content: /*
   * 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
   *
   * https://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.trevni;
  
  import java.util.Random;
  
  import java.nio.ByteBuffer;
  
  import static org.junit.jupiter.api.Assertions.assertEquals;
  import static org.junit.jupiter.api.Assertions.assertTrue;
  
  import org.junit.jupiter.api.Test;
  
  public class TestUtil {
  
    private static long seed;
    private static boolean seedSet;
  
    /**
     * Returns the random seed for this test run. By default uses the current time,
     * but a test run can be replicated by specifying the "test.seed" system
     * property. The seed is printed the first time it's accessed so that failures
     * can be replicated if needed.
     */
    public static long getRandomSeed() {
      if (!seedSet) {
        String configured = System.getProperty("test.seed");
        if (configured != null)
          seed = Long.valueOf(configured);
        else
          seed = System.currentTimeMillis();
        System.err.println("test.seed=" + seed);
        seedSet = true;
      }
      return seed;
    }
  
    public static void resetRandomSeed() {
      seedSet = false;
    }
  
    public static Random createRandom() {
      return new Random(getRandomSeed());
    }
  
    public static ByteBuffer randomBytes(Random random) {
      byte[] bytes = new byte[randomLength(random)];
      random.nextBytes(bytes);
      return ByteBuffer.wrap(bytes);
    }
  
    public static String randomString(Random random) {
      int length = randomLength(random);
      char[] chars = new char[length];
      for (int i = 0; i < length; i++)
        chars[i] = (char) ('a' + random.nextInt('z' - 'a'));
      return new String(chars);
    }
  
    /**
     * Returns [0-15] 15/16 times. Returns [0-255] 255/256 times. Returns [0-4095]
     * 4095/4096 times. Returns [0-65535] every time.
     */
    public static int randomLength(Random random) {
      int n = random.nextInt();
      if (n < 0)
        n = -n;
      return n & ((n & 0xF0000) != 0 ? 0xF : ((n & 0xFF0000) != 0 ? 0xFF : ((n & 0xFFF0000) != 0 ? 0xFFF : 0xFFFF)));
    }
  
    @Test
    void randomLength() {
      long total = 0;
      int count = 1024 * 1024;
      int min = Short.MAX_VALUE;
      int max = 0;
      Random r = createRandom();
      for (int i = 0; i < count; i++) {
        int length = randomLength(r);
        if (min > length)
          min = length;
        if (max < length)
          max = length;
        total += length;
      }
      assertEquals(0, min);
      assertTrue(max > 1024 * 32);
  
      float average = total / (float) count;
      assertTrue(average > 16.0f);
      assertTrue(average < 64.0f);
  
    }
  
  }
  