spring-boot-demo/src/test/java/com/ankurm/actuator/HealthGroupTests.java

package com.ankurm.actuator;

import com.ankurm.actuator.health.UpstreamState;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.Test;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.health.contributor.Status;
import org.springframework.boot.health.registry.HealthContributorRegistry;
import org.springframework.boot.health.contributor.HealthIndicator;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.ActiveProfiles;

import static org.assertj.core.api.Assertions.assertThat;

/**
 * The contract that matters operationally: an upstream outage must move readiness and must NOT
 * move liveness.
 *
 * <p>See docs/07-groups-and-probes.md.
 */
// DEFINED_PORT, not the default MOCK environment. ExternalApiHealthIndicator makes a real
// HTTP call to this application's own stub controller, so a servlet container has to be
// listening on the port the indicator was configured with. With the mock environment the
// indicator reports DOWN with "Connection refused" and the test proves nothing.
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.DEFINED_PORT)
@ActiveProfiles("groups")
class HealthGroupTests {

    @Autowired
    private HealthContributorRegistry registry;

    @Autowired
    private UpstreamState upstream;

    @AfterEach
    void reset() {
        this.upstream.set(UpstreamState.Mode.UP);
    }

    private Status statusOf(String name) {
        var contributor = this.registry.getContributor(name);
        assertThat(contributor).as("contributor '%s' is registered", name).isNotNull();
        return ((HealthIndicator) contributor).health().getStatus();
    }

    @Test
    void everyCustomIndicatorIsRegisteredUnderTheExpectedName() {
        // The bean name, minus a trailing "HealthIndicator", is the key in the JSON response.
        // Rename the bean and you silently break every dashboard that reads it.
        assertThat(statusOf("ordersDatabase")).isNotNull();
        assertThat(statusOf("externalApi")).isNotNull();
        assertThat(statusOf("kafka")).isNotNull();
    }

    @Test
    void upstreamOutageMovesTheExternalApiIndicatorButNotLiveness() {
        assertThat(statusOf("externalApi")).isEqualTo(Status.UP);
        assertThat(statusOf("livenessState")).isEqualTo(Status.UP);

        this.upstream.set(UpstreamState.Mode.DOWN);

        assertThat(statusOf("externalApi")).isEqualTo(Status.DOWN);
        assertThat(statusOf("livenessState"))
                .as("a third-party outage must never make this process look unrecoverable")
                .isEqualTo(Status.UP);
    }

    @Test
    void theExternalApiIndicatorRespectsItsTimeoutBudget() {
        this.upstream.set(UpstreamState.Mode.SLOW);
        long start = System.nanoTime();
        Status status = statusOf("externalApi");
        long elapsedMs = (System.nanoTime() - start) / 1_000_000;

        assertThat(status).isEqualTo(Status.DOWN);
        // The stub sleeps 30s. demo.upstream.timeout-ms is 750. If this assertion ever fails,
        // someone removed the read timeout and the health endpoint can now block a worker.
        assertThat(elapsedMs).isLessThan(5_000L);
    }
}