core[minor],community[minor]: Upgrade all @root_validator() to @pre_init (#23841)

This PR introduces a @pre_init decorator that's a @root_validator(pre=True) but with all the defaults populated!

libs/community/tests/unit_tests/llms/test_aleph_alpha.py

@@ -9,7 +9,7 @@ from langchain_community.llms.aleph_alpha import AlephAlpha
 
 @pytest.mark.requires("aleph_alpha_client")
 def test_api_key_is_secret_string() -> None:
-    llm = AlephAlpha(aleph_alpha_api_key="secret-api-key")  # type: ignore[call-arg]
+    llm = AlephAlpha(aleph_alpha_api_key="secret-api-key")  # type: ignore
     assert isinstance(llm.aleph_alpha_api_key, SecretStr)
 
 
@@ -17,7 +17,7 @@ def test_api_key_is_secret_string() -> None:
 def test_api_key_masked_when_passed_via_constructor(
     capsys: CaptureFixture,
 ) -> None:
-    llm = AlephAlpha(aleph_alpha_api_key="secret-api-key")  # type: ignore[call-arg]
+    llm = AlephAlpha(aleph_alpha_api_key="secret-api-key")  # type: ignore
     print(llm.aleph_alpha_api_key, end="")  # noqa: T201
     captured = capsys.readouterr()
 

libs/community/tests/unit_tests/llms/test_bedrock.py

@@ -277,9 +277,12 @@ async def async_gen_mock_streaming_response() -> AsyncGenerator[Dict, None]:
 async def test_bedrock_async_streaming_call() -> None:
     # Mock boto3 import
     mock_boto3 = MagicMock()
+    session = MagicMock()
+    session.region_name = "region"
+    mock_boto3.Session.return_value = session
     mock_boto3.Session.return_value.client.return_value = (
-        MagicMock()
-    )  # Mocking the client method of the Session object
+        session  # Mocking the client method of the Session object
+    )
 
     with patch.dict(
         "sys.modules", {"boto3": mock_boto3}

libs/community/tests/unit_tests/load/__snapshots__/test_dump.ambr

@@ -139,7 +139,7 @@
           "model_name": "davinci",
           "temperature": 0.5,
           "max_tokens": 256,
-          "top_p": 1,
+          "top_p": 1.0,
           "n": 1,
           "best_of": 1,
           "openai_api_key": {
@@ -655,7 +655,7 @@
           "model_name": "davinci",
           "temperature": 0.5,
           "max_tokens": 256,
-          "top_p": 1,
+          "top_p": 1.0,
           "n": 1,
           "best_of": 1,
           "openai_api_key": {
@@ -817,7 +817,7 @@
       "model_name": "davinci",
       "temperature": 0.7,
       "max_tokens": 256,
-      "top_p": 1,
+      "top_p": 1.0,
       "n": 1,
       "best_of": 1,
       "openai_api_key": {