1 files changed, 133 insertions, 0 deletions
diff --git a/test/test_transform_mixin.py b/test/test_transform_mixin.py
new file mode 100644
index 0000000..5efdf37
--- /dev/null
+++ b/test/test_transform_mixin.py
@@ -0,0 +1,133 @@
+"""Tests for TransformMixin."""
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+import pytest
+
+from ansiblelint.rules import TransformMixin
+
+if TYPE_CHECKING:
+    from typing import Any, Dict, List, MutableMapping, MutableSequence, Type, Union
+
+
+DUMMY_MAP: dict[str, Any] = {
+    "foo": "text",
+    "bar": {"some": "text2"},
+    "fruits": ["apple", "orange"],
+    "answer": [{"forty-two": ["life", "universe", "everything"]}],
+}
+DUMMY_LIST: list[dict[str, Any]] = [
+    {"foo": "text"},
+    {"bar": {"some": "text2"}, "fruits": ["apple", "orange"]},
+    {"answer": [{"forty-two": ["life", "universe", "everything"]}]},
+]
+
+
+@pytest.mark.parametrize(
+    ("yaml_path", "data", "expected_error"),
+    (
+        ([0], DUMMY_MAP, KeyError),
+        (["bar", 0], DUMMY_MAP, KeyError),
+        (["fruits", 100], DUMMY_MAP, IndexError),
+        (["answer", 1], DUMMY_MAP, IndexError),
+        (["answer", 0, 42], DUMMY_MAP, KeyError),
+        (["answer", 0, "42"], DUMMY_MAP, KeyError),
+        ([100], DUMMY_LIST, IndexError),
+        ([0, 0], DUMMY_LIST, KeyError),
+        ([0, "wrong key"], DUMMY_LIST, KeyError),
+        ([1, "bar", "wrong key"], DUMMY_LIST, KeyError),
+        ([1, "fruits", "index should be int"], DUMMY_LIST, TypeError),
+        ([1, "fruits", 100], DUMMY_LIST, IndexError),
+    ),
+)
+def test_seek_with_bad_path(
+    yaml_path: list[int | str],
+    data: MutableMapping[str, Any] | MutableSequence[Any] | str,
+    expected_error: type[Exception],
+) -> None:
+    """Verify that TransformMixin.seek() propagates errors."""
+    with pytest.raises(expected_error):
+        TransformMixin.seek(yaml_path, data)
+
+
+@pytest.mark.parametrize(
+    ("yaml_path", "data", "expected"),
+    (
+        ([], DUMMY_MAP, DUMMY_MAP),
+        (["foo"], DUMMY_MAP, DUMMY_MAP["foo"]),
+        (["bar"], DUMMY_MAP, DUMMY_MAP["bar"]),
+        (["bar", "some"], DUMMY_MAP, DUMMY_MAP["bar"]["some"]),
+        (["fruits"], DUMMY_MAP, DUMMY_MAP["fruits"]),
+        (["fruits", 0], DUMMY_MAP, DUMMY_MAP["fruits"][0]),
+        (["fruits", 1], DUMMY_MAP, DUMMY_MAP["fruits"][1]),
+        (["answer"], DUMMY_MAP, DUMMY_MAP["answer"]),
+        (["answer", 0], DUMMY_MAP, DUMMY_MAP["answer"][0]),
+        (["answer", 0, "forty-two"], DUMMY_MAP, DUMMY_MAP["answer"][0]["forty-two"]),
+        (
+            ["answer", 0, "forty-two", 0],
+            DUMMY_MAP,
+            DUMMY_MAP["answer"][0]["forty-two"][0],
+        ),
+        (
+            ["answer", 0, "forty-two", 1],
+            DUMMY_MAP,
+            DUMMY_MAP["answer"][0]["forty-two"][1],
+        ),
+        (
+            ["answer", 0, "forty-two", 2],
+            DUMMY_MAP,
+            DUMMY_MAP["answer"][0]["forty-two"][2],
+        ),
+        ([], DUMMY_LIST, DUMMY_LIST),
+        ([0], DUMMY_LIST, DUMMY_LIST[0]),
+        ([0, "foo"], DUMMY_LIST, DUMMY_LIST[0]["foo"]),
+        ([1], DUMMY_LIST, DUMMY_LIST[1]),
+        ([1, "bar"], DUMMY_LIST, DUMMY_LIST[1]["bar"]),
+        ([1, "bar", "some"], DUMMY_LIST, DUMMY_LIST[1]["bar"]["some"]),
+        ([1, "fruits"], DUMMY_LIST, DUMMY_LIST[1]["fruits"]),
+        ([1, "fruits", 0], DUMMY_LIST, DUMMY_LIST[1]["fruits"][0]),
+        ([1, "fruits", 1], DUMMY_LIST, DUMMY_LIST[1]["fruits"][1]),
+        ([2], DUMMY_LIST, DUMMY_LIST[2]),
+        ([2, "answer"], DUMMY_LIST, DUMMY_LIST[2]["answer"]),
+        ([2, "answer", 0], DUMMY_LIST, DUMMY_LIST[2]["answer"][0]),
+        (
+            [2, "answer", 0, "forty-two"],
+            DUMMY_LIST,
+            DUMMY_LIST[2]["answer"][0]["forty-two"],
+        ),
+        (
+            [2, "answer", 0, "forty-two", 0],
+            DUMMY_LIST,
+            DUMMY_LIST[2]["answer"][0]["forty-two"][0],
+        ),
+        (
+            [2, "answer", 0, "forty-two", 1],
+            DUMMY_LIST,
+            DUMMY_LIST[2]["answer"][0]["forty-two"][1],
+        ),
+        (
+            [2, "answer", 0, "forty-two", 2],
+            DUMMY_LIST,
+            DUMMY_LIST[2]["answer"][0]["forty-two"][2],
+        ),
+        (
+            [],
+            "this is a string that should be returned as is, ignoring path.",
+            "this is a string that should be returned as is, ignoring path.",
+        ),
+        (
+            [2, "answer", 0, "forty-two", 2],
+            "this is a string that should be returned as is, ignoring path.",
+            "this is a string that should be returned as is, ignoring path.",
+        ),
+    ),
+)
+def test_seek(
+    yaml_path: list[int | str],
+    data: MutableMapping[str, Any] | MutableSequence[Any] | str,
+    expected: Any,
+) -> None:
+    """Ensure TransformMixin.seek() retrieves the correct data."""
+    actual = TransformMixin.seek(yaml_path, data)
+    assert actual == expected