Ensure that cli options specified with action=Highlander can only be …

…set once, even if the set value is a default value. Add tests for action=Highlander. See borgbackup#7500 borgbackup#6269

src/borg/archiver/_common.py

@@ -249,9 +249,37 @@ def wrapper(self, args, repository, manifest, **kwargs):
 class Highlander(argparse.Action):
     """make sure some option is only given once"""
 
+    def __init__(
+        self,
+        option_strings,
+        dest,
+        nargs=None,
+        const=None,
+        default=None,
+        type=None,
+        choices=None,
+        required=False,
+        help=None,
+        metavar=None,
+    ):
+        self.called = False
+        super(Highlander, self).__init__(
+            option_strings=option_strings,
+            dest=dest,
+            nargs=nargs,
+            const=const,
+            default=default,
+            type=type,
+            choices=choices,
+            required=required,
+            help=help,
+            metavar=metavar,
+        )
+
     def __call__(self, parser, namespace, values, option_string=None):
-        if getattr(namespace, self.dest, None) != self.default:
+        if self.called:
             raise argparse.ArgumentError(self, "There can be only one.")
+        self.called = True
         setattr(namespace, self.dest, values)
 
 

src/borg/testsuite/archiver/argparsing.py

@@ -1,8 +1,9 @@
 import argparse
 import pytest
+from itertools import combinations_with_replacement
 
 from ...helpers import parse_storage_quota
-from . import ArchiverTestCaseBase, Archiver, RK_ENCRYPTION
+from . import ArchiverTestCaseBase, Archiver, RK_ENCRYPTION, src_dir
 
 
 class ArchiverTestCase(ArchiverTestCaseBase):
@@ -11,6 +12,23 @@ def test_bad_filters(self):
         self.cmd(f"--repo={self.repository_location}", "create", "test", "input")
         self.cmd(f"--repo={self.repository_location}", "delete", "--first", "1", "--last", "1", fork=True, exit_code=2)
 
+    def test_highlander(self):
+        self.cmd(f"--repo={self.repository_location}", "rcreate", RK_ENCRYPTION)
+        self.cmd(f"--repo={self.repository_location}", "create", "--comment", "comment 1", "test-1", src_dir)
+        error_msg = "There can be only one"
+        # Default permission is 077
+        # Test that it works with a oen time specified default or custom value
+        output_default = self.cmd(f"--repo={self.repository_location}", "--umask", "077", "rlist")
+        assert error_msg not in output_default
+        output_custom = self.cmd(f"--repo={self.repository_location}", "--umask", "007", "rlist")
+        assert error_msg not in output_custom
+        # Test that all combinations of custom and default permissions fail
+        for first, second in combinations_with_replacement(["007", "077"], 2):
+            output_custom = self.cmd(
+                f"--repo={self.repository_location}", "--umask", first, "--umask", second, "rlist", exit_code=2
+            )
+            assert error_msg in output_custom
+
 
 def test_get_args():
     archiver = Archiver()