SpringBootTest - how to assert context not loads and change properties at test level?

Question

I rely on @SpringBootTest heavily when testing application configuration. App properties can be complex, having default values and non-trivial validations. For example:

prop:
  ports: 1205,2303,4039
  fqdn: ${server.host}:${ports[0]}/${path}

@Configuration
SomeConfigClass{
   @Value{"${ports}:{#collections.emptyList}"}
   List<Integer> ports;

   ...
}

When testing such apps, I bring up a full or partial application context without mocks, as there is complexity in the context and validation itself - mocks don't capture this. Unfortunately, there are two limitations I keep finding with this pattern:

How can we test that bad configurations fail to load?

Imagine testing that the port in invalid because it is not on the restricted range of 500 - 1500.
```
@SpringBootTest(
        classes = {SomeConfigClass.class},
        properties = "port=9000"
)
public class BadConfigTest{

    @Test(expected = ApplicationContextFailedException.class)
    public void WHEN_port_9000_THEN_appcontext_fails_to_load() {}

}
```
Since the test framework loads after the application context, there appears to be no way to test that an app context fails to load. For now I actually write the tests, manually confirm they fail, and then annotation with @Ignored so they are not lost.
How to change properties at the test method, rather than class, level?

@SpringBootTest is a class annotation, meaning application properties are bound at the test-class level. This results in needing a test class for many sets of properties and bloats the test suite. For example, I'll end up with test classes like:
```
ConfigPropertiesAllValidTest
ConfigPropertiesNoneSetTest
ConfigPropertiesSomeValidSomeNotTest
```
Where each of these only has one or two test cases. Preferably, there'd be a single ConfigPropertiesTest class with different props for each test. Is this possible?

Again - I want to avoid mocks as they don't capture the non-trivial context autoconfiguration performed by Spring at runtime.

Adam Hughes · Accepted Answer · 2019-05-12 17:47:09Z

4

We ended up using the ApplicationContextRunner described in this document:

https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-developing-auto-configuration.html#boot-features-test-autoconfig

answered May 12, 2019 at 17:47

Adam Hughes

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1 Comment

luke Over a year ago

Adam - Thank you for your question (it is very well written) and your own answer to your question :) It helped me a lot. For people searching for information about ApplicationContext testing there is also article/guide about ApplicationContextRunner baeldung.com/spring-boot-context-runner and there are also AssertableWebApplicationContext and AssertableReactiveWebApplicationContext classes which might be helpful when testing web application context. It is also worth to mention that ApplicationContextRunner is available since 2.0.0 version of spring-boot-test.

pcoates · Accepted Answer · 2019-01-21 00:01:45Z

You can use the @ActiveProfiles annotation along with the @SpringBootTest annotation to load properties for different profiles. This is class level, so will only help for case 1 of your question.

@SpringBootTest(classes = {SomeConfigClass.class})
@ActiveProfiles("badconfigtest")
public class BadConfigTest{
    ...
}

Then have an application-badconfigtest.properties with your bad config.

I don't think you'll find a way of changing properties between test methods in the same class. You can use @DirtiesContext to reload the application context, but I've not seen a way to use different property files. I guess you could inject the values into the config classes that have already loaded the properties.

Thanks - I have used the @ActiveProfiles annotation but it doesn't really make much difference because it still forces me to tie one set of properties to a test class

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