code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed 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
   *
   * http://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 io.reactivex.rxjava3.core;
  
  import org.junit.rules.TestRule;
  import org.junit.runner.Description;
  import org.junit.runners.model.Statement;
  
  /**
   * Test rule to retry flaky tests.
   * <a href="http://stackoverflow.com/a/8301639/61158">From Stackoverflow</a>.
   */
  public class Retry implements TestRule {
  
      final class RetryStatement extends Statement {
          private final Statement base;
          private final Description description;
  
          RetryStatement(Statement base, Description description) {
              this.base = base;
              this.description = description;
          }
  
          @Override
          public void evaluate() throws Throwable {
              Throwable caughtThrowable = null;
  
              for (int i = 0; i < retryCount; i++) {
                  try {
                      base.evaluate();
                      return;
                  } catch (Throwable t) {
                      caughtThrowable = t;
                      System.err.println(description.getDisplayName() + ": run " + (i + 1) + " failed");
                      int n = sleep;
                      if (backoff && i != 0) {
                          n = n * (2 << i);
                      }
                      Thread.sleep(n);
                  }
              }
              System.err.println(description.getDisplayName() + ": giving up after " + retryCount + " failures");
              throw caughtThrowable;
          }
      }
  
      final int retryCount;
  
      final int sleep;
  
      final boolean backoff;
  
      public Retry(int retryCount, int sleep, boolean backoff) {
          this.retryCount = retryCount;
          this.sleep = sleep;
          this.backoff = backoff;
      }
  
      @Override
      public Statement apply(Statement base, Description description) {
          return statement(base, description);
      }
  
      private Statement statement(final Statement base, final Description description) {
          return new RetryStatement(base, description);
      }
  }
  