DescribeCommand: Support the "always" option

See:

https://git-scm.com/docs/git-describe#Documentation/git-describe.txt---always

Extend the tests accordingly.

Change-Id: Ibfcda338a246c8cba0df6b6e7b9bad76c9f8b593
Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>

1 files changed, 23 insertions, 2 deletions

diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java b/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java
index 659812450a..db3a3d947d 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/api/DescribeCommand.java
@@ -112,6 +112,11 @@ public class DescribeCommand extends GitCommand<String> {
 	private boolean useTags;
 
 	/**
+	 * Whether to show a uniquely abbreviated commit hash as a fallback or not.
+	 */
+	private boolean always;
+
+	/**
 	 * Constructor for DescribeCommand.
 	 *
 	 * @param repo
@@ -197,6 +202,21 @@ public class DescribeCommand extends GitCommand<String> {
 		return this;
 	}
 
+	/**
+	 * Always describe the commit by eventually falling back to a uniquely
+	 * abbreviated commit hash if no other name matches.
+	 *
+	 * @param always
+	 *            <code>true</code> enables falling back to a uniquely
+	 *            abbreviated commit hash
+	 * @return {@code this}
+	 * @since 5.4
+	 */
+	public DescribeCommand setAlways(boolean always) {
+		this.always = always;
+		return this;
+	}
+
 	private String longDescription(Ref tag, int depth, ObjectId tip)
 			throws IOException {
 		return String.format(
@@ -399,8 +419,9 @@ public class DescribeCommand extends GitCommand<String> {
 			}
 
 			// if all the nodes are dominated by all the tags, the walk stops
-			if (candidates.isEmpty())
-				return null;
+			if (candidates.isEmpty()) {
+				return always ? w.getObjectReader().abbreviate(target).name() : null;
+			}
 
 			Candidate best = Collections.min(candidates,
 					(Candidate o1, Candidate o2) -> o1.depth - o2.depth);