Implement a revert command

This is almost reverted cherry-pick, and the implementation is
almost identical. It orders the input to merge differently to get
the effect and produces a different commit message with the
default author, rather than the original author.

Change-Id: I39970091d9f7406ae7168b8efaab23a5e2c16bad
Signed-off-by: Robin Rosenberg <robin.rosenberg@dewire.com>

2 files changed, 159 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RevertCommandTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RevertCommandTest.java
new file mode 100644
index 0000000000..9eb44db866
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/api/RevertCommandTest.java
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2011, Robin Rosenberg
+ * and other copyright owners as documented in the project's IP log.
+ *
+ * This program and the accompanying materials are made available
+ * under the terms of the Eclipse Distribution License v1.0 which
+ * accompanies this distribution, is reproduced below, and is
+ * available at http://www.eclipse.org/org/documents/edl-v10.php
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or
+ * without modification, are permitted provided that the following
+ * conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above
+ *   copyright notice, this list of conditions and the following
+ *   disclaimer in the documentation and/or other materials provided
+ *   with the distribution.
+ *
+ * - Neither the name of the Eclipse Foundation, Inc. nor the
+ *   names of its contributors may be used to endorse or promote
+ *   products derived from this software without specific prior
+ *   written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
+ * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package org.eclipse.jgit.api;
+
+import static org.junit.Assert.*;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.Iterator;
+
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.api.errors.JGitInternalException;
+import org.eclipse.jgit.lib.RepositoryTestCase;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.junit.Test;
+
+/**
+ * Test cherry-pick command
+ */
+public class RevertCommandTest extends RepositoryTestCase {
+	@Test
+	public void testRevert() throws IOException, JGitInternalException,
+			GitAPIException {
+		Git git = new Git(db);
+
+		writeTrashFile("a", "first line\nsec. line\nthird line\n");
+		git.add().addFilepattern("a").call();
+		git.commit().setMessage("create a").call();
+
+		writeTrashFile("b", "content\n");
+		git.add().addFilepattern("b").call();
+		git.commit().setMessage("create b").call();
+
+		writeTrashFile("a", "first line\nsec. line\nthird line\nfourth line\n");
+		git.add().addFilepattern("a").call();
+		git.commit().setMessage("enlarged a").call();
+
+		writeTrashFile("a",
+				"first line\nsecond line\nthird line\nfourth line\n");
+		git.add().addFilepattern("a").call();
+		RevCommit fixingA = git.commit().setMessage("fixed a").call();
+
+		writeTrashFile("b", "first line\n");
+		git.add().addFilepattern("b").call();
+		git.commit().setMessage("fixed b").call();
+
+		git.revert().include(fixingA).call();
+
+		assertTrue(new File(db.getWorkTree(), "b").exists());
+		checkFile(new File(db.getWorkTree(), "a"),
+				"first line\nsec. line\nthird line\nfourth line\n");
+		Iterator<RevCommit> history = git.log().call().iterator();
+		assertEquals("Revert \"fixed a\"", history.next().getShortMessage());
+		assertEquals("fixed b", history.next().getFullMessage());
+		assertEquals("fixed a", history.next().getFullMessage());
+		assertEquals("enlarged a", history.next().getFullMessage());
+		assertEquals("create b", history.next().getFullMessage());
+		assertEquals("create a", history.next().getFullMessage());
+		assertFalse(history.hasNext());
+	}
+}
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/merge/CherryPickTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/merge/CherryPickTest.java
index 0ac42af52e..ff9f188348 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/merge/CherryPickTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/merge/CherryPickTest.java
@@ -128,6 +128,64 @@ public class CherryPickTest extends RepositoryTestCase {
 		assertFalse(tw.next());
 	}
 
+	@Test
+	public void testRevert() throws Exception {
+		// B---P---T
+		//
+		// Revert P, this should result in a tree with a
+		// from B and t from T as the change to a in P
+		// and addition of t in P is reverted.
+		//
+		// We use the standard merge, but change the order
+		// of the sources.
+		//
+		final DirCache treeB = db.readDirCache();
+		final DirCache treeP = db.readDirCache();
+		final DirCache treeT = db.readDirCache();
+		{
+			final DirCacheBuilder b = treeB.builder();
+			final DirCacheBuilder p = treeP.builder();
+			final DirCacheBuilder t = treeT.builder();
+
+			b.add(makeEntry("a", FileMode.REGULAR_FILE));
+
+			p.add(makeEntry("a", FileMode.REGULAR_FILE, "q"));
+			p.add(makeEntry("p-fail", FileMode.REGULAR_FILE));
+
+			t.add(makeEntry("a", FileMode.REGULAR_FILE, "q"));
+			t.add(makeEntry("p-fail", FileMode.REGULAR_FILE));
+			t.add(makeEntry("t", FileMode.REGULAR_FILE));
+
+			b.finish();
+			p.finish();
+			t.finish();
+		}
+
+		final ObjectInserter ow = db.newObjectInserter();
+		final ObjectId B = commit(ow, treeB, new ObjectId[] {});
+		final ObjectId P = commit(ow, treeP, new ObjectId[] { B });
+		final ObjectId T = commit(ow, treeT, new ObjectId[] { P });
+
+		ThreeWayMerger twm = MergeStrategy.SIMPLE_TWO_WAY_IN_CORE.newMerger(db);
+		twm.setBase(P);
+		boolean merge = twm.merge(new ObjectId[] { B, T });
+		assertTrue(merge);
+
+		final TreeWalk tw = new TreeWalk(db);
+		tw.setRecursive(true);
+		tw.reset(twm.getResultTreeId());
+
+		assertTrue(tw.next());
+		assertEquals("a", tw.getPathString());
+		assertCorrectId(treeB, tw);
+
+		assertTrue(tw.next());
+		assertEquals("t", tw.getPathString());
+		assertCorrectId(treeT, tw);
+
+		assertFalse(tw.next());
+	}
+
 	private void assertCorrectId(final DirCache treeT, final TreeWalk tw) {
 		assertEquals(treeT.getEntry(tw.getPathString()).getObjectId(), tw
 				.getObjectId(0));