CommitCommand: Use original author on amend if author is not set

This way, callers don't have to parse author ident of HEAD themselves.

Bug: 362391
Change-Id: I383a817e6ed4707d637c52c007bc7b57728e6c85

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

@@ -48,7 +48,9 @@ import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 import java.io.File;
+import java.util.Date;
 import java.util.List;
+import java.util.TimeZone;
 
 import org.eclipse.jgit.api.errors.WrongRepositoryStateException;
 import org.eclipse.jgit.diff.DiffEntry;
@@ -57,6 +59,7 @@ import org.eclipse.jgit.lib.ConfigConstants;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.FileMode;
 import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.PersonIdent;
 import org.eclipse.jgit.lib.RefUpdate;
 import org.eclipse.jgit.lib.RefUpdate.Result;
 import org.eclipse.jgit.lib.Repository;
@@ -427,4 +430,45 @@ public class CommitCommandTest extends RepositoryTestCase {
 		Git git = new Git(db);
 		git.commit().setAmend(true).setMessage("initial commit").call();
 	}
+
+	@Test
+	public void commitAmendWithoutAuthorShouldSetOriginalAuthorAndAuthorTime()
+			throws Exception {
+		Git git = new Git(db);
+
+		writeTrashFile("file1", "file1");
+		git.add().addFilepattern("file1").call();
+
+		final String authorName = "First Author";
+		final String authorEmail = "author@example.org";
+		final Date authorDate = new Date(1349621117000L);
+		PersonIdent firstAuthor = new PersonIdent(authorName, authorEmail,
+				authorDate, TimeZone.getTimeZone("UTC"));
+		git.commit().setMessage("initial commit").setAuthor(firstAuthor).call();
+
+		RevCommit amended = git.commit().setAmend(true)
+				.setMessage("amend commit").call();
+
+		PersonIdent amendedAuthor = amended.getAuthorIdent();
+		assertEquals(authorName, amendedAuthor.getName());
+		assertEquals(authorEmail, amendedAuthor.getEmailAddress());
+		assertEquals(authorDate.getTime(), amendedAuthor.getWhen().getTime());
+	}
+
+	@Test
+	public void commitAmendWithAuthorShouldUseIt() throws Exception {
+		Git git = new Git(db);
+
+		writeTrashFile("file1", "file1");
+		git.add().addFilepattern("file1").call();
+		git.commit().setMessage("initial commit").call();
+
+		RevCommit amended = git.commit().setAmend(true)
+				.setAuthor("New Author", "newauthor@example.org")
+				.setMessage("amend commit").call();
+
+		PersonIdent amendedAuthor = amended.getAuthorIdent();
+		assertEquals("New Author", amendedAuthor.getName());
+		assertEquals("newauthor@example.org", amendedAuthor.getEmailAddress());
+	}
 }

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

@@ -187,6 +187,8 @@ public class CommitCommand extends GitCommand<RevCommit> {
 					RevCommit[] p = previousCommit.getParents();
 					for (int i = 0; i < p.length; i++)
 						parents.add(0, p[i].getId());
+					if (author == null)
+						author = previousCommit.getAuthorIdent();
 				} else {
 					parents.add(0, headId);
 				}
@@ -471,7 +473,7 @@ public class CommitCommand extends GitCommand<RevCommit> {
 	private void processOptions(RepositoryState state) throws NoMessageException {
 		if (committer == null)
 			committer = new PersonIdent(repo);
-		if (author == null)
+		if (author == null && !amend)
 			author = committer;
 
 		// when doing a merge commit parse MERGE_HEAD and MERGE_MSG files
@@ -574,7 +576,8 @@ public class CommitCommand extends GitCommand<RevCommit> {
 	/**
 	 * Sets the author for this {@code commit}. If no author is explicitly
 	 * specified because this method is never called or called with {@code null}
-	 * value then the author will be set to the committer.
+	 * value then the author will be set to the committer or to the original
+	 * author when amending.
 	 *
 	 * @param author
 	 *            the author used for the {@code commit}
@@ -589,7 +592,8 @@ public class CommitCommand extends GitCommand<RevCommit> {
 	/**
 	 * Sets the author for this {@code commit}. If no author is explicitly
 	 * specified because this method is never called or called with {@code null}
-	 * value then the author will be set to the committer.
+	 * value then the author will be set to the committer or to the original
+	 * author when amending.
 	 *
 	 * @param name
 	 *            the name of the author used for the {@code commit}