001    /*
002     * Created on Jul 25, 2010
003     * 
004     * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
005     * the License. You may obtain a copy of the License at
006     * 
007     * http://www.apache.org/licenses/LICENSE-2.0
008     * 
009     * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
010     * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
011     * specific language governing permissions and limitations under the License.
012     * 
013     * Copyright @2010-2011 the original author or authors.
014     */
015    package org.fest.assertions.core;
016    
017    import java.util.Comparator;
018    
019    /**
020     * Assertions applicable to groups of values that can be enumerated (e.g. arrays, collections or strings.)
021     * @param <S> the "self" type of this assertion class. Please read &quot;<a href="http://bit.ly/anMa4g"
022     *          target="_blank">Emulating 'self types' using Java Generics to simplify fluent API implementation</a>&quot;
023     *          for more details.
024     * @param <T> the type of elements of the "actual" value.
025     * 
026     * @author Yvonne Wang
027     * @author Alex Ruiz
028     * @author Mikhail Mazursky
029     */
030    public interface EnumerableAssert<S extends EnumerableAssert<S, T>, T> {
031    
032      /**
033       * Verifies that the actual group of values is {@code null} or empty.
034       * @throws AssertionError if the actual group of values is not {@code null} or not empty.
035       */
036      void isNullOrEmpty();
037    
038      /**
039       * Verifies that the actual group of values is empty.
040       * @throws AssertionError if the actual group of values is not empty.
041       */
042      void isEmpty();
043    
044      /**
045       * Verifies that the actual group of values is not empty.
046       * @return {@code this} assertion object.
047       * @throws AssertionError if the actual group of values is empty.
048       */
049      S isNotEmpty();
050    
051      /**
052       * Verifies that the number of values in the actual group is equal to the given one.
053       * @param expected the expected number of values in the actual group.
054       * @return {@code this} assertion object.
055       * @throws AssertionError if the number of values of the actual group is not equal to the given one.
056       */
057      S hasSize(int expected);
058    
059      /**
060       * Use given custom comparator instead of relying on actual type A <code>equals</code> method to compare group
061       * elements for incoming assertion checks.
062       * <p>
063       * Custom comparator is bound to assertion instance, meaning that if a new assertion is created, it will use default
064       * comparison strategy.
065       * <p>
066       * Examples :
067       * 
068       * <pre>
069       * // compares invoices by payee 
070       * assertThat(invoiceList).usingComparator(invoicePayeeComparator).isEqualTo(expectedInvoiceList).
071       * 
072       * // compares invoices by date, doesNotHaveDuplicates and contains both use the given invoice date comparator
073       * assertThat(invoiceList).usingComparator(invoiceDateComparator).doesNotHaveDuplicates().contains(may2010Invoice)
074       * 
075       * // as assertThat(invoiceList) creates a new assertion, it falls back to standard comparison strategy 
076       * // based on Invoice's equal method to compare invoiceList elements to lowestInvoice.                                                      
077       * assertThat(invoiceList).contains(lowestInvoice).
078       * 
079       * // standard comparison : the fellowshipOfTheRing includes Gandalf but not Sauron (believe me) ...
080       * assertThat(fellowshipOfTheRing).contains(gandalf)
081       *                                .doesNotContain(sauron);
082       * 
083       * // ... but if we compare only races, Sauron is in fellowshipOfTheRing because he's a Maia like Gandalf.
084       * assertThat(fellowshipOfTheRing).usingElementComparator(raceComparator)
085       *                                .contains(sauron);
086       * </pre>
087       * 
088       * @param customComparator the comparator to use for incoming assertion checks.
089       * @throws NullPointerException if the given comparator is {@code null}.
090       * @return {@code this} assertion object.
091       */
092      S usingElementComparator(Comparator<? super T> customComparator);
093    
094      /**
095       * Revert to standard comparison for incoming assertion group element checks.
096       * <p>
097       * This method should be used to disable a custom comparison strategy set by calling
098       * {@link #usingElementComparator(Comparator)}.
099       * @return {@code this} assertion object.
100       */
101      S usingDefaultElementComparator();
102    }