/**
 * Copyright 2016 LinkedIn Corp. 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.
 */
package com.github.ambry.utils;

import java.util.Random;


/**
 * A class consisting of common util methods useful for tests.
 */
public class TestUtils {
  public static final Random RANDOM = new Random();

  /**
   * Return the number of threads currently running with a name containing the given pattern.
   * @param pattern the pattern to compare
   * @return the number of threads currently running with a name containing the given pattern.
   */
  public static int numThreadsByThisName(String pattern) {
    int count = 0;
    for (Thread t : Thread.getAllStackTraces().keySet()) {
      if (t.getName().contains(pattern)) {
        count++;
      }
    }
    return count;
  }

  /**
   * Return the thread with a name that contains the given name. If there are multiple such threads,
   * return the first such thread.
   * @param pattern the pattern to compare
   * @return the first thread with a name that contains the given pattern.
   */
  public static Thread getThreadByThisName(String pattern) {
    Thread thread = null;
    for (Thread t : Thread.getAllStackTraces().keySet()) {
      if (t.getName().contains(pattern)) {
        thread = t;
        break;
      }
    }
    return thread;
  }

  /**
   * Gets a byte array of length {@code size} with random bytes.
   * @param size the required length of the random byte array.
   * @return a byte array of length {@code size} with random bytes.
   */
  public static byte[] getRandomBytes(int size) {
    byte[] bytes = new byte[size];
    RANDOM.nextBytes(bytes);
    return bytes;
  }
}