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/**
 *  Copyright (c) 2011, The Staccato-Commons Team
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU Lesser General Public License as published by
 *  the Free Software Foundation; version 3 of the License.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser General Public License for more details.
 */

/*
 Copyright (c) 2010, The Staccato-Commons Team

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU Lesser General Public License as published by
 the Free Software Foundation; version 3 of the License.

 This program is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 GNU Lesser General Public License for more details.
 */
package net.sf.staccatocommons.testing.junit.theories;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;
import static org.junit.Assume.assumeTrue;

import org.junit.experimental.theories.Theories;
import org.junit.experimental.theories.Theory;
import org.junit.runner.RunWith;

/**
 * @author flbulgarelli
 * 
 */
@RunWith(Theories.class)
public abstract class WellDefinedEqualsTheories {

  /**
   * Tests that equality is reflexive: o1.equals(o1)
   */
  @Theory
  public void testEqualsReflexive(Object o1) throws Exception {
    assertTrue(o1.equals(o1));
  }

  /**
   * Test that equality is symmetric
   */
  @Theory
  public void testEqualsSymmetric(Object o1, Object o2) throws Exception {
    assumeTrue(o1.equals(o2));
    assertTrue(o2.equals(o1));
  }

  /**
   * Tests that equality is transitive: if o1.equals(o2) and o2.equals(o3), then
   * o1.equals(o3)
   */
  @Theory
  public void testEqualsTransitive(Object o1, Object o2, Object o3) throws Exception {
    assumeTrue(o1.equals(o2));
    assumeTrue(o2.equals(o3));
    assertTrue(o1.equals(o3));
  }

  /**
   * Test that equals is consistent along multiple invocation as long as fields
   * invoveld in test do not change (rule nº4) This test is inherently difficult
   * of generalize, an it just test that two invocation of equals have the same
   * result
   */
  @Theory
  public void testEqualsConsistent(Object o1, Object o2) throws Exception {
    assertEquals(o1.equals(o2), o1.equals(o2));
  }

  /**
   * Tests that an object is never equal to null (rule nº5)
   */
  @Theory
  public void testNeverEqualsToNull(Object o1) throws Exception {
    assertFalse(o1.equals(null));
  }

  /**
   * Tests that hashcode is repeatable as long as receptor is not mutated
   */
  @Theory
  public void testHasCodeConsistent(Object o1) throws Exception {
    assertEquals(o1.hashCode(), o1.hashCode());
  }

  /**
   * Tests that if tow objects are equal, then their hashcodes are equal, too
   * (rule nº2)
   */
  @Theory
  public void testHashCodeConsistentWithEquals(Object o1, Object o2) throws Exception {
    assumeTrue(o1.equals(o2));
    assertEquals(o1.hashCode(), o2.hashCode());
  }

}