From babefe7eb27e451b48b0f1d4b08633b2a6daa8ef Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 7 Jul 2026 10:48:40 +0000
Subject: [PATCH 1/4] Initial plan


From 420df7e938c524e384a449396fcf5a08681dd2af Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 7 Jul 2026 10:51:21 +0000
Subject: [PATCH 2/4] fix keypaths separator validation and test coverage

---
 benedict/core/keypaths.py   | 5 +++--
 tests/core/test_keypaths.py | 6 ++----
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/benedict/core/keypaths.py b/benedict/core/keypaths.py
index ca4c9dea..5a0a2295 100644
--- a/benedict/core/keypaths.py
+++ b/benedict/core/keypaths.py
@@ -13,8 +13,9 @@ def keypaths(
     indexes: bool = False,
     sort: bool = True,
 ) -> list[str]:
-    separator = separator or "."
-    if not type_util.is_string(separator):
+    if separator is None:
+        separator = "."
+    if not type_util.is_string(separator) or separator == "":
         raise ValueError("separator argument must be a (non-empty) string.")
     kls = keylists(d, indexes=indexes)
     kps = [separator.join([f"{key}" for key in kl]) for kl in kls]
diff --git a/tests/core/test_keypaths.py b/tests/core/test_keypaths.py
index 5d4faa6f..ceb7afc7 100644
--- a/tests/core/test_keypaths.py
+++ b/tests/core/test_keypaths.py
@@ -106,7 +106,7 @@ def test_keypaths_with_invalid_separator(self) -> None:
         with self.assertRaises(ValueError):
             _ = _keypaths(i, separator=True)  # type: ignore[arg-type]
 
-    def test_keypaths_without_separator(self) -> None:
+    def test_keypaths_with_none_separator(self) -> None:
         i = {
             "a": 1,
             "b": {
@@ -120,9 +120,7 @@ def test_keypaths_without_separator(self) -> None:
                 },
             },
         }
-        # with self.assertRaises(ValueError):
-        #     o = _keypaths(i, separator=None)
-        o = _keypaths(i)
+        o = _keypaths(i, separator=None)
         r = [
             "a",
             "b",

From 0a3d3909a98a4eea0190e3e6032fcd693eaef923 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 7 Jul 2026 10:52:19 +0000
Subject: [PATCH 3/4] refine keypaths separator validation

---
 benedict/core/keypaths.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/benedict/core/keypaths.py b/benedict/core/keypaths.py
index 5a0a2295..ce9a25c1 100644
--- a/benedict/core/keypaths.py
+++ b/benedict/core/keypaths.py
@@ -15,7 +15,7 @@ def keypaths(
 ) -> list[str]:
     if separator is None:
         separator = "."
-    if not type_util.is_string(separator) or separator == "":
+    if not type_util.is_string(separator) or not separator:
         raise ValueError("separator argument must be a (non-empty) string.")
     kls = keylists(d, indexes=indexes)
     kps = [separator.join([f"{key}" for key in kl]) for kl in kls]

From c248664df06b9b3f0b4061415a06607a7917ec7b Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 7 Jul 2026 10:53:05 +0000
Subject: [PATCH 4/4] finalize keypaths separator check

---
 benedict/core/keypaths.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/benedict/core/keypaths.py b/benedict/core/keypaths.py
index ce9a25c1..6634cab8 100644
--- a/benedict/core/keypaths.py
+++ b/benedict/core/keypaths.py
@@ -15,7 +15,7 @@ def keypaths(
 ) -> list[str]:
     if separator is None:
         separator = "."
-    if not type_util.is_string(separator) or not separator:
+    if not type_util.is_string(separator) or len(separator) == 0:
         raise ValueError("separator argument must be a (non-empty) string.")
     kls = keylists(d, indexes=indexes)
     kps = [separator.join([f"{key}" for key in kl]) for kl in kls]