test: add edge case coverage for factories and equality (#18)

Add tests for:
- Duplicate keys behavior in from_records (last-wins)
- Empty file handling with key parameter in from_file
- Custom default value in Table.get()
- Equality with different auto_reload after external changes
- Transaction equality with different write sequences

Author: tbhb

tests/unit/test_factories.py

@@ -60,6 +60,19 @@ def test_compound_key(self, tmp_path: "Path") -> None:
         assert table.count() == 2
         assert table.get(("acme", 1)) == {"org": "acme", "id": 1, "name": "alice"}
 
+    def test_duplicate_keys_last_wins(self, tmp_path: "Path") -> None:
+        records = [
+            {"id": "alice", "role": "admin"},
+            {"id": "alice", "role": "user"},  # Duplicate key, different value
+        ]
+        table = Table.from_records(
+            tmp_path / "test.jsonlt",
+            records,
+            key="id",
+        )
+        assert table.count() == 1
+        assert table.get("alice") == {"id": "alice", "role": "user"}
+
     def test_file_has_header(self, tmp_path: "Path") -> None:
         table = Table.from_records(
             tmp_path / "test.jsonlt",
@@ -296,6 +309,13 @@ def test_max_file_size_exceeded(self, tmp_path: "Path") -> None:
         with pytest.raises(LimitError, match="file size"):
             _ = Table.from_file(path, max_file_size=10)  # Very small limit
 
+    def test_empty_file_with_key(self, tmp_path: "Path") -> None:
+        path = tmp_path / "test.jsonlt"
+        _ = path.write_bytes(b"")  # 0-byte file
+
+        table = Table.from_file(path, key="id")
+        assert table.count() == 0
+
 
 class TestFactoryIntegration:
     def test_roundtrip_from_records_to_from_file(self, tmp_path: "Path") -> None:

tests/unit/test_table.py

@@ -1283,6 +1283,14 @@ def test_getitem_missing_key_raises_keyerror(
 
         assert exc_info.value.args[0] == "nonexistent"
 
+    def test_get_with_custom_default(self, make_table: "Callable[..., Table]") -> None:
+        table = make_table()
+        default: JSONObject = {"id": "default", "role": "none"}
+
+        result = table.get("nonexistent", default)
+
+        assert result == default
+
     def test_setitem_with_matching_key(
         self, make_table: "Callable[..., Table]"
     ) -> None:
@@ -1536,3 +1544,18 @@ def test_table_is_not_hashable(self, make_table: "Callable[..., Table]") -> None
 
         with pytest.raises(TypeError, match="unhashable type"):
             _ = hash(table)
+
+    def test_eq_with_different_auto_reload_after_external_change(
+        self, tmp_path: "Path"
+    ) -> None:
+        table_path = tmp_path / "test.jsonlt"
+        _ = table_path.write_text('{"id": "alice", "v": 1}\n')
+
+        table1 = Table(table_path, key="id", auto_reload=True)
+        table2 = Table(table_path, key="id", auto_reload=False)
+
+        # Wait a bit to ensure mtime changes
+        time.sleep(0.01)
+        _ = table_path.write_text('{"id": "alice", "v": 2}\n')
+
+        assert table1 != table2

tests/unit/test_transaction.py

@@ -1425,6 +1425,34 @@ def test_finalized_vs_active_not_equal(self, tmp_path: "Path") -> None:
         finally:
             tx2.abort()
 
+    def test_eq_same_table_different_writes(self, tmp_path: "Path") -> None:
+        """Two transactions from same table with different writes are unequal.
+
+        Verifies that sequential transactions from the same table with different
+        write sequences have different snapshots and compare as unequal.
+        """
+        path = tmp_path / "test.jsonlt"
+        _ = path.write_text('{"id": "alice", "v": 1}\n')
+
+        table = Table(path, key="id")
+
+        # First transaction: add bob
+        tx1 = table.transaction()
+        tx1.put({"id": "bob", "v": 2})
+        tx1.commit()
+
+        # Second transaction: add carol (different write)
+        tx2 = table.transaction()
+        tx2.put({"id": "carol", "v": 3})
+
+        try:
+            # tx1 is committed (has alice+bob in snapshot)
+            # tx2 is active (has alice+bob+carol in snapshot)
+            # They differ in both finalized status and snapshot content
+            assert tx1 != tx2
+        finally:
+            tx2.abort()
+
     def test_transaction_is_not_hashable(
         self, make_table: "Callable[..., Table]"
     ) -> None: