 b/tests/unit/test_lookup_struct.py
+import io
+from pathlib import Path
+from unittest.mock import patch
+import docdeid as dd
+from deduce.lookup_structs import (
+    cache_lookup_structs,
+    load_lookup_structs_from_cache,
+    load_raw_itemset,
+    load_raw_itemsets,
+    validate_lookup_struct_cache,
+)
+DATA_PATH = Path(".").cwd() / "tests" / "data" / "lookup"
+class TestLookupStruct:
+    def test_load_raw_itemset(self):
+        raw_itemset = load_raw_itemset(DATA_PATH / "src" / "lst_test")
+        assert len(raw_itemset) == 5
+        assert "de Vries" in raw_itemset
+        assert "De Vries" in raw_itemset
+        assert "Sijbrand" in raw_itemset
+        assert "Sybrand" in raw_itemset
+        assert "Pieters" in raw_itemset
+        assert "Wolter" not in raw_itemset
+    def test_load_raw_itemset_nested(self):
+        raw_itemset = load_raw_itemset(DATA_PATH / "src" / "lst_test_nested")
+        assert raw_itemset == {"a", "b", "c", "d"}
+    def test_load_raw_itemsets(self):
+        raw_itemsets = load_raw_itemsets(
+            base_path=DATA_PATH, subdirs=["lst_test", "lst_test_nested"]
+        )
+        assert "test" in raw_itemsets
+        assert len(raw_itemsets["test"]) == 5
+        assert "test_nested" in raw_itemsets
+        assert len(raw_itemsets["test_nested"]) == 4
+    def test_validate_lookup_struct_cache_valid(self):
+        cache = {
+            "deduce_version": "2.5.0",
+            "saved_datetime": "2023-12-06 10:19:39.198133",
+            "lookup_structs": "_",
+        }
+        class MockStats:
+            st_mtime = 1000000000  # way in the past
+        with patch("pathlib.Path.glob", return_value=[1, 2, 3]):
+            with patch("os.stat", return_value=MockStats()):
+                assert validate_lookup_struct_cache(
+                    cache=cache, base_path=DATA_PATH, deduce_version="2.5.0"
+                )
+    def test_validate_lookup_struct_cache_file_changes(self):
+        cache = {
+            "deduce_version": "2.5.0",
+            "saved_datetime": "2023-12-06 10:19:39.198133",
+            "lookup_structs": "_",
+        }
+        class MockStats:
+            st_mtime = 2000000000  # way in the future
+        with patch("pathlib.Path.glob", return_value=[1, 2, 3]):
+            with patch("os.stat", return_value=MockStats()):
+                assert not validate_lookup_struct_cache(
+                    cache=cache, base_path=DATA_PATH, deduce_version="2.5.0"
+                )
+    @patch("deduce.lookup_structs.validate_lookup_struct_cache", return_value=True)
+    def test_load_lookup_structs_from_cache(self, _):
+        ds_collection = load_lookup_structs_from_cache(
+            cache_path=DATA_PATH, deduce_version="_"
+        )
+        assert len(ds_collection) == 2
+        assert "test" in ds_collection
+        assert "test_nested" in ds_collection
+    @patch("deduce.lookup_structs.validate_lookup_struct_cache", return_value=True)
+    def test_load_lookup_structs_from_cache_nofile(self, _):
+        ds_collection = load_lookup_structs_from_cache(
+            cache_path=DATA_PATH / "non_existing_dir", deduce_version="_"
+        )
+        assert ds_collection is None
+    @patch("deduce.lookup_structs.validate_lookup_struct_cache", return_value=False)
+    def test_load_lookup_structs_from_cache_invalid(self, _):
+        ds_collection = load_lookup_structs_from_cache(
+            cache_path=DATA_PATH, deduce_version="_"
+        )
+        assert ds_collection is None
+    @patch("builtins.open", return_value=io.BytesIO())
+    @patch("pickle.dump")
+    def test_cache_lookup_structs(self, _, mock_pickle_dump):
+        cache_lookup_structs(
+            lookup_structs=dd.ds.DsCollection(),
+            cache_path=DATA_PATH,
+            deduce_version="2.5.0",
+        )
+        assert mock_pickle_dump.called_once()