Add some tests for alternates

Change-Id: I00d256d0e132c0b5ff02ff27a26fbf21ecc1bccd
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.test/tst/org/eclipse/jgit/internal/storage/file/AlternatesTest.java

@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2017, Matthias Sohn <matthias.sohn@sap.com>
+ * 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.internal.storage.file;
+
+import static org.junit.Assert.assertTrue;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+
+import org.eclipse.jgit.api.Git;
+import org.eclipse.jgit.api.errors.AbortedByHookException;
+import org.eclipse.jgit.api.errors.ConcurrentRefUpdateException;
+import org.eclipse.jgit.api.errors.GitAPIException;
+import org.eclipse.jgit.api.errors.NoFilepatternException;
+import org.eclipse.jgit.api.errors.NoHeadException;
+import org.eclipse.jgit.api.errors.NoMessageException;
+import org.eclipse.jgit.api.errors.UnmergedPathsException;
+import org.eclipse.jgit.api.errors.WrongRepositoryStateException;
+import org.eclipse.jgit.junit.JGitTestUtil;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.test.resources.SampleDataRepositoryTestCase;
+import org.junit.Test;
+
+public class AlternatesTest extends SampleDataRepositoryTestCase {
+
+	private FileRepository db2;
+
+	@Override
+	public void setUp() throws Exception {
+		super.setUp();
+		db2 = createWorkRepository();
+	}
+
+	private void setAlternate(FileRepository from, FileRepository to)
+			throws IOException {
+		File alt = new File(from.getObjectDatabase().getDirectory(),
+				"info/alternates");
+		alt.getParentFile().mkdirs();
+		File fromDir = from.getObjectDatabase().getDirectory();
+		File toDir = to.getObjectDatabase().getDirectory();
+		Path relative = fromDir.toPath().relativize(toDir.toPath());
+		write(alt, relative.toString() + "\n");
+	}
+
+	@Test
+	public void testAlternate() throws Exception {
+		setAlternate(db2, db);
+		RevCommit c = createCommit();
+		assertCommit(c);
+		assertAlternateObjects(db2);
+	}
+
+	@Test
+	public void testAlternateCyclic2() throws Exception {
+		setAlternate(db2, db);
+		setAlternate(db, db2);
+		RevCommit c = createCommit();
+		assertCommit(c);
+		assertAlternateObjects(db2);
+	}
+
+	@Test
+	public void testAlternateCyclic3() throws Exception {
+		FileRepository db3 = createBareRepository();
+		setAlternate(db2, db3);
+		setAlternate(db3, db);
+		setAlternate(db, db2);
+		RevCommit c = createCommit();
+		assertCommit(c);
+		assertAlternateObjects(db2);
+	}
+
+	private RevCommit createCommit() throws IOException, GitAPIException,
+			NoFilepatternException, NoHeadException, NoMessageException,
+			UnmergedPathsException, ConcurrentRefUpdateException,
+			WrongRepositoryStateException, AbortedByHookException {
+		JGitTestUtil.writeTrashFile(db, "test", "test");
+		Git git = Git.wrap(db2);
+		git.add().addFilepattern("test").call();
+		RevCommit c = git.commit().setMessage("adding test").call();
+		return c;
+	}
+
+	private void assertCommit(RevCommit c) {
+		ObjectDirectory od = db2.getObjectDatabase();
+		assertTrue("can't find expected commit" + c.name(),
+				od.has(c.toObjectId()));
+	}
+
+	private void assertAlternateObjects(FileRepository repo) {
+		// check some objects in alternate
+		final ObjectId alternateObjects[] = new ObjectId[] {
+				ObjectId.fromString("49322bb17d3acc9146f98c97d078513228bbf3c0"),
+				ObjectId.fromString("d0114ab8ac326bab30e3a657a0397578c5a1af88"),
+				ObjectId.fromString("f73b95671f326616d66b2afb3bdfcdbbce110b44"),
+				ObjectId.fromString("6020a3b8d5d636e549ccbd0c53e2764684bb3125"),
+				ObjectId.fromString("0a3d7772488b6b106fb62813c4d6d627918d9181"),
+				ObjectId.fromString("da0f8ed91a8f2f0f067b3bdf26265d5ca48cf82c"),
+				ObjectId.fromString(
+						"cd4bcfc27da62c6b840de700be1c60a7e69952a5") };
+		ObjectDirectory od = repo.getObjectDatabase();
+		for (ObjectId o : alternateObjects) {
+			assertTrue(String.format("can't find object %s in alternate",
+					o.getName()), od.has(o));
+		}
+	}
+}