Spring Dynamic Property

Tools to define a dynamic property in Spring Boot integration tests.

How to set a property value in tests by the standard spring mechanics

In the Spring Framework we have an annotation TestPropertySource which allows define a final property value:

@SpringBootTest
@ExtendWith(SpringExtension.class)
@TestPropertySource(properties = "my.variable=12345")
class FinalPropertyValueTest {

	@Value("${my.variable}")
	private String variable;

	@Test
	void testVariableValue() {
		assertThat(variable).isEqualTo("12345");
	}
}

On this way we have a small limitation - we cannot define a dynamic value of properties in this annotation, even use of a static method not allowed here.

How to define a dynamic value of properties in tests

spring-dynamic-property supports an ability to define a dynamic value of properties and declare static property provider methods in your test class.

All that you need to use the spring-dynamic-property is the next dependency:

<dependency>
    <groupId>com.jupiter-tools</groupId>
    <artifactId>spring-dynamic-property</artifactId>
    <version>0.1</version>
</dependency>

Let’s look at the simple example of using a dynamic value in properties:

Simple example

@SpringBootTest
@ExtendWith(SpringExtension.class)
class SimpleTest {

	@DynamicTestProperty
	private static TestPropertyValues props() {
		return TestPropertyValues
				.of("variable=" + (int) Math.sqrt(64));
	}

	@Value("${variable}")
	private int variable;

	@Test
	void testSqrt() {
		assertThat(variable).isEqualTo(8);
	}
}

Example with the using of TestContainers

A most primary case to use dynamic properties is a TestContainers initialization in your spring-boot applications.

Let’s consider an example of initialization standard spring-boot properties after start Redis test container:

@SpringBootTest
@Testcontainers
@ExtendWith(SpringExtension.class)
class RedisTestcontainersTest {

    private static final Integer REDIS_PORT = 6379;

    @Container
    private static GenericContainer redis = new GenericContainer("redis:latest")
            .withExposedPorts(REDIS_PORT);

    @DynamicTestProperty
    private static TestPropertyValues props() {
        return TestPropertyValues.of("spring.redis.host=" + redis.getContainerIpAddress(),
                                     "spring.redis.port=" + redis.getMappedPort(REDIS_PORT));
    }

    @Autowired
    private RedisTemplate redisTemplate;

    @Test
    void readWriteValueByRedisTemplate() {
        String key = "test";
        String value = "sabracadabra";
        // Act
        redisTemplate.opsForValue().set(key, value);
        // Assert
        assertThat(redisTemplate.opsForValue().get(key)).isEqualTo(value);
    }
}

Include dynamic property in meta-annotations

If you need to make you own annotation with dynamic property declaration then you can specify a file with @DynamicProperty methods by the using of @IncludeDynamicProperty annotation as you can see in the example below:

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@IncludeDynamicProperty(DynamicPropertyHolder.class)
public @interface AnnotationWithDynamicProperty {

}

the file with dynamic properties:

public class DynamicPropertyHolder {

    @DynamicTestProperty
    private static TestPropertyValues property(){
        return TestPropertyValues.of("key=12345");
    }
}

and now you can use this annotation in your tests to set this property:

@SpringBootTest
@AnnotationWithDynamicProperty
class MetaAnnotationTest {

    @Value("${key}")
    private String key;

    @Test
    void checkPropertyValueInjectInAnnotation() {
        assertThat(key).isEqualTo("12345");
    }
}