fix(stattests): silence scipy>=1.17 anderson_ksamp midrank deprecation (#1534)

src/evidently/legacy/calculations/stattests/anderson_darling_stattest.py

@@ -26,20 +26,37 @@
 from typing import Tuple
 
 import pandas as pd
+import scipy
 from scipy.stats import anderson_ksamp
 
 from evidently.legacy.calculations.stattests.registry import StatTest
 from evidently.legacy.calculations.stattests.registry import register_stattest
 from evidently.legacy.core import ColumnType
 
+# scipy>=1.17 deprecates the `midrank` keyword in favour of `variant=`. When
+# `variant` is supplied the return object is no longer a 3-tuple and exposes
+# `pvalue` instead. Use the new API on scipy>=1.17 to silence the
+# DeprecationWarning reported in issue #1534, and fall back to the legacy
+# tuple shape on older scipy. The minimum supported scipy is 1.10 per
+# pyproject.toml, so the fallback path is required.
+_SCIPY_VERSION: Tuple[int, ...] = tuple(int(p) for p in scipy.__version__.split(".")[:2] if p.isdigit())
+_USE_VARIANT_KWARG = _SCIPY_VERSION >= (1, 17)
+
 
 def _anderson_darling(
     reference_data: pd.Series,
     current_data: pd.Series,
     feature_type: ColumnType,
     threshold: float,
 ) -> Tuple[float, bool]:
-    p_value = anderson_ksamp([reference_data.values, current_data.values])[2]
+    samples = [reference_data.values, current_data.values]
+    if _USE_VARIANT_KWARG:
+        # New scipy API: returns a result object with a `.pvalue` attribute.
+        result = anderson_ksamp(samples, variant="midrank")
+        p_value = result.pvalue
+    else:
+        # Legacy 3-tuple: (statistic, critical_values, significance_level).
+        p_value = anderson_ksamp(samples)[2]
     return p_value, p_value < threshold
 
 

tests/stattests/test_stattests.py

@@ -110,6 +110,23 @@ def test_anderson_darling() -> None:
     assert anderson_darling_test.func(reference, current, "num", 0.001) == (approx(0.0635, abs=1e-3), False)
 
 
+def test_anderson_darling_no_scipy_deprecation_warning() -> None:
+    """Regression test for issue #1534: scipy>=1.17 deprecated the implicit
+    `midrank` default of anderson_ksamp. Calling the Evidently stat test
+    must not emit a DeprecationWarning about it."""
+    import warnings
+
+    reference = pd.Series([38.7, 41.5, 43.8, 44.5, 45.5, 46.0, 47.7, 58.0])
+    current = pd.Series([39.2, 39.3, 39.7, 41.4, 41.8, 42.9, 43.3, 45.8])
+    with warnings.catch_warnings(record=True) as caught:
+        warnings.simplefilter("always")
+        anderson_darling_test.func(reference, current, "num", 0.001)
+    midrank_warnings = [w for w in caught if "midrank" in str(w.message) or "variant" in str(w.message)]
+    assert not midrank_warnings, (
+        "anderson_ksamp emitted a midrank/variant DeprecationWarning: " f"{[str(w.message) for w in midrank_warnings]}"
+    )
+
+
 def test_g_test() -> None:
     reference = pd.Series(["a", "b", "c"]).repeat([5, 5, 8])
     current = pd.Series(["a", "b", "c"]).repeat([4, 6, 8])