JUnit rule to set system. default time zone.

TimeZoneRule.java

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

import java.util.TimeZone;

/**
 * Sets the default time zone to be used for JUnit tests. The system default time zone is reset
 * after each test method. Use it like any other JUnit rule.
 *
 * MIT License
 *
 * Copyright (c) 2020 Christopher Campo
 *
 * 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.
 */
public class TimeZoneRule implements TestRule {

  private final String timeZoneId;

  public TimeZoneRule() {
    this("UTC");
  }

  public TimeZoneRule(final String timeZoneId) {
    this.timeZoneId = timeZoneId;
  }

  @Override
  public Statement apply(final Statement base, final Description description) {
    return new Statement() {
      @Override
      public void evaluate() throws Throwable {
        final TimeZone defaultTimeZone = TimeZone.getDefault();
        try {
          TimeZone.setDefault(TimeZone.getTimeZone(timeZoneId));
          base.evaluate();
        } finally {
          TimeZone.setDefault(defaultTimeZone);
        }
      }
    };
  }
}