Store named datetime columns as INTEGER microseconds (datetime_columns)

tests/test_coerce.py

@@ -4,7 +4,7 @@ import uuid
 
 import pytest
 
-from sqlmem._coerce import coerce_params, to_sqlite
+from sqlmem._coerce import coerce_params, to_sqlite, to_sqlite_datetime
 from sqlmem.cache import CacheManager
 
 
@@ -91,6 +91,80 @@ def test_coerce_params_none():
     assert coerce_params(None) is None
 
 
+# --- to_sqlite_datetime (INTEGER µs storage, 1.12.0) ------------------------
+
+
+def test_datetime_to_epoch_micros():
+    # 2026-06-01T10:00:00Z -> microseconds since epoch
+    dt = datetime.datetime(2026, 6, 1, 10, 0, 0, tzinfo=datetime.timezone.utc)
+    expected = int(dt.timestamp() * 1_000_000)
+    assert to_sqlite_datetime(dt) == expected
+
+
+def test_datetime_naive_treated_as_utc():
+    naive = datetime.datetime(2026, 6, 1, 10, 0, 0)
+    aware = naive.replace(tzinfo=datetime.timezone.utc)
+    assert to_sqlite_datetime(naive) == to_sqlite_datetime(aware)
+
+
+def test_datetime_micros_are_exact():
+    dt = datetime.datetime(2026, 6, 5, 14, 54, 24, 823000, tzinfo=datetime.timezone.utc)
+    us = to_sqlite_datetime(dt)
+    # round-trips back to the same instant with no rounding loss
+    back = datetime.datetime(1970, 1, 1, tzinfo=datetime.timezone.utc) + datetime.timedelta(
+        microseconds=us
+    )
+    assert back == dt
+
+
+def test_datetime_none_passes_through():
+    assert to_sqlite_datetime(None) is None
+
+
+def test_datetime_iso_string_parsed():
+    assert to_sqlite_datetime("2026-06-01T10:00:00+00:00") == to_sqlite_datetime(
+        datetime.datetime(2026, 6, 1, 10, 0, 0, tzinfo=datetime.timezone.utc)
+    )
+
+
+def test_datetime_unparseable_is_none():
+    assert to_sqlite_datetime("not a date") is None
+
+
+# --- integration: datetime_columns are stored as INTEGER --------------------
+
+
+def test_datetime_column_stored_as_integer(tmp_path):
+    c = CacheManager(
+        db_path=tmp_path / "cache.db",
+        backup_interval=9999,
+        datetime_columns={"t": ["changed"]},
+    )
+    dt = datetime.datetime(2026, 6, 1, 10, 0, 0, tzinfo=datetime.timezone.utc)
+    c.load_table("t", ["id", "changed"], FakeSource([("1", dt)]))
+
+    # Column declared INTEGER, value stored as µs-since-epoch.
+    coltype = c.connection.execute("PRAGMA table_info(t)").fetchall()
+    types = {row[1]: row[2] for row in coltype}
+    assert types["changed"] == "INTEGER"
+    assert types["id"] == "TEXT"
+    _, out = c.execute_in_memory("SELECT changed FROM t")
+    assert out == [(to_sqlite_datetime(dt),)]
+    c.close()
+
+
+def test_non_datetime_columns_unaffected_by_datetime_columns(tmp_path):
+    c = CacheManager(
+        db_path=tmp_path / "cache.db",
+        backup_interval=9999,
+        datetime_columns={"t": ["changed"]},
+    )
+    c.load_table("t", ["id", "price"], FakeSource([("1", decimal.Decimal("9.99"))]))
+    _, out = c.execute_in_memory("SELECT id, price FROM t")
+    assert out == [("1", "9.99")]  # still TEXT/ISO coercion
+    c.close()
+
+
 # --- integration: values reach the cache through coercion -------------------