Support rebasing independent branches

With completely independent branches, there is no merge base. In this
case, the list of commits must include the root commit of the branch to
be rebased.

Bug: 581832
Change-Id: I0f5bdf179d5b07ff09f1a274d61c7a0b1c0011c6
Signed-off-by: Thomas Wolf <twolf@apache.org>

1 files changed, 141 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java
index d574e45f6f..7f820b0433 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RebaseCommandTest.java
@@ -76,6 +76,10 @@ public class RebaseCommandTest extends RepositoryTestCase {
 
 	private static final String FILE1 = "file1";
 
+	private static final String FILE2 = "file2";
+
+	private static final String FILE3 = "file3";
+
 	protected Git git;
 
 	@Override
@@ -191,6 +195,143 @@ public class RebaseCommandTest extends RepositoryTestCase {
 	}
 
 	/**
+	 * Rebase a single root commit onto an independent branch.
+	 *
+	 * <pre>
+	 * A (master)
+	 *
+	 * B - C (orphan)
+	 * </pre>
+	 *
+	 * to
+	 *
+	 * <pre>
+	 * A
+	 *
+	 * B - C (orphan) - A' (master)
+	 * </pre>
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testRebaseRootCommit() throws Exception {
+		writeTrashFile(FILE1, FILE1);
+		writeTrashFile(FILE2, FILE2);
+		git.add().addFilepattern(FILE1).addFilepattern(FILE2).call();
+		RevCommit first = git.commit().setMessage("Add files").call();
+		File file1 = new File(db.getWorkTree(), FILE1);
+		File file2 = new File(db.getWorkTree(), FILE2);
+		assertTrue(file1.exists());
+		assertTrue(file2.exists());
+		// Create an independent branch
+		git.checkout().setOrphan(true).setName("orphan").call();
+		git.rm().addFilepattern(FILE1).addFilepattern(FILE2).call();
+		assertFalse(file1.exists());
+		assertFalse(file2.exists());
+		writeTrashFile(FILE1, "something else");
+		git.add().addFilepattern(FILE1).call();
+		RevCommit orphanBase = git.commit().setMessage("Orphan base").call();
+		writeTrashFile(FILE1, FILE1);
+		git.add().addFilepattern(FILE1).call();
+		RevCommit orphanTop = git.commit().setMessage("Same file1").call();
+		checkoutBranch("refs/heads/master");
+		assertEquals(first.getId(), db.resolve("HEAD"));
+		RebaseResult res = git.rebase().setUpstream("refs/heads/orphan").call();
+		assertEquals(Status.OK, res.getStatus());
+		Iterable<RevCommit> log = git.log().add(db.resolve("HEAD")).call();
+		ObjectId[] ids = { orphanTop.getId(), orphanBase.getId() };
+		int nOfCommits = 0;
+		for (RevCommit c : log) {
+			nOfCommits++;
+			if (nOfCommits == 1) {
+				assertEquals("Add files", c.getFullMessage());
+			} else {
+				assertEquals(ids[nOfCommits - 2], c.getId());
+			}
+		}
+		assertEquals(3, nOfCommits);
+		assertTrue(file1.exists());
+		checkFile(file1, FILE1);
+		assertTrue(file2.exists());
+		checkFile(file2, FILE2);
+	}
+
+	/**
+	 * Rebase a branch onto an independent branch.
+	 *
+	 * <pre>
+	 * A - B (master)
+	 *
+	 * C - D (orphan)
+	 * </pre>
+	 *
+	 * to
+	 *
+	 * <pre>
+	 * A - B
+	 *
+	 * C - D (orphan) - A' - B' (master)
+	 * </pre>
+	 *
+	 * @throws Exception
+	 */
+	@Test
+	public void testRebaseNoMergeBase() throws Exception {
+		writeTrashFile(FILE1, FILE1);
+		writeTrashFile(FILE2, FILE2);
+		git.add().addFilepattern(FILE1).addFilepattern(FILE2).call();
+		git.commit().setMessage("Add files").call();
+		writeTrashFile(FILE3, FILE3);
+		git.add().addFilepattern(FILE3).call();
+		RevCommit first = git.commit().setMessage("File3").call();
+		File file1 = new File(db.getWorkTree(), FILE1);
+		File file2 = new File(db.getWorkTree(), FILE2);
+		File file3 = new File(db.getWorkTree(), FILE3);
+		assertTrue(file1.exists());
+		assertTrue(file2.exists());
+		assertTrue(file3.exists());
+		// Create an independent branch
+		git.checkout().setOrphan(true).setName("orphan").call();
+		git.rm()
+				.addFilepattern(FILE1)
+				.addFilepattern(FILE2)
+				.addFilepattern(FILE3)
+				.call();
+		assertFalse(file1.exists());
+		assertFalse(file2.exists());
+		assertFalse(file3.exists());
+		writeTrashFile(FILE1, "something else");
+		git.add().addFilepattern(FILE1).call();
+		RevCommit orphanBase = git.commit().setMessage("Orphan base").call();
+		writeTrashFile(FILE1, FILE1);
+		git.add().addFilepattern(FILE1).call();
+		RevCommit orphanTop = git.commit().setMessage("Same file1").call();
+		checkoutBranch("refs/heads/master");
+		assertEquals(first.getId(), db.resolve("HEAD"));
+		RebaseResult res = git.rebase().setUpstream("refs/heads/orphan").call();
+		assertEquals(Status.OK, res.getStatus());
+		Iterable<RevCommit> log = git.log().add(db.resolve("HEAD")).call();
+		String[] msgs = { "File3", "Add files" };
+		ObjectId[] ids = { orphanTop.getId(), orphanBase.getId() };
+		int nOfCommits = 0;
+		for (RevCommit c : log) {
+			nOfCommits++;
+			if (nOfCommits <= msgs.length) {
+				assertEquals(msgs[nOfCommits - 1], c.getFullMessage());
+			} else {
+				assertEquals(ids[nOfCommits - msgs.length - 1], c.getId());
+			}
+		}
+		assertEquals(4, nOfCommits);
+		assertTrue(file1.exists());
+		checkFile(file1, FILE1);
+		assertTrue(file2.exists());
+		checkFile(file2, FILE2);
+		assertTrue(file3.exists());
+		checkFile(file3, FILE3);
+	}
+
+	/**
 	 * Create the following commits and then attempt to rebase topic onto
 	 * master. This will serialize the branches.
 	 *