Retry.java

/*
 * Copyright 2013 Google Inc. All Rights Reserved.
 *
 * 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 com.google.jenkins.plugins.dsl;

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

/**
 * TODO(mattmoor): We need to get to the bottom of the intermittent
 * type loading issues we see with Jenkins.  As a stopgap, allow our
 * tests to retry a handful of times.
 *
 * Source: http://stackoverflow.com/questions/8295100/         \
 *            how-to-re-run-failed-junit-tests-immediately
 */
public class Retry implements TestRule {
  public Retry(int retryCount) {
    this.retryCount = retryCount;
  }
  private final int retryCount;

  public Statement apply(Statement base, Description description) {
    return statement(base, description);
  }

  private Statement statement(final Statement base,
      final Description description) {
    return new Statement() {
      @Override
      public void evaluate() throws Throwable {
        Throwable caughtThrowable = null;

        // implement retry logic here
        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");
          }
        }
        System.err.println(description.getDisplayName() + ": giving up after " +
            retryCount + " failures");
        throw caughtThrowable;
      }
    };
  }
}