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    * and other copyright owners as documented in the project's IP log.
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    * This program and the accompanying materials are made available
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  package org.eclipse.jgit.diff;
  
  import static org.junit.Assert.assertEquals;
  
  import org.junit.Test;
  
  
  public class HistogramDiffTest extends AbstractDiffTestCase {
  	@Override
  	protected HistogramDiff algorithm() {
  		HistogramDiff hd = new HistogramDiff();
  		hd.setFallbackAlgorithm(null);
  		return hd;
  	}
  
  	@Test
  	public void testEdit_NoUniqueMiddleSide_FlipBlocks() {
  		EditList r = diff(t("aRRSSz"), t("aSSRRz"));
  		assertEquals(2, r.size());
  		assertEquals(new Edit(1, 3, 1, 1), r.get(0)); // DELETE "RR"
  		assertEquals(new Edit(5, 5, 3, 5), r.get(1)); // INSERT "RR
  	}
  
  	@Test
  	public void testEdit_NoUniqueMiddleSide_Insert2() {
  		EditList r = diff(t("aRSz"), t("aRRSSz"));
  		assertEquals(1, r.size());
  		assertEquals(new Edit(2, 2, 2, 4), r.get(0));
  	}
  
  	@Test
  	public void testEdit_NoUniqueMiddleSide_FlipAndExpand() {
  		EditList r = diff(t("aRSz"), t("aSSRRz"));
  		assertEquals(2, r.size());
  		assertEquals(new Edit(1, 2, 1, 1), r.get(0)); // DELETE "R"
  		assertEquals(new Edit(3, 3, 2, 5), r.get(1)); // INSERT "SRR"
  	}
  
  	@Test
  	public void testEdit_LcsContainsUnique() {
  		EditList r = diff(t("nqnjrnjsnm"), t("AnqnjrnjsnjTnmZ"));
  		assertEquals(new Edit(0, 0, 0, 1), r.get(0)); // INSERT "A";
  		assertEquals(new Edit(9, 9, 10, 13), r.get(1)); // INSERT "jTn";
  		assertEquals(new Edit(10, 10, 14, 15), r.get(2)); // INSERT "Z";
  		assertEquals(3, r.size());
  	}
  
  	@Test
  	public void testExceedsChainLength_DuringScanOfA() {
  		HistogramDiff hd = new HistogramDiff();
  		hd.setFallbackAlgorithm(null);
  		hd.setMaxChainLength(3);
  
  		SequenceComparator<RawText> cmp = new SequenceComparator<RawText>() {
  			@Override
  			public boolean equals(RawText a, int ai, RawText b, int bi) {
 				return RawTextComparator.DEFAULT.equals(a, ai, b, bi);
 			}
 
 			@Override
 			public int hash(RawText a, int ai) {
 				return 1;
 			}
 		};
 
 		EditList r = hd.diff(cmp, t("RabS"), t("QabT"));
 		assertEquals(1, r.size());
 		assertEquals(new Edit(0, 4, 0, 4), r.get(0));
 	}
 
 	@Test
 	public void testExceedsChainLength_DuringScanOfB() {
 		HistogramDiff hd = new HistogramDiff();
 		hd.setFallbackAlgorithm(null);
 		hd.setMaxChainLength(1);
 
 		EditList r = hd.diff(RawTextComparator.DEFAULT, t("RaaS"), t("QaaT"));
 		assertEquals(1, r.size());
 		assertEquals(new Edit(0, 4, 0, 4), r.get(0));
 	}
 
 	@Test
 	public void testFallbackToMyersDiff() {
 		HistogramDiff hd = new HistogramDiff();
 		hd.setMaxChainLength(4);
 
 		RawTextComparator cmp = RawTextComparator.DEFAULT;
 		RawText ac = t("bbbbb");
 		RawText bc = t("AbCbDbEFbZ");
 		EditList r;
 
 		// Without fallback our results are limited due to collisions.
 		hd.setFallbackAlgorithm(null);
 		r = hd.diff(cmp, ac, bc);
 		assertEquals(1, r.size());
 
 		// Results go up when we add a fallback for the high collision regions.
 		hd.setFallbackAlgorithm(MyersDiff.INSTANCE);
 		r = hd.diff(cmp, ac, bc);
 		assertEquals(5, r.size());
 	}
 }