reintroduce find subcommand

the `last` symlink no longer exists, so we need another way to easily
get the latest revision in external scripts

changelog.d/20231207_235814_jb_reintroduce_find.rst

@@ -0,0 +1,3 @@
+.. A new scriv changelog fragment.
+
+- reintroduce `find` subcommand

src/backy/main.py

@@ -105,6 +105,13 @@ def restore(self, revision, target):
         b = backy.backup.Backup(self.path, self.log)
         b.restore(revision, target)
 
+    def find(self, revision, uuid):
+        b = backy.backup.Backup(self.path, self.log)
+        if uuid:
+            print(b.find(revision).uuid)
+        else:
+            print(b.find(revision).filename)
+
     def forget(self, revision):
         b = backy.backup.Backup(self.path, self.log)
         b.forget_revision(revision)
@@ -305,6 +312,25 @@ def setup_argparser():
     )
     p.set_defaults(func="purge")
 
+    # FIND
+    p = subparsers.add_parser(
+        "find",
+        help="Print full path to a given revision's image file",
+    )
+    p.add_argument(
+        "--uuid",
+        action="store_true",
+        help="Print uuid instead of full path",
+    )
+    p.add_argument(
+        "-r",
+        "--revision",
+        metavar="SPEC",
+        default="latest",
+        help="use revision SPEC to find",
+    )
+    p.set_defaults(func="find")
+
     # STATUS
     p = subparsers.add_parser(
         "status",

src/backy/tests/test_main.py

@@ -29,7 +29,7 @@ def test_display_usage(capsys, argv):
     assert (
         """\
 usage: pytest [-h] [-v] [-l LOGFILE] [-b BACKUPDIR]
-              {client,backup,restore,purge,status,\
+              {client,backup,restore,purge,find,status,\
 upgrade,scheduler,distrust,verify,forget}
               ...
 """
@@ -64,7 +64,7 @@ def test_display_help(capsys, argv):
         Ellipsis(
             """\
 usage: pytest [-h] [-v] [-l LOGFILE] [-b BACKUPDIR]
-              {client,backup,restore,purge,status,\
+              {client,backup,restore,purge,find,status,\
 upgrade,scheduler,distrust,verify,forget}
               ...
 
@@ -198,6 +198,36 @@ def test_call_backup(tmpdir, capsys, argv, monkeypatch):
     assert exit.value.code == 0
 
 
+def test_call_find(capsys, backup, argv, monkeypatch):
+    monkeypatch.setattr(backy.main.Command, "find", print_args)
+    argv.extend(["-v", "-b", backup.path, "find", "-r", "1"])
+    utils.log_data = ""
+    with pytest.raises(SystemExit) as exit:
+        backy.main.main()
+    assert exit.value.code == 0
+    out, err = capsys.readouterr()
+    assert (
+        Ellipsis(
+            """\
+(<backy.main.Command object at ...>,)
+{'revision': '1', 'uuid': False}
+"""
+        )
+        == out
+    )
+    assert (
+        Ellipsis(
+            """\
+... D command/invoked                args='... -v -b ... find -r 1'
+... D command/parsed                 func='find' func_args={'uuid': False, 'revision': '1'}
+... D command/successful             \n\
+"""
+        )
+        == utils.log_data
+    )
+    assert exit.value.code == 0
+
+
 @pytest.mark.parametrize(
     ["action", "args"],
     [