Add unit tests for guardrail AST utilities

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

tests/test_guardrail_ast_utils.py

@@ -0,0 +1,28 @@
+import ast
+
+from tests.guardrail_ast_utils import (
+    collect_attribute_call_lines,
+    collect_list_keys_call_lines,
+    collect_name_call_lines,
+)
+
+
+SAMPLE_MODULE = ast.parse(
+    """
+values = list(mapping.keys())
+result = helper()
+other = obj.method()
+"""
+)
+
+
+def test_collect_name_call_lines_returns_named_calls():
+    assert collect_name_call_lines(SAMPLE_MODULE, "helper") == [3]
+
+
+def test_collect_attribute_call_lines_returns_attribute_calls():
+    assert collect_attribute_call_lines(SAMPLE_MODULE, "method") == [4]
+
+
+def test_collect_list_keys_call_lines_returns_list_key_calls():
+    assert collect_list_keys_call_lines(SAMPLE_MODULE) == [2]