circuit-breaker/src/test/java/com/iluwatar/circuitbreaker/AppTest.java - master - githubmirror/java-design-patterns

circuit-breaker/src/test/java/com/iluwatar/circuitbreaker/AppTest.java
134 строки6 KB
Ilkka Seppälä
deps: Refactor dependencies (#3224)
29 мар 2025, 20:34
29 мар 2025, 20:340ca162a
/*
 * This project is licensed under the MIT license. Module model-view-viewmodel is using ZK framework licensed under LGPL (see lgpl-3.0.txt).
 *
 * The MIT License
 * Copyright © 2014-2022 Ilkka Seppälä
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package com.iluwatar.circuitbreaker;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/** App Test showing usage of circuit breaker. */
class AppTest {

  private static final Logger LOGGER = LoggerFactory.getLogger(AppTest.class);

  // Startup delay for delayed service (in seconds)
  private static final int STARTUP_DELAY = 4;

  // Number of failed requests for circuit breaker to open
  private static final int FAILURE_THRESHOLD = 1;

  // Time period in seconds for circuit breaker to retry service
  private static final int RETRY_PERIOD = 2;

  private MonitoringService monitoringService;

  private CircuitBreaker delayedServiceCircuitBreaker;

  private CircuitBreaker quickServiceCircuitBreaker;

  /**
   * Set up the circuit breakers and services, where {@link DelayedRemoteService} will be start with
   * a delay of 4 seconds and a {@link QuickRemoteService} responding healthy. Both services are
   * wrapped in a {@link DefaultCircuitBreaker} implementation with failure threshold of 1 failure
   * and retry time period of 2 seconds.
   */
  @BeforeEach
  void setupCircuitBreakers() {
    var delayedService = new DelayedRemoteService(System.nanoTime(), STARTUP_DELAY);
    // Set the circuit Breaker parameters
    delayedServiceCircuitBreaker =
        new DefaultCircuitBreaker(
            delayedService, 3000, FAILURE_THRESHOLD, RETRY_PERIOD * 1000 * 1000 * 1000);

    var quickService = new QuickRemoteService();
    // Set the circuit Breaker parameters
    quickServiceCircuitBreaker =
        new DefaultCircuitBreaker(
            quickService, 3000, FAILURE_THRESHOLD, RETRY_PERIOD * 1000 * 1000 * 1000);

    monitoringService =
        new MonitoringService(delayedServiceCircuitBreaker, quickServiceCircuitBreaker);
  }

  @Test
  void testFailure_OpenStateTransition() {
    // Calling delayed service, which will be unhealthy till 4 seconds
    assertEquals("Delayed service is down", monitoringService.delayedServiceResponse());
    // As failure threshold is "1", the circuit breaker is changed to OPEN
    assertEquals("OPEN", delayedServiceCircuitBreaker.getState());
    // As circuit state is OPEN, we expect a quick fallback response from circuit breaker.
    assertEquals("Delayed service is down", monitoringService.delayedServiceResponse());

    // Meanwhile, the quick service is responding and the circuit state is CLOSED
    assertEquals("Quick Service is working", monitoringService.quickServiceResponse());
    assertEquals("CLOSED", quickServiceCircuitBreaker.getState());
  }

  @Test
  void testFailure_HalfOpenStateTransition() {
    // Calling delayed service, which will be unhealthy till 4 seconds
    assertEquals("Delayed service is down", monitoringService.delayedServiceResponse());
    // As failure threshold is "1", the circuit breaker is changed to OPEN
    assertEquals("OPEN", delayedServiceCircuitBreaker.getState());

    // Waiting for recovery period of 2 seconds for circuit breaker to retry service.
    try {
      LOGGER.info("Waiting 2s for delayed service to become responsive");
      Thread.sleep(2000);
    } catch (InterruptedException e) {
      LOGGER.error("An error occurred: ", e);
    }
    // After 2 seconds, the circuit breaker should move to "HALF_OPEN" state and retry fetching
    // response from service again
    assertEquals("HALF_OPEN", delayedServiceCircuitBreaker.getState());
  }

  @Test
  void testRecovery_ClosedStateTransition() {
    // Calling delayed service, which will be unhealthy till 4 seconds
    assertEquals("Delayed service is down", monitoringService.delayedServiceResponse());
    // As failure threshold is "1", the circuit breaker is changed to OPEN
    assertEquals("OPEN", delayedServiceCircuitBreaker.getState());

    // Waiting for 4 seconds, which is enough for DelayedService to become healthy and respond
    // successfully.
    try {
      LOGGER.info("Waiting 4s for delayed service to become responsive");
      Thread.sleep(4000);
    } catch (InterruptedException e) {
      LOGGER.error("An error occurred: ", e);
    }
    // As retry period is 2 seconds (<4 seconds of wait), hence the circuit breaker should be back
    // in HALF_OPEN state.
    assertEquals("HALF_OPEN", delayedServiceCircuitBreaker.getState());
    // Check the success response from delayed service.
    assertEquals("Delayed service is working", monitoringService.delayedServiceResponse());
    // As the response is success, the state should be CLOSED
    assertEquals("CLOSED", delayedServiceCircuitBreaker.getState());
  }
}