Package org.springframework.test.context

Interface DynamicPropertyRegistrar

Functional Interface:
This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
@FunctionalInterface public interface DynamicPropertyRegistrar
Registrar that is used to add properties with dynamically resolved values to the Environment via a DynamicPropertyRegistry.

Any bean in a test's ApplicationContext that implements the DynamicPropertyRegistrar interface will be automatically detected and eagerly initialized before the singleton pre-instantiation phase, and the accept(org.springframework.test.context.DynamicPropertyRegistry) methods of such beans will be invoked with a DynamicPropertyRegistry that performs the actual dynamic property registration on behalf of the registrar.

This is an alternative to implementing @DynamicPropertySource methods in integration test classes and supports additional use cases that are not possible with a @DynamicPropertySource method. For example, since a DynamicPropertyRegistrar is itself a bean in the ApplicationContext, it can interact with other beans in the context and register dynamic properties that are sourced from those beans. Note, however, that any interaction with other beans results in eager initialization of those other beans and their dependencies.

Precedence

Dynamic properties have higher precedence than those loaded from @TestPropertySource, the operating system's environment, Java system properties, or property sources added by the application declaratively by using @PropertySource or programmatically. Thus, dynamic properties can be used to selectively override properties loaded via @TestPropertySource, system property sources, and application property sources.

Example

The following example demonstrates how to implement a DynamicPropertyRegistrar as a lambda expression that registers a dynamic property for the ApiServer bean. Other beans in the ApplicationContext can access the api.url property which is dynamically retrieved from the ApiServer bean — for example, via @Value("${api.url}"). 

 @Configuration
 class TestConfig {

     @Bean
     ApiServer apiServer() {
         return new ApiServer();
     }

     @Bean
     DynamicPropertyRegistrar apiPropertiesRegistrar(ApiServer apiServer) {
         return registry -> registry.add("api.url", apiServer::getUrl);
     }

 }
Since:
6.2
Author:
Sam Brannen
See Also:

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    accept(DynamicPropertyRegistry registry)
    Register dynamic properties in the supplied registry.

  • Method Details