geode-junit/src/main/java/org/apache/geode/test/junit/rules/RetryRule.java

/*
 * 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
 *
 * 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 org.apache.geode.test.junit.rules;

import java.io.Serializable;

import org.junit.rules.TestRule;
import org.junit.runner.Description;
import org.junit.runners.model.Statement;

import org.apache.geode.test.junit.Retry;

/**
 * JUnit Rule that enables retrying a failed test up to a maximum number of retries.
 * </p>
 * RetryRule can be used globally for all tests in a test case by specifying a retryCount when
 * instantiating it:
 *
 * <pre>
 * {@literal @}Rule
 * public final RetryRule retryRule = new RetryRule(3);
 *
 * {@literal @}Test
 * public void shouldBeRetriedUntilPasses() {
 *   ...
 * }
 * </pre>
 * </p>
 * The above will result in 3 retries for every test in the test case.
 * </p>
 * RetryRule can be used locally for specific tests by annotating the test method with
 * {@literal @}Rule and specifying a retryCount for that test:
 *
 * <pre>
 * {@literal @}Rule
 * public final RetryRule retryRule = new RetryRule();
 *
 * {@literal @}Test
 * {@literal @}Retry(3)
 * public void shouldBeRetriedUntilPasses() {
 *   ...
 * }
 * </pre>
 * </p>
 * This version of RetryRule will retry a test that fails because of any kind of Throwable.
 */
public class RetryRule implements TestRule, Serializable {

  /**
   * Enables printing of failures to System.err even if test passes on a retry
   */
  private static final boolean LOG = false;

  private final AbstractRetryRule implementation;

  public RetryRule() {
    this.implementation = new LocalRetryRule();
  }

  public RetryRule(final int retryCount) {
    this.implementation = new GlobalRetryRule(retryCount);
  }

  @Override
  public Statement apply(final Statement base, final Description description) {
    return this.implementation.apply(base, description);
  }

  protected abstract class AbstractRetryRule implements TestRule, Serializable {
    protected AbstractRetryRule() {}

    protected void evaluate(final Statement base, final Description description,
        final int retryCount) throws Throwable {
      if (retryCount == 0) {

      }
      Throwable caughtThrowable = null;

      for (int count = 0; count < retryCount; count++) {
        try {
          base.evaluate();
          return;
        } catch (Throwable t) {
          caughtThrowable = t;
          debug(description.getDisplayName() + ": run " + (count + 1) + " failed");
        }
      }

      debug(description.getDisplayName() + ": giving up after " + retryCount + " failures");
      throw caughtThrowable;
    }

    private void debug(final String message) {
      if (LOG) {
        System.err.println(message);
      }
    }
  }

  /**
   * Implementation of RetryRule for all test methods in a test case
   */
  protected class GlobalRetryRule extends AbstractRetryRule {

    private final int retryCount;

    protected GlobalRetryRule(final int retryCount) {
      if (retryCount < 1) {
        throw new IllegalArgumentException("Retry count must be greater than zero");
      }
      this.retryCount = retryCount;
    }

    @Override
    public Statement apply(final Statement base, final Description description) {
      return new Statement() {
        @Override
        public void evaluate() throws Throwable {
          GlobalRetryRule.this.evaluatePerCase(base, description);
        }
      };
    }

    protected void evaluatePerCase(final Statement base, final Description description)
        throws Throwable {
      evaluate(base, description, this.retryCount);
    }
  }

  /**
   * Implementation of RetryRule for test methods annotated with Retry
   */
  protected class LocalRetryRule extends AbstractRetryRule {

    protected LocalRetryRule() {}

    @Override
    public Statement apply(final Statement base, final Description description) {
      return new Statement() {
        @Override
        public void evaluate() throws Throwable {
          LocalRetryRule.this.evaluatePerTest(base, description);
        }
      };
    }

    protected void evaluatePerTest(final Statement base, final Description description)
        throws Throwable {
      if (isTest(description)) {
        Retry retry = description.getAnnotation(Retry.class);
        int retryCount = getRetryCount(retry);
        evaluate(base, description, retryCount);
      }
    }

    private int getRetryCount(final Retry retry) {
      int retryCount = Retry.DEFAULT;

      if (retry != null) {
        retryCount = retry.value();
      }

      return retryCount;
    }

    private boolean isTest(final Description description) {
      return (description.isSuite() || description.isTest());
    }
  }
}