Add new beta StructuredPrompt (#19080)

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libs/core/tests/unit_tests/prompts/test_structured.py

@@ -0,0 +1,78 @@
+from functools import partial
+from inspect import isclass
+from typing import Any, Dict, Type, Union, cast
+
+from langchain_core.load.dump import dumps
+from langchain_core.load.load import loads
+from langchain_core.prompts.structured import StructuredPrompt
+from langchain_core.pydantic_v1 import BaseModel
+from langchain_core.runnables.base import Runnable, RunnableLambda
+from tests.unit_tests.fake.chat_model import FakeListChatModel
+
+
+def _fake_runnable(
+    schema: Union[Dict, Type[BaseModel]], _: Any
+) -> Union[BaseModel, Dict]:
+    if isclass(schema) and issubclass(schema, BaseModel):
+        return schema(name="yo", value=42)
+    else:
+        params = cast(Dict, schema)["parameters"]
+        return {k: 1 for k, v in params.items()}
+
+
+class FakeStructuredChatModel(FakeListChatModel):
+    """Fake ChatModel for testing purposes."""
+
+    def with_structured_output(self, schema: Union[Dict, Type[BaseModel]]) -> Runnable:
+        return RunnableLambda(partial(_fake_runnable, schema))
+
+    @property
+    def _llm_type(self) -> str:
+        return "fake-messages-list-chat-model"
+
+
+def test_structured_prompt_pydantic() -> None:
+    class OutputSchema(BaseModel):
+        name: str
+        value: int
+
+    prompt = StructuredPrompt.from_messages_and_schema(
+        [
+            ("human", "I'm very structured, how about you?"),
+        ],
+        OutputSchema,
+    )
+
+    model = FakeStructuredChatModel(responses=[])
+
+    chain = prompt | model
+
+    assert chain.invoke({"hello": "there"}) == OutputSchema(name="yo", value=42)
+
+
+def test_structured_prompt_dict() -> None:
+    prompt = StructuredPrompt.from_messages_and_schema(
+        [
+            ("human", "I'm very structured, how about you?"),
+        ],
+        {
+            "name": "yo",
+            "description": "a structured output",
+            "parameters": {
+                "name": {"type": "string"},
+                "value": {"type": "integer"},
+            },
+        },
+    )
+
+    model = FakeStructuredChatModel(responses=[])
+
+    chain = prompt | model
+
+    assert chain.invoke({"hello": "there"}) == {"name": 1, "value": 1}
+
+    assert loads(dumps(prompt)) == prompt
+
+    chain = loads(dumps(prompt)) | model
+
+    assert chain.invoke({"hello": "there"}) == {"name": 1, "value": 1}