fix: Correct scalar validity for null timestamps and empty lists

cloudquery/sdk/scalar/list.py

@@ -42,7 +42,7 @@ def set(self, value: Any):
                 scalar = self._type()
                 scalar.set(item)
                 self._value.append(scalar)
-                self._valid = True
+            self._valid = True
             return
 
         raise ScalarInvalidTypeError(f"Invalid type {type(value)} for List")

cloudquery/sdk/scalar/timestamp.py

@@ -18,6 +18,7 @@ def value(self):
 
     def set(self, value: Any):
         if value is None:
+            self._valid = False
             return
 
         if isinstance(value, Timestamp):

tests/scalar/list.py

@@ -1,3 +1,5 @@
+import pytest
+
 from cloudquery.sdk.scalar import String, Bool, List
 
 
@@ -41,3 +43,23 @@ def test_list_eq_invalid():
     l2.set([String(False)])
 
     assert l1 == l2
+
+
+@pytest.mark.parametrize("empty", [[], ()])
+@pytest.mark.parametrize("previous", [None, ["old value"]])
+def test_empty_list_is_valid_independent_of_previous_value(empty, previous):
+    scalar = List(String)
+    if previous is not None:
+        scalar.set(previous)
+    scalar.set(empty)
+    assert scalar.is_valid
+    assert len(scalar) == 0
+    assert str(scalar) == "[]"
+
+    scalar.set(None)
+    assert not scalar.is_valid
+    assert str(scalar) == "null"
+
+    scalar.set(empty)
+    assert scalar.is_valid
+    assert str(scalar) == "[]"

tests/scalar/timestamp.py

@@ -1,5 +1,5 @@
 import pytest
-from datetime import datetime
+from datetime import datetime, time
 from cloudquery.sdk.scalar import Timestamp
 import pandas as pd
 
@@ -56,3 +56,30 @@ def test_timestamp_set(input_value, expected_scalar):
     b = Timestamp()
     b.set(input_value)
     assert b == expected_scalar, f"{b} and {expected_scalar} are not equal"
+
+
+@pytest.mark.parametrize(
+    "input_value",
+    [
+        "2026-10-21T10:00:00Z",
+        datetime(2026, 10, 21, 10),
+        pd.Timestamp("2026-10-21T10:00:00Z"),
+        time(10, 30),
+    ],
+)
+def test_timestamp_set_none_invalidates_and_can_be_reused(input_value):
+    scalar = Timestamp()
+    assert not scalar.is_valid
+    scalar.set(input_value)
+    assert scalar.is_valid
+
+    scalar.set(None)
+    assert not scalar.is_valid
+    assert str(scalar) == "null"
+
+    scalar.set(None)
+    assert not scalar.is_valid
+
+    scalar.set(input_value)
+    assert scalar.is_valid
+    assert scalar == Timestamp(True, input_value)