Test LedgerLite validation and persistence

Author: snafshar

python_practice/2026-10-15/ledgerlite/test_ledgerlite.py

@@ -0,0 +1,48 @@
+"""Unit tests for LedgerLite; run with python -m unittest.""" 
+
+import json
+import tempfile
+import unittest
+from pathlib import Path
+
+from ledgerlite import add_entry, load_entries, save_entries
+
+
+class LedgerLiteTests(unittest.TestCase):
+    def test_add_entry_trims_text_and_stores_amount(self):
+        entries = []
+        entry = add_entry(entries, 12.5, " lunch ", " food ")
+        self.assertEqual(entry["description"], "lunch")
+        self.assertEqual(entry["category"], "food")
+        self.assertEqual(entry["amount"], 12.5)
+        self.assertEqual(len(entries), 1)
+
+    def test_rejects_non_positive_amount(self):
+        with self.assertRaises(ValueError):
+            add_entry([], 0, "coffee", "food")
+
+    def test_rejects_blank_description(self):
+        with self.assertRaises(ValueError):
+            add_entry([], 2, "   ", "food")
+
+    def test_save_and_load_round_trip(self):
+        with tempfile.TemporaryDirectory() as directory:
+            path = Path(directory) / "nested" / "ledger.json"
+            entries = [add_entry([], 4.25, "bus", "transport")]
+            save_entries(path, entries)
+            self.assertEqual(load_entries(path), entries)
+
+    def test_missing_file_is_empty_ledger(self):
+        with tempfile.TemporaryDirectory() as directory:
+            self.assertEqual(load_entries(Path(directory) / "missing.json"), [])
+
+    def test_invalid_json_reports_error(self):
+        with tempfile.TemporaryDirectory() as directory:
+            path = Path(directory) / "broken.json"
+            path.write_text("{not json", encoding="utf-8")
+            with self.assertRaises(ValueError):
+                load_entries(path)
+
+
+if __name__ == "__main__":
+    unittest.main()