Fix DuplicateChildError on indented ! section separators in IOS-XR (#231)

CHANGELOG.md

@@ -14,6 +14,13 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Performance benchmarks for parsing, remediation, and iteration (#202).
   Skipped by default; run with `poetry run pytest -m benchmark -v -s`.
 
+### Fixed
+
+- `DuplicateChildError` raised when parsing IOS-XR configs with indented `!` section
+  separators (e.g., ` !`, `  !`). The `per_line_sub` regex was changed from `^!\s*$`
+  to `^\s*!\s*$` so bare `!` lines at any indentation level are stripped, restoring
+  v3.4.2 behavior (#231).
+
 ---
 
 ## [3.5.0] - 2026-03-19

hier_config/platforms/cisco_xr/driver.py

@@ -179,7 +179,7 @@ def _instantiate_rules() -> HConfigDriverRules:
                 PerLineSubRule(search="^end-group$", replace=" end-group"),
                 PerLineSubRule(search="^end$", replace=""),
                 PerLineSubRule(search="^\\s*#.*", replace=""),
-                PerLineSubRule(search="^!\\s*$", replace=""),
+                PerLineSubRule(search="^\\s*!\\s*$", replace=""),
             ],
             post_load_callbacks=[_fixup_xr_comments],
             idempotent_commands=[

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "hier-config"
-version = "3.5.0"
+version = "3.5.1"
 description = "A network configuration query and comparison library, used to build remediation configurations."
 packages = [
     { include="hier_config", from="."},

tests/test_driver_cisco_xr.py

@@ -639,3 +639,135 @@ def test_sectional_exit_text_multiple_sections() -> None:
         "  192.0.2.0/24",
         "end-set",
     )
+
+
+def test_indented_bang_section_separators_no_duplicate_child_error() -> None:
+    """Test that indented ! section separators don't raise DuplicateChildError (issue #231)."""
+    platform = Platform.CISCO_XR
+    config_text = """\
+telemetry model-driven
+ destination-group DEST-GROUP-1
+  address-family ipv4 10.0.0.1 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+  !
+ !
+ destination-group DEST-GROUP-2
+  address-family ipv4 10.0.0.2 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+  !
+ !
+ sensor-group SENSOR-1
+  sensor-path openconfig-platform:components/component/cpu
+  sensor-path openconfig-platform:components/component/memory
+ !
+ sensor-group SENSOR-2
+  sensor-path openconfig-interfaces:interfaces/interface/state/counters
+ !
+!
+"""
+    hconfig = get_hconfig(platform, config_text)
+    telemetry = hconfig.get_child(equals="telemetry model-driven")
+    assert telemetry is not None
+    child_texts = [child.text for child in telemetry.children]
+    assert "destination-group DEST-GROUP-1" in child_texts
+    assert "destination-group DEST-GROUP-2" in child_texts
+    assert "sensor-group SENSOR-1" in child_texts
+    assert "sensor-group SENSOR-2" in child_texts
+
+
+def test_running_with_bang_separators_intended_without_no_remediation() -> None:
+    """Running config with indented ! separators and intended without produces no remediation."""
+    platform = Platform.CISCO_XR
+    running = get_hconfig(
+        platform,
+        """\
+telemetry model-driven
+ destination-group DEST-GROUP-1
+  address-family ipv4 10.0.0.1 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+  !
+ !
+ destination-group DEST-GROUP-2
+  address-family ipv4 10.0.0.2 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+  !
+ !
+""",
+    )
+    intended = get_hconfig(
+        platform,
+        """\
+telemetry model-driven
+ destination-group DEST-GROUP-1
+  address-family ipv4 10.0.0.1 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+ destination-group DEST-GROUP-2
+  address-family ipv4 10.0.0.2 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+""",
+    )
+    assert running.config_to_get_to(intended).dump_simple() == ()
+
+
+def test_intended_with_bang_comments_running_without_no_remediation() -> None:
+    """Intended config with ! comment lines and running without produces no remediation."""
+    platform = Platform.CISCO_XR
+    running = get_hconfig(
+        platform,
+        """\
+telemetry model-driven
+ destination-group DEST-GROUP-1
+  address-family ipv4 10.0.0.1 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+ destination-group DEST-GROUP-2
+  address-family ipv4 10.0.0.2 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+""",
+    )
+    intended = get_hconfig(
+        platform,
+        """\
+telemetry model-driven
+ ! This is a test comment
+ ! This is a second test comment
+ destination-group DEST-GROUP-1
+  address-family ipv4 10.0.0.1 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+ destination-group DEST-GROUP-2
+  address-family ipv4 10.0.0.2 port 57000
+   encoding self-describing-gpb
+   protocol tcp
+""",
+    )
+    assert running.config_to_get_to(intended).dump_simple() == ()
+
+
+def test_differing_bang_comment_text_produces_no_remediation() -> None:
+    """Differing ! comment text between running and intended produces no remediation."""
+    platform = Platform.CISCO_XR
+    running = get_hconfig(
+        platform,
+        """\
+router isis backbone
+ ! original comment
+ net 49.0001.1921.2022.0222.00
+""",
+    )
+    intended = get_hconfig(
+        platform,
+        """\
+router isis backbone
+ ! completely different comment
+ net 49.0001.1921.2022.0222.00
+""",
+    )
+    assert running.config_to_get_to(intended).dump_simple() == ()

tests/test_xr_comments.py

@@ -123,3 +123,22 @@ def test_xr_comment_with_leading_bang_preserved() -> None:
     net_child = router_isis.get_child(startswith="net ")
     assert net_child is not None
     assert "!important note about ISIS" in net_child.comments
+
+
+def test_xr_trailing_comment_with_no_following_sibling_is_dropped() -> None:
+    """A trailing ! comment at the end of a section with no following sibling is silently dropped."""
+    config = get_hconfig(
+        Platform.CISCO_XR,
+        """\
+router isis backbone
+ net 49.0001.1921.2022.0222.00
+ ! trailing comment with no following sibling
+""",
+    )
+    router_isis = config.get_child(equals="router isis backbone")
+    assert router_isis is not None
+    net_child = router_isis.get_child(startswith="net ")
+    assert net_child is not None
+    assert len(net_child.comments) == 0
+    for child in router_isis.all_children():
+        assert not child.text.startswith("!")