jgit/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/DescribeCommandTest.java

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 * This program and the accompanying materials are made available
 * under the terms of the Eclipse Distribution License v1.0 which
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 * available at http://www.eclipse.org/org/documents/edl-v10.php
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package org.eclipse.jgit.api;

import org.eclipse.jgit.api.errors.GitAPIException;
import org.eclipse.jgit.junit.RepositoryTestCase;
import org.eclipse.jgit.lib.ObjectId;
import org.junit.Test;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import static org.junit.Assert.*;

public class DescribeCommandTest extends RepositoryTestCase {

	private Git git;

	@Override
	public void setUp() throws Exception {
		super.setUp();
		git = new Git(db);
	}

	@Test(expected = IllegalArgumentException.class)
	public void noTargetSet() throws Exception {
		git.describe().call();
	}

	@Test
	public void testDescribe() throws Exception {
		ObjectId c1 = modify("aaa");

		ObjectId c2 = modify("bbb");
		tag("t1");

		ObjectId c3 = modify("ccc");
		tag("t2");

		ObjectId c4 = modify("ddd");

		assertNull(describe(c1));
		assertEquals("t1", describe(c2));
		assertEquals("t2", describe(c3));

		assertNameStartsWith(c4, "3e563c5");
		// the value verified with git-describe(1)
		assertEquals("t2-1-g3e563c5", describe(c4));
	}

	/**
	 * Make sure it finds a tag when not all ancestries include a tag.
	 *
	 * <pre>
	 * c1 -+-> T  -
	 *     |       |
	 *     +-> c3 -+-> c4
	 * </pre>
	 *
	 * @throws Exception
	 */
	@Test
	public void testDescribeBranch() throws Exception {
		ObjectId c1 = modify("aaa");

		ObjectId c2 = modify("bbb");
		tag("t");

		branch("b", c1);

		ObjectId c3 = modify("ccc");

		ObjectId c4 = merge(c2);

		assertNameStartsWith(c4, "119892b");
		assertEquals("t-2-g119892b", describe(c4)); // 2 commits: c4 and c3
		assertNull(describe(c3));
	}

	private void branch(String name, ObjectId base) throws GitAPIException {
		git.checkout().setCreateBranch(true).setName(name)
				.setStartPoint(base.name()).call();
	}

	/**
	 * When t2 dominates t1, it's clearly preferable to describe by using t2.
	 *
	 * <pre>
	 * t1 -+-> t2  -
	 *     |       |
	 *     +-> c3 -+-> c4
	 * </pre>
	 *
	 * @throws Exception
	 */
	@Test
	public void t1DominatesT2() throws Exception {
		ObjectId c1 = modify("aaa");
		tag("t1");

		ObjectId c2 = modify("bbb");
		tag("t2");

		branch("b", c1);

		ObjectId c3 = modify("ccc");

		ObjectId c4 = merge(c2);

		assertNameStartsWith(c4, "119892b");
		assertEquals("t2-2-g119892b", describe(c4)); // 2 commits: c4 and c3

		assertNameStartsWith(c3, "0244e7f");
		assertEquals("t1-1-g0244e7f", describe(c3));
	}

	/**
	 * When t1 is nearer than t2, t2 should be found
	 *
	 * <pre>
	 * c1 -+-> c2 -> t1 -+
	 *     |             |
	 *     +-> t2 -> c3 -+-> c4
	 * </pre>
	 *
	 * @throws Exception
	 */
	@Test
	public void t1nearerT2() throws Exception {
		ObjectId c1 = modify("aaa");
		modify("bbb");
		ObjectId t1 = modify("ccc");
		tag("t1");

		branch("b", c1);
		modify("ddd");
		tag("t2");
		modify("eee");
		ObjectId c4 = merge(t1);

		assertNameStartsWith(c4, "bb389a4");
		assertEquals("t1-3-gbb389a4", describe(c4));
	}

	/**
	 * When t1 and t2 have same depth native git seems to add the depths of both
	 * paths
	 *
	 * <pre>
	 * c1 -+-> t1 -> c2 -+
	 *     |             |
	 *     +-> t2 -> c3 -+-> c4
	 * </pre>
	 *
	 * @throws Exception
	 */
	@Test
	public void t1sameDepthT2() throws Exception {
		ObjectId c1 = modify("aaa");
		modify("bbb");
		tag("t1");
		ObjectId c2 = modify("ccc");

		branch("b", c1);
		modify("ddd");
		tag("t2");
		modify("eee");
		ObjectId c4 = merge(c2);

		assertNameStartsWith(c4, "bb389a4");
		assertEquals("t2-4-gbb389a4", describe(c4));
	}

	private ObjectId merge(ObjectId c2) throws GitAPIException {
		return git.merge().include(c2).call().getNewHead();
	}

	private ObjectId modify(String content) throws Exception {
		File a = new File(db.getWorkTree(), "a.txt");
		touch(a, content);
		return git.commit().setAll(true).setMessage(content).call().getId();
	}

	private void tag(String tag) throws GitAPIException {
		git.tag().setName(tag).setMessage(tag).call();
	}

	private static void touch(File f, String contents) throws Exception {
		FileWriter w = new FileWriter(f);
		w.write(contents);
		w.close();
	}

	private String describe(ObjectId c1) throws GitAPIException, IOException {
		return git.describe().setTarget(c1).call();
	}

	private static void assertNameStartsWith(ObjectId c4, String prefix) {
		assertTrue(c4.name(), c4.name().startsWith(prefix));
	}
}