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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.assertTrue;
import static org.junit.Assume.assumeTrue;

import org.junit.experimental.theories.Theory;

/**
 * @author flbulgarelli
 * 
 */
public class WellDefinedCompareTheories extends WellDefinedEqualsTheories {

  private boolean consistentWithEquals;

  /**
   * Creates a new {@link WellDefinedCompareTheories}
   * 
   * @param consistentWithEquals
   *          if this theories must assume that the comparables under test are
   *          consistent with equals
   */
  public WellDefinedCompareTheories(boolean consistentWithEquals) {
    this.consistentWithEquals = consistentWithEquals;
  }

  /**
   * Test that sign of comparing x and y is the opposite of comparing y and x
   * (rule nº1)
   */
  @Theory
  public void testRule1(Comparable o1, Comparable o2) throws Exception {
    assertEquals(signum(o1.compareTo(o2)), -signum(o2.compareTo(o1)));
  }

  /**
   * Test that comparison is transitive (rule nº2)
   */
  @Theory
  public void testTransitive(Comparable o1, Comparable o2, Comparable o3) throws Exception {
    assumeTrue(o1.compareTo(o2) > 0);
    assumeTrue(o2.compareTo(o3) > 0);
    assertTrue(o1.compareTo(o3) > 0);
  }

  /**
   * Test rule nº3
   */
  @Theory
  public void testRule3(Comparable o1, Comparable o2, Comparable o3) throws Exception {
    assumeTrue(o1.compareTo(o2) == 0);
    assertEquals(signum(o1.compareTo(o3)), signum(o2.compareTo(o3)));
  }

  /**
   * Theory that tests consistency of compareTo with equals.
   * 
   * @param o1
   * @param o2
   * @throws Exception
   */
  @Theory
  public void testConsistentWithEquals(Comparable o1, Comparable o2) throws Exception {
    assumeTrue(consistentWithEquals);
    assertEquals(o1.equals(o2), o1.compareTo(o2) == 0);
  }

  private static int signum(int x) {
    if (x < 0)
      return -1;
    if (x > 0)
      return 1;
    return 0;
  }
}