Question

In Guice, I have a ProductionModule with my bindings. In my tests, I can load that PLUS a module that overrides a few of the production bindings with mock objects. How do I do such a thing in spring….

For example, load production-spring.xml in test files and then have the test load in test-spring.xml which would ONLY override some of the bindings in production-spring.xml

This tests the integration and make sure changes in production-spring.xml don’t break things. These are more automated integration tests then testing a unit and work extremely well.

Answer 1

You can override beans by listing multiple xml files. Beans in the later files will override those loaded before.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(
      locations = {"classpath:prodDB.xml", 
                   "classpath:applicationContext.xml", 
                   "classpath:testDb.xml"})
public class SpringTest {

    @Autowired
    protected DataSource dataSource; //uses the datasource from testDb.xml

}

So in this case testDB.xml overrides the DataSource configured in prodDb.xml. This applies even if you don’t use the SpringJUnit4ClassRunner as well:

new ClassPathXmlApplicationContext(new String[]
        {"classpath:prodDb.xml",
         "classpath:testDb.xml"});

Using a tool like Constretto you can do the same with annotated beans:

@Service
public class FooService...

@Service
@Environment("test")
public class FakeFooService ...

Now, if you run a test with the @Environment("test") annotation on the class, the FakeFooService will be used.