/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      https://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.lang3.concurrent;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertFalse;
  import static org.junit.jupiter.api.Assertions.assertThrows;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import org.apache.commons.lang3.AbstractLangTest;
  import org.junit.jupiter.api.Test;
  
  /**
   * Test class for {@code ThresholdCircuitBreaker}.
   */
  class ThresholdCircuitBreakerTest extends AbstractLangTest {
  
      /**
       * Threshold used in tests.
       */
      private static final long threshold = 10L;
  
      private static final long zeroThreshold = 0L;
  
      /**
       * Tests that closing a {@code ThresholdCircuitBreaker} resets the internal counter.
       */
      @Test
      void testClosingThresholdCircuitBreaker() {
          final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(threshold);
          circuit.incrementAndCheckState(9L);
          circuit.close();
          // now the internal counter is back at zero, not 9 anymore. So it is safe to increment 9 again
          assertTrue(circuit.incrementAndCheckState(9L), "Internal counter was not reset back to zero");
      }
  
      /**
       * Tests that we can get the threshold value correctly.
       */
      @Test
      void testGettingThreshold() {
          final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(threshold);
          assertEquals(Long.valueOf(threshold), Long.valueOf(circuit.getThreshold()), "Wrong value of threshold");
      }
  
      /**
       * Tests that a negative increment is rejected: the counter must only move toward the threshold.
       */
      @Test
      void testNegativeIncrementRejected() {
          final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(threshold);
          assertThrows(IllegalArgumentException.class, () -> circuit.incrementAndCheckState(-1L), "Negative increments must be rejected");
      }
  
      /**
       * Tests that overflowing the internal counter saturates and opens the circuit breaker instead of wrapping negative and silently disabling the trip
       * condition.
       */
      @Test
      void testOverflowSaturatesAndOpens() {
          final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(Long.MAX_VALUE);
          circuit.incrementAndCheckState(Long.MAX_VALUE);
          // Without saturation this would wrap negative and report the circuit closed forever.
          assertFalse(circuit.incrementAndCheckState(1L), "Overflow must open the circuit, not wrap the counter");
          assertFalse(circuit.checkState(), "Circuit must stay open after overflow");
      }
  
      /**
       * Tests that the threshold is working as expected when incremented and no exception is thrown.
       */
      @Test
      void testThreshold() {
          final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(threshold);
          circuit.incrementAndCheckState(9L);
          assertTrue(circuit.incrementAndCheckState(1L), "Circuit opened before reaching the threshold");
      }
  
      /**
       * Tests that exceeding the threshold raises an exception.
       */
      @Test
      void testThresholdCircuitBreakingException() {
          final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(threshold);
          circuit.incrementAndCheckState(9L);
          assertFalse(circuit.incrementAndCheckState(2L), "The circuit was supposed to be open after increment above the threshold");
     }
 
     /**
      * Test that when threshold is zero, the circuit breaker is always open.
      */
     @Test
     void testThresholdEqualsZero() {
         final ThresholdCircuitBreaker circuit = new ThresholdCircuitBreaker(zeroThreshold);
         assertFalse(circuit.incrementAndCheckState(0L), "When the threshold is zero, the circuit is supposed to be always open");
     }
 
 }