test: Add unit tests for Delta and DeltaLocator stream_timestamp property

Author: IvanPartsunev

deltacat/tests/storage/model/test_delta.py

@@ -0,0 +1,105 @@
+"""Unit tests for the Delta model."""
+import pytest
+
+from deltacat.storage.model.delta import Delta, DeltaLocator
+
+
+class TestDeltaLocator:
+    """Tests for DeltaLocator stream_timestamp functionality."""
+
+    def test_stream_timestamp_valid(self):
+        """Test that valid millisecond timestamps are accepted."""
+        locator = DeltaLocator.of(
+            partition_locator=None,
+            stream_position=123,
+            stream_timestamp=1705849200000,  # Valid milliseconds timestamp
+        )
+        assert locator.stream_timestamp == 1705849200000
+        assert locator.stream_position == 123
+
+    def test_stream_timestamp_none(self):
+        """Test that None timestamps are accepted."""
+        locator = DeltaLocator.of(
+            partition_locator=None,
+            stream_position=123,
+            stream_timestamp=None,
+        )
+        assert locator.stream_timestamp is None
+        assert locator.stream_position == 123
+
+    def test_stream_timestamp_invalid_too_small(self):
+        """Test that timestamps that are too small are rejected."""
+        locator = DeltaLocator.of()
+        with pytest.raises(ValueError, match="stream_timestamp must be unix milliseconds"):
+            locator.stream_timestamp = 123  # Invalid - not milliseconds (too small)
+
+    def test_stream_timestamp_invalid_too_large(self):
+        """Test that timestamps that are too large are rejected."""
+        locator = DeltaLocator.of()
+        with pytest.raises(ValueError, match="stream_timestamp must be unix milliseconds"):
+            locator.stream_timestamp = 10_000_000_000_000  # Invalid - too large
+
+    def test_stream_timestamp_boundary_min(self):
+        """Test that the minimum valid timestamp is accepted."""
+        locator = DeltaLocator.of()
+        locator.stream_timestamp = 1_000_000_000_000  # Minimum valid
+        assert locator.stream_timestamp == 1_000_000_000_000
+
+    def test_stream_timestamp_boundary_max(self):
+        """Test that the maximum valid timestamp is accepted."""
+        locator = DeltaLocator.of()
+        locator.stream_timestamp = 9_999_999_999_999  # Maximum valid
+        assert locator.stream_timestamp == 9_999_999_999_999
+
+    def test_stream_timestamp_persisted_as_camel_case(self):
+        """Test that stream_timestamp is stored with camelCase key."""
+        locator = DeltaLocator.of()
+        locator.stream_timestamp = 1705849200000
+        assert "streamTimestamp" in locator
+        assert locator["streamTimestamp"] == 1705849200000
+
+
+class TestDelta:
+    """Tests for Delta stream_timestamp property."""
+
+    def test_stream_timestamp_delegates_to_locator(self):
+        """Test that Delta.stream_timestamp delegates to the locator."""
+        locator = DeltaLocator.of(
+            partition_locator=None,
+            stream_position=123,
+            stream_timestamp=1705849200000,
+        )
+        delta = Delta.of(
+            locator=locator,
+            delta_type=None,
+            meta=None,
+            properties=None,
+            manifest=None,
+        )
+        assert delta.stream_timestamp == 1705849200000
+
+    def test_stream_timestamp_returns_none_when_locator_is_none(self):
+        """Test that Delta.stream_timestamp returns None when locator is None."""
+        delta = Delta.of(
+            locator=None,
+            delta_type=None,
+            meta=None,
+            properties=None,
+            manifest=None,
+        )
+        assert delta.stream_timestamp is None
+
+    def test_stream_timestamp_returns_none_when_timestamp_not_set(self):
+        """Test that Delta.stream_timestamp returns None when not set on locator."""
+        locator = DeltaLocator.of(
+            partition_locator=None,
+            stream_position=123,
+        )
+        delta = Delta.of(
+            locator=locator,
+            delta_type=None,
+            meta=None,
+            properties=None,
+            manifest=None,
+        )
+        assert delta.stream_timestamp is None