Allow detecting which files were renamed during a revwalk

The egit history view shows the files associated with a commit by using
a PathFilter. When following renames with a FollowFilter, the PathFilter
cannot be configured anymore because the affected files are simply not
known.

Thus, it should be possible to get to know which files are renamed.

Bug: 302549
Change-Id: I4761e9f5cfb4f0ef0b0e1e38991401a1d5003bea

2 files changed, 179 insertions, 0 deletions

diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkFollowFilterTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkFollowFilterTest.java
new file mode 100644
index 0000000000..1f70a71a11
--- /dev/null
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkFollowFilterTest.java
@@ -0,0 +1,173 @@
+/*
+ * Copyright (C) 2011, GEBIT Solutions
+ * 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.revwalk;
+
+import static org.junit.Assert.assertNull;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.eclipse.jgit.diff.DiffEntry;
+import org.eclipse.jgit.junit.TestRepository.CommitBuilder;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+public class RevWalkFollowFilterTest extends RevWalkTestCase {
+
+	private static class DiffCollector extends RenameCallback {
+		List<DiffEntry> diffs = new ArrayList<DiffEntry>();
+
+		@Override
+		public void renamed(DiffEntry diff) {
+			diffs.add(diff);
+		}
+	}
+
+	private DiffCollector diffCollector;
+
+	@Before
+	@Override
+	public void setUp() throws Exception {
+		super.setUp();
+		diffCollector = new DiffCollector();
+	}
+
+	protected FollowFilter follow(final String followPath) {
+		FollowFilter followFilter = FollowFilter.create(followPath);
+		followFilter.setRenameCallback(diffCollector);
+		rw.setTreeFilter(followFilter);
+		return followFilter;
+	}
+
+	@Test
+	public void testNoRename() throws Exception {
+		final RevCommit a = commit(tree(file("0", blob("0"))));
+		follow("0");
+		markStart(a);
+		assertCommit(a, rw.next());
+		assertNull(rw.next());
+
+		assertNoRenames();
+	}
+
+	@Test
+	public void testSingleRename() throws Exception {
+		final RevCommit a = commit(tree(file("a", blob("A"))));
+
+		// rename a to b
+		CommitBuilder commitBuilder = commitBuilder().parent(a)
+				.add("b", blob("A")).rm("a");
+		RevCommit renameCommit = commitBuilder.create();
+
+		follow("b");
+		markStart(renameCommit);
+		assertCommit(renameCommit, rw.next());
+		assertCommit(a, rw.next());
+		assertNull(rw.next());
+
+		assertRenames("a->b");
+	}
+
+	@Test
+	public void testMultiRename() throws Exception {
+		final String contents = "A";
+		final RevCommit a = commit(tree(file("a", blob(contents))));
+
+		// rename a to b
+		CommitBuilder commitBuilder = commitBuilder().parent(a)
+				.add("b", blob(contents)).rm("a");
+		RevCommit renameCommit1 = commitBuilder.create();
+
+		// rename b to c
+		commitBuilder = commitBuilder().parent(renameCommit1)
+				.add("c", blob(contents)).rm("b");
+		RevCommit renameCommit2 = commitBuilder.create();
+
+		// rename c to a
+		commitBuilder = commitBuilder().parent(renameCommit2)
+				.add("a", blob(contents)).rm("c");
+		RevCommit renameCommit3 = commitBuilder.create();
+
+		follow("a");
+		markStart(renameCommit3);
+		assertCommit(renameCommit3, rw.next());
+		assertCommit(renameCommit2, rw.next());
+		assertCommit(renameCommit1, rw.next());
+		assertCommit(a, rw.next());
+		assertNull(rw.next());
+
+		assertRenames("c->a", "b->c", "a->b");
+	}
+
+	/**
+	 * Assert which renames should have happened, in traversal order.
+	 * @param expectedRenames
+	 *            the rename specs, each one in the form "srcPath->destPath"
+	 */
+	protected void assertRenames(String... expectedRenames) {
+		Assert.assertEquals("Unexpected number of renames. Expected: " +
+				expectedRenames.length + ", actual: " + diffCollector.diffs.size(),
+				expectedRenames.length, diffCollector.diffs.size());
+
+		for (int i = 0; i < expectedRenames.length; i++) {
+			DiffEntry diff = diffCollector.diffs.get(i);
+			Assert.assertNotNull(diff);
+			String[] split = expectedRenames[i].split("->");
+
+			Assert.assertNotNull(split);
+			Assert.assertEquals(2, split.length);
+			String src = split[0];
+			String target = split[1];
+
+			Assert.assertEquals(src, diff.getOldPath());
+			Assert.assertEquals(target, diff.getNewPath());
+		}
+	}
+
+	protected void assertNoRenames() {
+		Assert.assertEquals("Found unexpected rename/copy diff", 0,
+				diffCollector.diffs.size());
+	}
+
+}
diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkTestCase.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkTestCase.java
index 1e05e53cb5..20341eef61 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkTestCase.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/revwalk/RevWalkTestCase.java
@@ -49,6 +49,7 @@ import java.util.Date;
 
 import org.eclipse.jgit.dircache.DirCacheEntry;
 import org.eclipse.jgit.junit.TestRepository;
+import org.eclipse.jgit.junit.TestRepository.CommitBuilder;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.RepositoryTestCase;
 
@@ -119,6 +120,11 @@ public abstract class RevWalkTestCase extends RepositoryTestCase {
 		return util.tag(name, dst);
 	}
 
+	protected CommitBuilder commitBuilder()
+			throws Exception {
+		return util.commit();
+	}
+
 	protected <T extends RevObject> T parseBody(final T t) throws Exception {
 		return util.parseBody(t);
 	}