package com.atlassian.vcache.internal.core.service;
   
   import com.atlassian.vcache.VCacheException;
   
   import java.util.Map;
   import java.util.Set;
   
   /**
    * Provides common functionality for factories.
   *
   * @since 1.9.0
   */
  public class FactoryUtils {
      public static <K, V> void verifyFactoryResult(Map<K, V> factoryResult, Set<K> expectedKeys) {
          // Easy, look for a mismatch
          if (expectedKeys.size() != factoryResult.size()) {
              throw new VCacheException("Factory returned " + factoryResult.size()
                      + " entries when " + expectedKeys.size() + " were expected. Expected keys "
                      + expectedKeys + " but got " + factoryResult.keySet() + ".");
          }
  
          // Now ensure that the keys align
          final long numberOfUnknownKeys = factoryResult.keySet().stream()
                  .filter(k -> !expectedKeys.contains(k))
                  .count();
          if (numberOfUnknownKeys > 0) {
              throw new VCacheException("Factory returned the keys " + factoryResult.keySet()
                      + " when expected " + expectedKeys + ".");
          }
      }
  }