How to enable Spring's auto-configuration report in tests?

Question

I just found out that Spring has a debug mode, which gives insights on the auto-configuration. For a server, it can be enabled by passing --debug as an application parameter.

Is there a way to enable the debug mode also for tests (executed with the SpringJUnit4ClassRunner)?

---

If the auto-configuration report is working, it should print some output like this:

=========================
AUTO-CONFIGURATION REPORT
=========================


Positive matches:
-----------------

   ConfigServiceBootstrapConfiguration#configServicePropertySource matched
      - matched (OnPropertyCondition)

   ConfigurationPropertiesRebinderAutoConfiguration matched
      - @ConditionalOnBean (types: org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor; SearchStrategy: all) found the following [org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor] (OnBeanCondition)

   ConfigurationPropertiesRebinderAutoConfiguration#configurationPropertiesBeans matched
      - @ConditionalOnMissingBean (types: org.springframework.cloud.context.properties.ConfigurationPropertiesBeans; SearchStrategy: current) found no beans (OnBeanCondition)

   ConfigurationPropertiesRebinderAutoConfiguration#configurationPropertiesRebinder matched
      - @ConditionalOnMissingBean (types: org.springframework.cloud.context.properties.ConfigurationPropertiesRebinder; SearchStrategy: current) found no beans (OnBeanCondition)

   EncryptionBootstrapConfiguration matched
      - @ConditionalOnClass classes found: org.springframework.security.crypto.encrypt.TextEncryptor (OnClassCondition)

   PropertyPlaceholderAutoConfiguration#propertySourcesPlaceholderConfigurer matched
      - @ConditionalOnMissingBean (types: org.springframework.context.support.PropertySourcesPlaceholderConfigurer; SearchStrategy: current) found no beans (OnBeanCondition)


Negative matches:
-----------------

   ConfigServiceBootstrapConfiguration.RetryConfiguration did not match
      - required @ConditionalOnClass classes not found: org.springframework.retry.annotation.Retryable,org.aspectj.lang.annotation.Aspect (OnClassCondition)

   DiscoveryClientConfigServiceBootstrapConfiguration did not match
      - @ConditionalOnProperty missing required properties spring.cloud.config.discovery.enabled (OnPropertyCondition)

   EncryptionBootstrapConfiguration.RsaEncryptionConfiguration did not match
      - @ConditionalOnClass classes found: org.springframework.security.rsa.crypto.RsaSecretEncryptor (OnClassCondition)
      - Keystore nor key found in Environment (EncryptionBootstrapConfiguration.KeyCondition)

   EncryptionBootstrapConfiguration.VanillaEncryptionConfiguration did not match
      - required @ConditionalOnMissing classes found: org.springframework.security.rsa.crypto.RsaSecretEncryptor (OnClassCondition)

   EurekaDiscoveryClientConfigServiceBootstrapConfiguration did not match
      - @ConditionalOnClass classes found: org.springframework.cloud.config.client.ConfigServicePropertySourceLocator (OnClassCondition)
      - @ConditionalOnProperty missing required properties spring.cloud.config.discovery.enabled (OnPropertyCondition)


Exclusions:
-----------

    None


Unconditional classes:
----------------------

    None

Answer 1

--debug sets a debug property which then switches on the auto-configuration report. You can do the same in your test using, for example, @TestPropertySource on your test class:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(Application.class)
@TestPropertySource(properties = "debug=true")
public class YourTests {
    // …
}