Fix ClassCastException in MergeCommand

Test was added which reproduce the ClassCastException when ours or
theirs merge strategy is set to MergeCommand. Merger and MergeCommand
were updated in order to avoid exception.

Change-Id: I4c1284b4e80d82638d0677a05e5d38182526d196
Signed-off-by: Denys Digtiar <duemir@gmail.com>
Signed-off-by: Chris Aniszczyk <caniszczyk@gmail.com>

org.eclipse.jgit.test/META-INF/MANIFEST.MF

@@ -38,9 +38,11 @@ Import-Package: org.eclipse.jgit;version="[1.1.0,1.2.0)",
  org.eclipse.jgit.treewalk.filter;version="[1.1.0,1.2.0)",
  org.eclipse.jgit.util;version="[1.1.0,1.2.0)",
  org.eclipse.jgit.util.io;version="[1.1.0,1.2.0)",
- org.junit;version="[4.0.0,5.0.0)",
  org.hamcrest.core;version="[1.1.0,2.0.0)",
- org.hamcrest;version="[1.1.0,2.0.0)"
+ org.hamcrest;version="[1.1.0,2.0.0)",
+ org.junit;version="[4.4.0,5.0.0)",
+ org.junit.runner;version="[4.4.0,5.0.0)",
+ org.junit.experimental.theories;version="[4.4.0,5.0.0)"
 Require-Bundle: com.jcraft.jsch;bundle-version="[0.1.37,0.2.0)"
 Export-Package: org.eclipse.jgit.lib
  

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

@@ -62,8 +62,17 @@ import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.util.FileUtils;
 import org.junit.Test;
+import org.junit.experimental.theories.DataPoints;
+import org.junit.experimental.theories.Theories;
+import org.junit.experimental.theories.Theory;
+import org.junit.runner.RunWith;
 
+@RunWith(Theories.class)
 public class MergeCommandTest extends RepositoryTestCase {
+
+	public static @DataPoints
+	MergeStrategy[] mergeStrategies = MergeStrategy.get();
+
 	@Test
 	public void testMergeInItself() throws Exception {
 		Git git = new Git(db);
@@ -161,6 +170,28 @@ public class MergeCommandTest extends RepositoryTestCase {
 		}
 	}
 
+	@Theory
+	public void testMergeSuccessAllStrategies(MergeStrategy mergeStrategy)
+			throws Exception {
+		Git git = new Git(db);
+
+		RevCommit first = git.commit().setMessage("first").call();
+		createBranch(first, "refs/heads/side");
+
+		writeTrashFile("a", "a");
+		git.add().addFilepattern("a").call();
+		git.commit().setMessage("second").call();
+
+		checkoutBranch("refs/heads/side");
+		writeTrashFile("b", "b");
+		git.add().addFilepattern("b").call();
+		git.commit().setMessage("third").call();
+
+		MergeResult result = git.merge().setStrategy(mergeStrategy)
+				.include(db.getRef(Constants.MASTER)).call();
+		assertEquals(MergeStatus.MERGED, result.getMergeStatus());
+	}
+
 	@Test
 	public void testContentMerge() throws Exception {
 		Git git = new Git(db);

org.eclipse.jgit/src/org/eclipse/jgit/api/MergeCommand.java

@@ -71,9 +71,9 @@ import org.eclipse.jgit.lib.RefUpdate.Result;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.merge.MergeMessageFormatter;
 import org.eclipse.jgit.merge.MergeStrategy;
+import org.eclipse.jgit.merge.Merger;
 import org.eclipse.jgit.merge.ResolveMerger;
 import org.eclipse.jgit.merge.ResolveMerger.MergeFailureReason;
-import org.eclipse.jgit.merge.ThreeWayMerger;
 import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.revwalk.RevWalk;
 import org.eclipse.jgit.treewalk.FileTreeIterator;
@@ -193,8 +193,7 @@ public class MergeCommand extends GitCommand<MergeResult> {
 						commits, head);
 				repo.writeMergeCommitMsg(mergeMessage);
 				repo.writeMergeHeads(Arrays.asList(ref.getObjectId()));
-				ThreeWayMerger merger = (ThreeWayMerger) mergeStrategy
-						.newMerger(repo);
+				Merger merger = mergeStrategy.newMerger(repo);
 				boolean noProblems;
 				Map<String, org.eclipse.jgit.merge.MergeResult<?>> lowLevelResults = null;
 				Map<String, MergeFailureReason> failingPaths = null;

org.eclipse.jgit/src/org/eclipse/jgit/merge/Merger.java

@@ -134,7 +134,7 @@ public abstract class Merger {
 	 *             one or more sources could not be read, or outputs could not
 	 *             be written to the Repository.
 	 */
-	public boolean merge(final AnyObjectId[] tips) throws IOException {
+	public boolean merge(final AnyObjectId... tips) throws IOException {
 		sourceObjects = new RevObject[tips.length];
 		for (int i = 0; i < tips.length; i++)
 			sourceObjects[i] = walk.parseAny(tips[i]);

org.eclipse.jgit/src/org/eclipse/jgit/merge/ThreeWayMerger.java

@@ -84,7 +84,7 @@ public abstract class ThreeWayMerger extends Merger {
 	 * @param id
 	 *            common base treeish; null to automatically compute the common
 	 *            base from the input commits during
-	 *            {@link #merge(AnyObjectId, AnyObjectId)}.
+	 *            {@link #merge(AnyObjectId...)}.
 	 * @throws IncorrectObjectTypeException
 	 *             the object is not a treeish.
 	 * @throws MissingObjectException
@@ -101,33 +101,8 @@ public abstract class ThreeWayMerger extends Merger {
 		}
 	}
 
-	/**
-	 * Merge together two tree-ish objects.
-	 * <p>
-	 * Any tree-ish may be supplied as inputs. Commits and/or tags pointing at
-	 * trees or commits may be passed as input objects.
-	 *
-	 * @param a
-	 *            source tree to be combined together.
-	 * @param b
-	 *            source tree to be combined together.
-	 * @return true if the merge was completed without conflicts; false if the
-	 *         merge strategy cannot handle this merge or there were conflicts
-	 *         preventing it from automatically resolving all paths.
-	 * @throws IncorrectObjectTypeException
-	 *             one of the input objects is not a commit, but the strategy
-	 *             requires it to be a commit.
-	 * @throws IOException
-	 *             one or more sources could not be read, or outputs could not
-	 *             be written to the Repository.
-	 */
-	public boolean merge(final AnyObjectId a, final AnyObjectId b)
-			throws IOException {
-		return merge(new AnyObjectId[] { a, b });
-	}
-
 	@Override
-	public boolean merge(final AnyObjectId[] tips) throws IOException {
+	public boolean merge(final AnyObjectId... tips) throws IOException {
 		if (tips.length != 2)
 			return false;
 		return super.merge(tips);

org.eclipse.jgit/src/org/eclipse/jgit/notes/NoteMapMerger.java

@@ -55,7 +55,6 @@ import org.eclipse.jgit.lib.ObjectReader;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.merge.MergeStrategy;
 import org.eclipse.jgit.merge.Merger;
-import org.eclipse.jgit.merge.ThreeWayMergeStrategy;
 import org.eclipse.jgit.merge.ThreeWayMerger;
 import org.eclipse.jgit.treewalk.AbstractTreeIterator;
 import org.eclipse.jgit.treewalk.TreeWalk;
@@ -323,23 +322,13 @@ public class NoteMapMerger {
 		ObjectId theirsId = write(theirsList);
 		inserter.flush();
 
-		ObjectId resultTreeId;
-		if (nonNotesMergeStrategy instanceof ThreeWayMergeStrategy) {
-			ThreeWayMerger m = ((ThreeWayMergeStrategy) nonNotesMergeStrategy)
-					.newMerger(db, true);
-			m.setBase(baseId);
-			if (!m.merge(oursId, theirsId))
-				throw new NotesMergeConflictException(baseList, oursList,
-						theirsList);
-
-			resultTreeId = m.getResultTreeId();
-		} else {
-			Merger m = nonNotesMergeStrategy.newMerger(db, true);
-			if (!m.merge(new AnyObjectId[] { oursId, theirsId }))
-				throw new NotesMergeConflictException(baseList, oursList,
-						theirsList);
-			resultTreeId = m.getResultTreeId();
-		}
+		Merger m = nonNotesMergeStrategy.newMerger(db, true);
+		if (m instanceof ThreeWayMerger)
+			((ThreeWayMerger) m).setBase(baseId);
+		if (!m.merge(oursId, theirsId))
+			throw new NotesMergeConflictException(baseList, oursList,
+					theirsList);
+		ObjectId resultTreeId = m.getResultTreeId();
 		AbbreviatedObjectId none = AbbreviatedObjectId.fromString("");
 		return NoteParser.parse(none, resultTreeId, reader).nonNotes;
 	}