AssertWithTimeout.java

/*
 * Copyright (c) 2011-2015 Spotify AB
 *
 * 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.spotify.google.cloud.pubsub.client;

import org.hamcrest.Matcher;

import java.util.concurrent.TimeUnit;
import java.util.function.Supplier;

import static org.junit.Assert.assertThat;

class AssertWithTimeout {

  static <T> void assertThatWithin(final long timeout, final TimeUnit unit,
                                   final Supplier<T> actual, final Matcher<? super T> matcher) {
    final long start = System.nanoTime();
    final long deadline = start + unit.toNanos(timeout);
    while (true) {
      if (System.nanoTime() > deadline) {
        assertThat(actual.get(), matcher);
        return;
      }
      if (matcher.matches(actual.get())) {
        return;
      }
      try {
        Thread.sleep(50);
      } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
        return;
      }
    }
  }

}