Only fetch tags that do not exist locally with auto-follow

This corresponds to what C Git does, quoting from the fetch man page:

  This is done by first fetching from the remote using the given
  <refspec>s, and if the repository has objects that are pointed by
  remote tags that it does not yet have, then fetch those missing tags.

Before, JGit would also fetch tags that exist locally but point to a
different object, resulting in REJECTED results for these.

Also add some test cases to cover more cases.

Bug: 388095
Change-Id: Ib03d2d82e9c4b60179d626cfd5174be1da6388b2
Also-by: Stefan Lay <stefan.lay@sap.com>

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

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2010, Chris Aniszczyk <caniszczyk@gmail.com>
+ * Copyright (C) 2010, 2013 Chris Aniszczyk <caniszczyk@gmail.com>
  * and other copyright owners as documented in the project's IP log.
  *
  * This program and the accompanying materials are made available
@@ -43,55 +43,129 @@
 package org.eclipse.jgit.api;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
 
 import java.io.IOException;
 import java.net.URISyntaxException;
+import java.util.Collection;
 
 import org.eclipse.jgit.api.errors.GitAPIException;
 import org.eclipse.jgit.api.errors.JGitInternalException;
 import org.eclipse.jgit.junit.RepositoryTestCase;
+import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.lib.StoredConfig;
 import org.eclipse.jgit.revwalk.RevCommit;
+import org.eclipse.jgit.transport.FetchResult;
 import org.eclipse.jgit.transport.RefSpec;
 import org.eclipse.jgit.transport.RemoteConfig;
+import org.eclipse.jgit.transport.TagOpt;
+import org.eclipse.jgit.transport.TrackingRefUpdate;
 import org.eclipse.jgit.transport.URIish;
+import org.junit.Before;
 import org.junit.Test;
 
 public class FetchCommandTest extends RepositoryTestCase {
 
-	@Test
-	public void testFetch() throws JGitInternalException, IOException,
-			GitAPIException, URISyntaxException {
+	private Git git;
+	private Git remoteGit;
+
+	@Before
+	public void setupRemoteRepository() throws IOException, URISyntaxException {
+		git = new Git(db);
 
 		// create other repository
-		Repository db2 = createWorkRepository();
-		Git git2 = new Git(db2);
+		Repository remoteRepository = createWorkRepository();
+		remoteGit = new Git(remoteRepository);
 
 		// setup the first repository to fetch from the second repository
 		final StoredConfig config = db.getConfig();
 		RemoteConfig remoteConfig = new RemoteConfig(config, "test");
-		URIish uri = new URIish(db2.getDirectory().toURI().toURL());
+		URIish uri = new URIish(remoteRepository.getDirectory().toURI().toURL());
 		remoteConfig.addURI(uri);
 		remoteConfig.update(config);
 		config.save();
+	}
 
-		// create some refs via commits and tag
-		RevCommit commit = git2.commit().setMessage("initial commit").call();
-		Ref tagRef = git2.tag().setName("tag").call();
+	@Test
+	public void testFetch() throws JGitInternalException, IOException,
+			GitAPIException {
 
-		Git git1 = new Git(db);
+		// create some refs via commits and tag
+		RevCommit commit = remoteGit.commit().setMessage("initial commit").call();
+		Ref tagRef = remoteGit.tag().setName("tag").call();
 
 		RefSpec spec = new RefSpec("refs/heads/master:refs/heads/x");
-		git1.fetch().setRemote("test").setRefSpecs(spec)
+		git.fetch().setRemote("test").setRefSpecs(spec)
 				.call();
 
 		assertEquals(commit.getId(),
 				db.resolve(commit.getId().getName() + "^{commit}"));
 		assertEquals(tagRef.getObjectId(),
 				db.resolve(tagRef.getObjectId().getName()));
+	}
+
+	@Test
+	public void fetchShouldAutoFollowTag() throws Exception {
+		remoteGit.commit().setMessage("commit").call();
+		Ref tagRef = remoteGit.tag().setName("foo").call();
+
+		RefSpec spec = new RefSpec("refs/heads/*:refs/remotes/origin/*");
+		git.fetch().setRemote("test").setRefSpecs(spec)
+				.setTagOpt(TagOpt.AUTO_FOLLOW).call();
 
+		assertEquals(tagRef.getObjectId(), db.resolve("foo"));
 	}
 
+	@Test
+	public void fetchShouldAutoFollowTagForFetchedObjects() throws Exception {
+		remoteGit.commit().setMessage("commit").call();
+		Ref tagRef = remoteGit.tag().setName("foo").call();
+		remoteGit.commit().setMessage("commit2").call();
+		RefSpec spec = new RefSpec("refs/heads/*:refs/remotes/origin/*");
+		git.fetch().setRemote("test").setRefSpecs(spec)
+				.setTagOpt(TagOpt.AUTO_FOLLOW).call();
+		assertEquals(tagRef.getObjectId(), db.resolve("foo"));
+	}
+
+	@Test
+	public void fetchShouldNotFetchTagsFromOtherBranches() throws Exception {
+		remoteGit.commit().setMessage("commit").call();
+		remoteGit.checkout().setName("other").setCreateBranch(true).call();
+		remoteGit.commit().setMessage("commit2").call();
+		remoteGit.tag().setName("foo").call();
+		RefSpec spec = new RefSpec(
+				"refs/heads/master:refs/remotes/origin/master");
+		git.fetch().setRemote("test").setRefSpecs(spec)
+				.setTagOpt(TagOpt.AUTO_FOLLOW).call();
+		assertNull(db.resolve("foo"));
+	}
+
+	@Test
+	public void fetchWithUpdatedTagShouldNotTryToUpdateLocal() throws Exception {
+		final String tagName = "foo";
+		remoteGit.commit().setMessage("commit").call();
+		Ref tagRef = remoteGit.tag().setName(tagName).call();
+		ObjectId originalId = tagRef.getObjectId();
+
+		RefSpec spec = new RefSpec("refs/heads/*:refs/remotes/origin/*");
+		git.fetch().setRemote("test").setRefSpecs(spec)
+				.setTagOpt(TagOpt.AUTO_FOLLOW).call();
+		assertEquals(originalId, db.resolve(tagName));
+
+		remoteGit.commit().setMessage("commit 2").call();
+		remoteGit.tag().setName(tagName).setForceUpdate(true).call();
+
+		FetchResult result = git.fetch().setRemote("test").setRefSpecs(spec)
+				.setTagOpt(TagOpt.AUTO_FOLLOW).call();
+
+		Collection<TrackingRefUpdate> refUpdates = result
+				.getTrackingRefUpdates();
+		assertEquals(1, refUpdates.size());
+		TrackingRefUpdate update = refUpdates.iterator().next();
+		assertEquals("refs/heads/master", update.getRemoteName());
+
+		assertEquals(originalId, db.resolve(tagName));
+	}
 }

org.eclipse.jgit/src/org/eclipse/jgit/transport/FetchProcess.java

@@ -382,23 +382,16 @@ class FetchProcess {
 				continue;
 
 			Ref local = haveRefs.get(r.getName());
-			ObjectId obj = r.getObjectId();
-
-			if (r.getPeeledObjectId() == null) {
-				if (local != null && obj.equals(local.getObjectId()))
-					continue;
-				if (askFor.containsKey(obj) || transport.local.hasObject(obj))
-					wantTag(r);
-				else
-					additionalTags.add(r);
+			if (local != null)
+				// We already have a tag with this name, don't fetch it (even if
+				// the local is different).
 				continue;
-			}
 
-			if (local != null) {
-				if (!obj.equals(local.getObjectId()))
-					wantTag(r);
-			} else if (askFor.containsKey(r.getPeeledObjectId())
-					|| transport.local.hasObject(r.getPeeledObjectId()))
+			ObjectId obj = r.getPeeledObjectId();
+			if (obj == null)
+				obj = r.getObjectId();
+
+			if (askFor.containsKey(obj) || transport.local.hasObject(obj))
 				wantTag(r);
 			else
 				additionalTags.add(r);