Add tests for paginator signature matching (#779)

These tests enforce that decorated methods of the target client
classes satisfy the paginator interfaces for their decorators.

For example, if a method is decorated with the MarkerPaginator, then
it must take a named argument `marker` for the paginator to use.

It's acceptable for the argument to be keyword-only or for it to be
positional-or-keyword. But it's not acceptable for it to be, e.g.,
positional-only.

tests/unit/test_paginator_signature_matching.py

@@ -0,0 +1,81 @@
+"""
+Inspect the signatures of paginated methods and compare them against their
+attached paginator requirements.
+"""
+import inspect
+
+import pytest
+
+import globus_sdk
+from globus_sdk.paging import (
+    HasNextPaginator,
+    LastKeyPaginator,
+    LimitOffsetTotalPaginator,
+    MarkerPaginator,
+    NextTokenPaginator,
+    NullableMarkerPaginator,
+)
+
+_CLIENTS_TO_CHECK = (
+    # alphabetical by service name
+    # Auth
+    globus_sdk.AuthClient,
+    globus_sdk.NativeAppAuthClient,
+    globus_sdk.ConfidentialAppAuthClient,
+    # Flows
+    globus_sdk.FlowsClient,
+    globus_sdk.SpecificFlowClient,
+    # GCS
+    globus_sdk.GCSClient,
+    # Groups
+    globus_sdk.GroupsClient,
+    # Search
+    globus_sdk.SearchClient,
+    # Timers
+    globus_sdk.TimerClient,
+    # Transfer
+    globus_sdk.TransferClient,
+)
+
+_METHODS_TO_CHECK = []
+for cls in _CLIENTS_TO_CHECK:
+    methods = inspect.getmembers(cls, predicate=inspect.isfunction)
+    for name, value in methods:
+        if name.startswith("_"):
+            continue
+        # inherited, non-overloaded methods
+        if name not in cls.__dict__:
+            continue
+        if getattr(value, "_has_paginator", False):
+            _METHODS_TO_CHECK.append(value)
+
+
+@pytest.mark.parametrize("method", _METHODS_TO_CHECK)
+def test_paginated_method_matches_paginator_requirements(method):
+    paginator_class = method._paginator_class
+
+    sig = inspect.signature(method)
+    kwarg_names = {
+        p.name
+        for p in sig.parameters.values()
+        if p.kind in (p.POSITIONAL_OR_KEYWORD, p.KEYWORD_ONLY)
+    }
+
+    if (
+        paginator_class is HasNextPaginator
+        or paginator_class is LimitOffsetTotalPaginator
+    ):
+        expect_params = ("limit", "offset")
+    elif (
+        paginator_class is MarkerPaginator or paginator_class is NullableMarkerPaginator
+    ):
+        expect_params = ("marker",)
+    elif paginator_class is LastKeyPaginator:
+        expect_params = ("last_key",)
+    elif paginator_class is NextTokenPaginator:
+        expect_params = ("next_token",)
+    else:
+        raise NotImplementedError(f"unrecognized paginator class: {paginator_class}")
+
+    for param_name in expect_params:
+        assert param_name in kwarg_names, method.__qualname__