired
KafkaProducerInterface kpi;

I'm assuming you have the properties used here(ex. "kafka.brokers.local") defined in your test properties file.

• Damitha Dayananda: i have change my code as you said now i get, java.lang.NullPointerException