pytest-lsp: Passthrough requested fixtures to user fixture func

docs/pytest-lsp/guide/fixtures.rst

@@ -13,3 +13,14 @@ This can be used to run the same set of tests while pretending to be a different
    :language: python
    :start-at: @pytest_lsp.fixture
    :end-at: await lsp_client.shutdown_session()
+
+
+Requesting Other Fixtures
+-------------------------
+
+As you would expect, it's possible to request other fixtures to help set up your client.
+
+.. literalinclude:: ../../../lib/pytest-lsp/tests/examples/fixture-passthrough/t_server.py
+   :language: python
+   :start-at: @pytest.fixture
+   :end-at: await lsp_client.shutdown_session()

lib/pytest-lsp/changes/71.enhancement.rst

@@ -0,0 +1 @@
+Fixtures created with the `@pytest_lsp.fixture` decorator can now request additional pytest fixtures

lib/pytest-lsp/pytest_lsp/plugin.py

@@ -121,17 +121,46 @@ async def anext(it):
         return await it.__anext__()
 
 
-def get_fixture_arguments(fn: Callable, client: LanguageClient, request) -> dict:
-    """Return the arguments to pass to the user's fixture function"""
+def get_fixture_arguments(
+    fn: Callable,
+    client: LanguageClient,
+    request: pytest.FixtureRequest,
+) -> dict:
+    """Return the arguments to pass to the user's fixture function.
+
+    Parameters
+    ----------
+    fn
+       The user's fixture function
+
+    client
+       The language client instance to inject
+
+    request
+       pytest's request fixture
+
+    Returns
+    -------
+    dict
+       The set of arguments to pass to the user's fixture function
+    """
     kwargs = {}
+    required_parameters = set(inspect.signature(fn).parameters.keys())
 
-    parameters = inspect.signature(fn).parameters
-    if "request" in parameters:
+    # Inject the 'request' fixture if requested
+    if "request" in required_parameters:
         kwargs["request"] = request
+        required_parameters.remove("request")
 
+    # Inject the language client
     for name, cls in typing.get_type_hints(fn).items():
         if issubclass(cls, LanguageClient):
             kwargs[name] = client
+            required_parameters.remove(name)
+
+    # Assume all remaining parameters are pytest fixtures
+    for name in required_parameters:
+        kwargs[name] = request.getfixturevalue(name)
 
     return kwargs
 

lib/pytest-lsp/tests/examples/fixture-passthrough/server.py

@@ -0,0 +1,18 @@
+from lsprotocol.types import TEXT_DOCUMENT_COMPLETION
+from lsprotocol.types import CompletionItem
+from lsprotocol.types import CompletionParams
+from pygls.server import LanguageServer
+
+server = LanguageServer("hello-world", "v1")
+
+
+@server.feature(TEXT_DOCUMENT_COMPLETION)
+def completion(ls: LanguageServer, params: CompletionParams):
+    return [
+        CompletionItem(label="hello"),
+        CompletionItem(label="world"),
+    ]
+
+
+if __name__ == "__main__":
+    server.start_io()

lib/pytest-lsp/tests/examples/fixture-passthrough/t_server.py

@@ -0,0 +1,52 @@
+import sys
+
+import pytest
+from lsprotocol.types import CompletionList
+from lsprotocol.types import CompletionParams
+from lsprotocol.types import InitializeParams
+from lsprotocol.types import Position
+from lsprotocol.types import TextDocumentIdentifier
+
+import pytest_lsp
+from pytest_lsp import ClientServerConfig
+from pytest_lsp import LanguageClient
+from pytest_lsp import client_capabilities
+
+
+@pytest.fixture(scope="module")
+def client_name():
+    return "neovim"
+
+
+@pytest_lsp.fixture(
+    config=ClientServerConfig(server_command=[sys.executable, "server.py"]),
+)
+async def client(client_name: str, lsp_client: LanguageClient):
+    # Setup
+    params = InitializeParams(capabilities=client_capabilities(client_name))
+    await lsp_client.initialize_session(params)
+
+    yield
+
+    # Teardown
+    await lsp_client.shutdown_session()
+
+
+async def test_completions(client: LanguageClient):
+    """Ensure that the server implements completions correctly."""
+
+    results = await client.text_document_completion_async(
+        params=CompletionParams(
+            position=Position(line=1, character=0),
+            text_document=TextDocumentIdentifier(uri="file:///path/to/file.txt"),
+        )
+    )
+    assert results is not None
+
+    if isinstance(results, CompletionList):
+        items = results.items
+    else:
+        items = results
+
+    labels = [item.label for item in items]
+    assert labels == ["hello", "world"]

lib/pytest-lsp/tests/test_examples.py

@@ -27,6 +27,7 @@ def setup_test(pytester: pytest.Pytester, example_name: str):
     [
         ("diagnostics", dict(passed=1)),
         ("getting-started", dict(passed=1)),
+        ("fixture-passthrough", dict(passed=1)),
         ("parameterised-clients", dict(passed=2)),
         ("window-log-message", dict(passed=1)),
         ("window-show-document", dict(passed=1)),