langgraph checkpoint: new library for checkpoint interfaces (#1163)

---------

Co-authored-by: Nuno Campos <nuno@langchain.dev>

libs/checkpoint/tests/test_sqlite.py

@@ -0,0 +1,125 @@
+import pytest
+from langchain_core.runnables import RunnableConfig
+
+from langgraph.checkpoint.base import (
+    Checkpoint,
+    CheckpointMetadata,
+    create_checkpoint,
+    empty_checkpoint,
+)
+from langgraph.checkpoint.sqlite import SqliteSaver
+from langgraph.checkpoint.sqlite.utils import _metadata_predicate, search_where
+
+
+class TestSqliteSaver:
+    @pytest.fixture(autouse=True)
+    def setup(self):
+        self.sqlite_saver = SqliteSaver.from_conn_string(":memory:")
+
+        # objects for test setup
+        self.config_1: RunnableConfig = {
+            "configurable": {"thread_id": "thread-1", "thread_ts": "1"}
+        }
+        self.config_2: RunnableConfig = {
+            "configurable": {"thread_id": "thread-2", "thread_ts": "2"}
+        }
+
+        self.chkpnt_1: Checkpoint = empty_checkpoint()
+        self.chkpnt_2: Checkpoint = create_checkpoint(self.chkpnt_1, {}, 1)
+
+        self.metadata_1: CheckpointMetadata = {
+            "source": "input",
+            "step": 2,
+            "writes": {},
+            "score": 1,
+        }
+        self.metadata_2: CheckpointMetadata = {
+            "source": "loop",
+            "step": 1,
+            "writes": {"foo": "bar"},
+            "score": None,
+        }
+        self.metadata_3: CheckpointMetadata = {}
+
+    def test_search(self):
+        # set up test
+        # save checkpoints
+        self.sqlite_saver.put(self.config_1, self.chkpnt_1, self.metadata_1)
+        self.sqlite_saver.put(self.config_2, self.chkpnt_2, self.metadata_2)
+
+        # call method / assertions
+        query_1: CheckpointMetadata = {"source": "input"}  # search by 1 key
+        query_2: CheckpointMetadata = {
+            "step": 1,
+            "writes": {"foo": "bar"},
+        }  # search by multiple keys
+        query_3: CheckpointMetadata = {}  # search by no keys, return all checkpoints
+        query_4: CheckpointMetadata = {"source": "update", "step": 1}  # no match
+
+        search_results_1 = list(self.sqlite_saver.list(None, filter=query_1))
+        assert len(search_results_1) == 1
+        assert search_results_1[0].metadata == self.metadata_1
+
+        search_results_2 = list(self.sqlite_saver.list(None, filter=query_2))
+        assert len(search_results_2) == 1
+        assert search_results_2[0].metadata == self.metadata_2
+
+        search_results_3 = list(self.sqlite_saver.list(None, filter=query_3))
+        assert len(search_results_3) == 2
+
+        search_results_4 = list(self.sqlite_saver.list(None, filter=query_4))
+        assert len(search_results_4) == 0
+
+        # TODO: test before and limit params
+
+    def test_search_where(self):
+        # call method / assertions
+        expected_predicate_1 = "WHERE json_extract(CAST(metadata AS TEXT), '$.source') = ? AND json_extract(CAST(metadata AS TEXT), '$.step') = ? AND json_extract(CAST(metadata AS TEXT), '$.writes') = ? AND json_extract(CAST(metadata AS TEXT), '$.score') = ? AND thread_ts < ?"
+        expected_param_values_1 = ["input", 2, "{}", 1, "1"]
+        assert search_where(None, self.metadata_1, self.config_1) == (
+            expected_predicate_1,
+            expected_param_values_1,
+        )
+
+    def test_metadata_predicate(self):
+        # call method / assertions
+        expected_predicate_1 = [
+            "json_extract(CAST(metadata AS TEXT), '$.source') = ?",
+            "json_extract(CAST(metadata AS TEXT), '$.step') = ?",
+            "json_extract(CAST(metadata AS TEXT), '$.writes') = ?",
+            "json_extract(CAST(metadata AS TEXT), '$.score') = ?",
+        ]
+        expected_predicate_2 = [
+            "json_extract(CAST(metadata AS TEXT), '$.source') = ?",
+            "json_extract(CAST(metadata AS TEXT), '$.step') = ?",
+            "json_extract(CAST(metadata AS TEXT), '$.writes') = ?",
+            "json_extract(CAST(metadata AS TEXT), '$.score') IS ?",
+        ]
+        expected_predicate_3 = []
+
+        expected_param_values_1 = ["input", 2, "{}", 1]
+        expected_param_values_2 = ["loop", 1, '{"foo":"bar"}', None]
+        expected_param_values_3 = []
+
+        assert _metadata_predicate(self.metadata_1) == (
+            expected_predicate_1,
+            expected_param_values_1,
+        )
+        assert _metadata_predicate(self.metadata_2) == (
+            expected_predicate_2,
+            expected_param_values_2,
+        )
+        assert _metadata_predicate(self.metadata_3) == (
+            expected_predicate_3,
+            expected_param_values_3,
+        )
+
+    async def test_informative_async_errors(self):
+        # call method / assertions
+        with pytest.raises(NotImplementedError, match="AsyncSqliteSaver"):
+            await self.sqlite_saver.aget(self.config_1)
+        with pytest.raises(NotImplementedError, match="AsyncSqliteSaver"):
+            await self.sqlite_saver.aget_tuple(self.config_1)
+        with pytest.raises(NotImplementedError, match="AsyncSqliteSaver"):
+            async for _ in self.sqlite_saver.alist(self.config_1):
+                pass