code: /*
   * #%L
   * Simmetrics Core
   * %%
   * Copyright (C) 2014 - 2016 Simmetrics Authors
   * %%
   * 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.
   * #L%
   */
  package org.simmetrics;
  
  import static org.junit.Assert.fail;
  import java.util.Collection;
  import org.junit.Test;
  
  @SuppressWarnings("javadoc")
  public abstract class CollectionMetricTest<V, K extends Collection<V>> extends MetricTest<K> {
  
  	protected static class C<V, K extends Collection<V>> extends TestCase<K> {
  
  		public C(float similarity, K a, K b) {
  			super(similarity, a, b);
  		}
  
  	}
  	
  	@Override
  	protected abstract C<V,K>[] getTests();
  	
  	private void testsShouldContainCollectionWithNullVsWithouthNull(C<V, K>[] cs) {
  		for (C<V,K> t : cs) {
  			if (t.a.contains(null) ^ t.b.contains(null)) {
  				return;
  			}
  		}
  
  		fail("tests did not contain collection with null vs collection without null");
  	}
  
  	private void testIllegalArgumentException(Metric<K> metric) {
  		try {
  			metric.compare(getCollectionContainNull(), getEmpty());
  			fail("Metric should have thrown a illegal argument exception for the first argument");
  		} catch (IllegalArgumentException ignored) {
  			// Ignored
  		}
  
  		try {
  			metric.compare(getEmpty(), getCollectionContainNull());
  			fail("Metric should have thrown a illegal argument exception for the second argument");
  		} catch (IllegalArgumentException ignored) {
  			// Ignored
  		}
  
  		try {
  			metric.compare(getCollectionContainNull(), getCollectionContainNull());
  			fail("Metric should have thrown a illegal argument exception for either argument");
  		} catch (IllegalArgumentException ignored) {
  			// Ignored
  		}
  	}
  
  	protected abstract K getCollectionContainNull();
  
  	@Test
  	public void nullValues() {
  		if (supportsNullValues()) {
  			testsShouldContainCollectionWithNullVsWithouthNull(getTests());
  		} else {
  			testIllegalArgumentException(metric);	
  		}
  	}
  
  	protected boolean supportsNullValues() {
  		return true;
  	}
  
  }
  