Allow checkout paths without specifying branch name

JGit CLI should allow to do this: checkout -- <path>

Currently, even if "a" is a valid path in the git repo, jgit CLI can't
checkout it:
$jgit checkout -- a
error: pathspec 'a' did not match any file(s) known to git.

The fix also fixes at same time "unnamed" zombie "[VAL ...]" argument
shown on the command line.

Before fix:
$jgit -h
jgit checkout name [VAL ...] [-- path ... ...] [--force (-f)] [--help
(-h)] [--orphan] [-b]

After fix:
$jgit -h
jgit checkout [name] [-- path ... ...] [--force (-f)] [--help (-h)]
[--orphan] [-b]

Bug: 475765
Change-Id: I2b0e77959a72e4aac68452dc3846adaa745b0831
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>

1 files changed, 37 insertions, 0 deletions

diff --git a/org.eclipse.jgit.pgm.test/tst/org/eclipse/jgit/pgm/CheckoutTest.java b/org.eclipse.jgit.pgm.test/tst/org/eclipse/jgit/pgm/CheckoutTest.java
index 939a9f6fdd..167d8ab512 100644
--- a/org.eclipse.jgit.pgm.test/tst/org/eclipse/jgit/pgm/CheckoutTest.java
+++ b/org.eclipse.jgit.pgm.test/tst/org/eclipse/jgit/pgm/CheckoutTest.java
@@ -44,9 +44,14 @@ package org.eclipse.jgit.pgm;
 
 import static org.junit.Assert.assertArrayEquals;
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertTrue;
 
 import java.io.File;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Arrays;
 import java.util.List;
 
 import org.eclipse.jgit.api.Git;
@@ -59,7 +64,9 @@ import org.eclipse.jgit.revwalk.RevCommit;
 import org.eclipse.jgit.treewalk.FileTreeIterator;
 import org.eclipse.jgit.treewalk.FileTreeIterator.FileEntry;
 import org.eclipse.jgit.treewalk.TreeWalk;
+import org.eclipse.jgit.util.FS;
 import org.eclipse.jgit.util.FileUtils;
+import org.junit.Assume;
 import org.junit.Test;
 
 public class CheckoutTest extends CLIRepositoryTestCase {
@@ -578,4 +585,34 @@ public class CheckoutTest extends CLIRepositoryTestCase {
 				execute("git branch"));
 		assertEquals("Hello world b", read(b));
 	}
+
+	@Test
+	public void testCheckouSingleFile() throws Exception {
+		try (Git git = new Git(db)) {
+			File a = writeTrashFile("a", "file a");
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("commit file a").call();
+			writeTrashFile("a", "b");
+			assertEquals("b", read(a));
+			assertEquals("[]", Arrays.toString(execute("git checkout -- a")));
+			assertEquals("file a", read(a));
+		}
+	}
+
+	@Test
+	public void testCheckoutLink() throws Exception {
+		Assume.assumeTrue(FS.DETECTED.supportsSymlinks());
+		try (Git git = new Git(db)) {
+			Path path = writeLink("a", "link_a");
+			assertTrue(Files.isSymbolicLink(path));
+			git.add().addFilepattern(".").call();
+			git.commit().setMessage("commit link a").call();
+			deleteTrashFile("a");
+			writeTrashFile("a", "Hello world a");
+			assertFalse(Files.isSymbolicLink(path));
+			assertEquals("[]", Arrays.toString(execute("git checkout -- a")));
+			assertEquals("link_a", FileUtils.readSymLink(path.toFile()));
+			assertTrue(Files.isSymbolicLink(path));
+		}
+	}
 }