How to use dependency-injection with SpringBootTest

Question

I have an application that uses SpringBoot for dependency injection and the app works fine, but testing fails because @Autowired fields aren't being injected during tests.

@SpringBootApplication public class ProcessorInterface { protected final static Logger logger = Logger.getLogger( ProcessorInterface.class ); public static void main(String[] args) { try { SpringApplication.run(ProcessorInterfaceRunner.class, args); } catch (Exception ex) { logger.error("Error running ProcessorInterface", ex); } } } @Component @Configuration @ComponentScan public class ProcessorInterfaceRunner implements CommandLineRunner { protected final static Logger logger = Logger.getLogger( ProcessorInterface.class ); @Autowired private RequestService requestService = null; @Autowired private ValidatorService validatorService = null; @Override public void run(String... args) throws Exception { ESPOutTransaction outTransaction = null; outTransaction = new ESPOutTransaction(); // initialize outTransaction fields ... // done initializing outTransaction fields if (validatorService.isValid(outTransaction)) { System.out.println(requestService.getRequest(outTransaction)); } else { System.out.println("Bad Data"); } } } @Service public class ESPRequestService implements RequestService<ESPOutTransaction> { @Autowired ValidatorService validatorService = null; @Override public String getRequest(ESPOutTransaction outTransaction) throws IllegalArgumentException { if (!validatorService.isValid(outTransaction)) { throw new IllegalArgumentException("Invalid parameters in transaction object. " + outTransaction.toString()); } StringBuffer buff = new StringBuffer("create request XML"); buff.append("more XML"); return buff.toString(); } } @Service public class ESPValidatorService implements ValidatorService { private static org.apache.log4j.Logger logger = Logger.getLogger(ESPValidatorService.class); // declare some constants for rules private static final int MAX_LENGTH_XYZ = 3; @Override public boolean isValid(OutTransaction outTransaction) { ESPOutTransaction espOutTransaction = (ESPOutTransaction)outTransaction; boolean isValid = true; if (espOutTransaction == null) { logger.warn("espOutTransaction is NULL"); isValid = false; } else { // XYZ is required if (espOutTransaction.getXYZ() == null) { logger.warn("XYZis NULL\r\n" + espOutTransaction.toString()); isValid = false; } // XYZ max length = MAX_LENGTH_XYZ if (espOutTransaction.getXYZ() != null && espOutTransaction.getPubCode().trim().length() > MAX_LENGTH_XYZ) { logger.warn("XYZis too long (max length " + MAX_LENGTH_XYZ + ")\r\n" + espOutTransaction.toString()); isValid = false; } } return isValid; } }

These all work and I get good output when I run the app. When I try to test it though, it fails because it can't find ESPValidatorService to inject into ESPRequestService

@RunWith(Suite.class) @SuiteClasses({ ESPOutTransactionValidatorTest.class, ESPRequestTest.class }) public class AllTests {} @RunWith(SpringRunner.class) @SpringBootTest(classes = {ESPRequestService.class}) public class ESPRequestTest { @Test public void testGetRequest() { ESPRequestService requestService = new ESPRequestService(); String XYZ = "XYZ"; ESPOutTransaction outTransaction = null; outTransaction = new ESPOutTransaction(); outTransaction.setXYZ(XYZ); String strRequest = "some expected request XML"; String request = requestService.getRequest(outTransaction); assertEquals(request, strRequest); } } @RunWith(SpringRunner.class) @SpringBootTest(classes = ESPValidatorService.class) public class ESPOutTransactionValidatorTest { @Test public void testIsValid() { ESPValidatorService validatorService = new ESPValidatorService(); ESPOutTransaction outTransaction = null; // test request = null assertFalse(validatorService.isValid(outTransaction)); String XYZ = "XYZ"; outTransaction = new ESPOutTransaction(); outTransaction.setXYZ(XYZ); // test all good assertTrue(validatorService.isValid(outTransaction)); // test XYZ outTransaction.setXYZ(null); assertFalse(validatorService.isValid(outTransaction)); outTransaction.setXYZ("ABCD"); // too long assertFalse(validatorService.isValid(outTransaction)); outTransaction.setXYZ(XYZ); } }

How can I get the unit tests to auto wire?

davidxxx · Accepted Answer · 2017-11-30 22:25:15Z

I see two problems :

1) you don't rely on Spring beans but you create instances with the new operator.

Instead of writing :

ESPRequestService requestService = new ESPRequestService();

you should let Spring inject the instance :

@Bean ESPRequestService requestService;

2) The @SpringBootTest configuration is not correct.

In each test, you specified a very specific bean class in the classes attribute of @SpringBootTest :

@SpringBootTest(classes = ESPValidatorService.class) public class ESPOutTransactionValidatorTest {

and

@SpringBootTest(classes = {ESPRequestService.class}) public class ESPRequestTest {

But classes attributes of @SpringBootTest serves to specify the annotated classes to use for loading an ApplicationContext.

The annotated classes to use for loading an ApplicationContext. Can also be specified using @ContextConfiguration(classes=...). If no explicit classes are defined the test will look for nested @Configuration classes, before falling back to a SpringBootConfiguration search.

So all configuration classes and beans of your application may not be discovered and loaded in the Spring container .

To be able to load all application beans during your tests, the most simple way is not specifying the classes attribute in the @SpringBootTest annotation :

@SpringBootTest public class ESPRequestTest { ...}

It will look for a Spring bean that holds the @SpringBootConfiguration.
Ideally, it will found the @SpringBootApplication bean of your application.
If the package of the test class is located inside the package (or at a lower level) of the @SpringBootApplication class, it should be automatically discovered.

Otherwise the other way is specifying a configuration that will allow to load all required beans :

@SpringBootTest(classes = MySpringBootApplication.class) public class ESPRequestTest { ...}

This wasn't the only problem I had, but it got me pointed in the right direction.

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