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feat(standard-tests): add a property to set the name of the parameter for the number of results to return (#32443)

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Not all retrievers use `k` as param name to set the number of results to
return. Even in LangChain itself. Eg:
bc4251b9e0/libs/core/langchain_core/indexing/in_memory.py (L31)

So it's helpful to be able to change it for a given retriever.
The change also adds hints to disable the tests if the retriever doesn't
support setting the param in the constructor or in the invoke method
(for instance, the `InMemoryDocumentIndex` in the link supports in the
constructor but not in the invoke method).

This change is backward compatible.

---------

Co-authored-by: Mason Daugherty <mason@langchain.dev>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
This commit is contained in:
Christophe Bornet 2025-08-07 17:22:24 +02:00 committed by GitHub
parent e120604774
commit a647073b26
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1 changed files with 70 additions and 18 deletions
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88
libs/standard-tests/langchain_tests/integration_tests/retrievers.py
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@ -24,8 +24,14 @@ class RetrieversIntegrationTests(BaseStandardTests):
@property
@abstractmethod
def retriever_query_example(self) -> str:
"""Returns a str representing the "query" of an example retriever call."""
...
"""Returns a str representing the ``query`` of an example retriever call."""
@property
def num_results_arg_name(self) -> str:
"""Returns the name of the parameter for the number of results returned.
Usually something like ``k`` or ``top_k``."""
return "k"
@pytest.fixture
def retriever(self) -> BaseRetriever:
@ -33,14 +39,34 @@ class RetrieversIntegrationTests(BaseStandardTests):
return self.retriever_constructor(**self.retriever_constructor_params)
def test_k_constructor_param(self) -> None:
"""Test that the retriever constructor accepts a k parameter, representing
"""Test the number of results constructor parameter.
Test that the retriever constructor accepts a parameter representing
the number of documents to return.
By default, the parameter tested is named ``k``, but it can be overridden by
setting the ``num_results_arg_name`` property.
.. note::
If the retriever doesn't support configuring the number of results returned
via the constructor, this test can be skipped using a pytest ``xfail`` on
the test class:
.. code-block:: python
@pytest.mark.xfail(
reason="This retriever doesn't support setting "
"the number of results via the constructor."
)
def test_k_constructor_param(self) -> None:
raise NotImplementedError
.. dropdown:: Troubleshooting
If this test fails, either the retriever constructor does not accept a k
parameter, or the retriever does not return the correct number of documents
(`k`) when it is set.
If this test fails, the retriever constructor does not accept a number
of results parameter, or the retriever does not return the correct number
of documents ( of the one set in ``num_results_arg_name``) when it is
set.
For example, a retriever like
@ -52,29 +78,51 @@ class RetrieversIntegrationTests(BaseStandardTests):
"""
params = {
k: v for k, v in self.retriever_constructor_params.items() if k != "k"
k: v
for k, v in self.retriever_constructor_params.items()
if k != self.num_results_arg_name
}
params_3 = {**params, "k": 3}
params_3 = {**params, self.num_results_arg_name: 3}
retriever_3 = self.retriever_constructor(**params_3)
result_3 = retriever_3.invoke(self.retriever_query_example)
assert len(result_3) == 3
assert all(isinstance(doc, Document) for doc in result_3)
params_1 = {**params, "k": 1}
params_1 = {**params, self.num_results_arg_name: 1}
retriever_1 = self.retriever_constructor(**params_1)
result_1 = retriever_1.invoke(self.retriever_query_example)
assert len(result_1) == 1
assert all(isinstance(doc, Document) for doc in result_1)
def test_invoke_with_k_kwarg(self, retriever: BaseRetriever) -> None:
"""Test that the invoke method accepts a k parameter, representing the number of
documents to return.
"""Test the number of results parameter in ``invoke()``.
Test that the invoke method accepts a parameter representing
the number of documents to return.
By default, the parameter is named ``, but it can be overridden by
setting the ``num_results_arg_name`` property.
.. note::
If the retriever doesn't support configuring the number of results returned
via the invoke method, this test can be skipped using a pytest ``xfail`` on
the test class:
.. code-block:: python
@pytest.mark.xfail(
reason="This retriever doesn't support setting "
"the number of results in the invoke method."
)
def test_invoke_with_k_kwarg(self) -> None:
raise NotImplementedError
.. dropdown:: Troubleshooting
If this test fails, the retriever's invoke method does not accept a k
parameter, or the retriever does not return the correct number of documents
(`k`) when it is set.
If this test fails, the retriever's invoke method does not accept a number
of results parameter, or the retriever does not return the correct number
of documents (``k`` of the one set in ``num_results_arg_name``) when it is
set.
For example, a retriever like
@ -85,11 +133,15 @@ class RetrieversIntegrationTests(BaseStandardTests):
should return 3 documents when invoked with a query.
"""
result_1 = retriever.invoke(self.retriever_query_example, k=1)
result_1 = retriever.invoke(
self.retriever_query_example, None, **{self.num_results_arg_name: 1}
)
assert len(result_1) == 1
assert all(isinstance(doc, Document) for doc in result_1)
result_3 = retriever.invoke(self.retriever_query_example, k=3)
result_3 = retriever.invoke(
self.retriever_query_example, None, **{self.num_results_arg_name: 3}
)
assert len(result_3) == 3
assert all(isinstance(doc, Document) for doc in result_3)
@ -100,8 +152,8 @@ class RetrieversIntegrationTests(BaseStandardTests):
.. dropdown:: Troubleshooting
If this test fails, the retriever's invoke method does not return a list of
`langchain_core.document.Document` objects. Please confirm that your
`_get_relevant_documents` method returns a list of `Document` objects.
``langchain_core.document.Document`` objects. Please confirm that your
``_get_relevant_documents`` method returns a list of ``Document`` objects.
"""
result = retriever.invoke(self.retriever_query_example)