/*
    * 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
    *
    *      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 org.apache.commons.math4.neuralnet;
  
  import org.junit.Test;
  import org.junit.Assert;
  
  /**
   * Tests for {@link Neuron}.
   */
  public class NeuronTest {
      @Test
      public void testGetIdentifier() {
          final long id = 1234567;
          final Neuron n = new Neuron(id, new double[] {0 });
  
          Assert.assertEquals(id, n.getIdentifier());
      }
  
      @Test
      public void testGetSize() {
          final double[] features = {-1, -1e-97, 0, 23.456, 9.01e203};
          final Neuron n = new Neuron(1, features);
          Assert.assertEquals(features.length, n.getSize());
      }
  
      @Test
      public void testGetFeatures() {
          final double[] features = {-1, -1e-97, 0, 23.456, 9.01e203};
          final Neuron n = new Neuron(1, features);
  
          final double[] f = n.getFeatures();
          // Accessor returns a copy.
          Assert.assertFalse(f == features);
  
          // Values are the same.
          Assert.assertEquals(features.length, f.length);
          for (int i = 0; i < features.length; i++) {
              Assert.assertEquals(features[i], f[i], 0d);
          }
      }
  
      @Test
      public void testCompareAndSetFeatures() {
          final Neuron n = new Neuron(1, new double[] {0 });
          double[] expect = n.getFeatures();
          double[] update = new double[] {expect[0] + 1.23};
  
          // Test "success".
          boolean ok = n.compareAndSetFeatures(expect, update);
          // Check that the update is reported as successful.
          Assert.assertTrue(ok);
          // Check that the new value is correct.
          Assert.assertEquals(update[0],  n.getFeatures()[0], 0d);
  
          // Test "failure".
          double[] update1 = new double[] {update[0] + 4.56};
          // Must return "false" because the neuron has been
          // updated: a new update can only succeed if "expect"
          // is set to the new features.
          ok = n.compareAndSetFeatures(expect, update1);
          // Check that the update is reported as failed.
          Assert.assertFalse(ok);
          // Check that the value was not changed.
          Assert.assertEquals(update[0],  n.getFeatures()[0], 0d);
      }
  
      @Test
      public void testCopy() {
          final Neuron n = new Neuron(1, new double[] {9.87 });
  
          // Update original.
          double[] update = new double[] {n.getFeatures()[0] + 2.34};
          n.compareAndSetFeatures(n.getFeatures(), update);
  
          // Create a copy.
          final Neuron copy = n.copy();
  
          // Check that original and copy have the same value.
          Assert.assertTrue(n.getFeatures()[0] == copy.getFeatures()[0]);
          Assert.assertEquals(n.getNumberOfAttemptedUpdates(),
                              copy.getNumberOfAttemptedUpdates());
  
          // Update original.
         update = new double[] {1.23 * n.getFeatures()[0]};
         n.compareAndSetFeatures(n.getFeatures(), update);
 
         // Check that original and copy differ.
         Assert.assertFalse(n.getFeatures()[0] == copy.getFeatures()[0]);
         Assert.assertNotEquals(n.getNumberOfSuccessfulUpdates(),
                                copy.getNumberOfSuccessfulUpdates());
     }
 }