ENH: correct Dask capabilities

Author: crusaderky

array_api_compat/dask/array/_info.py

@@ -68,11 +68,10 @@ def capabilities(self):
         The resulting dictionary has the following keys:
 
         - **"boolean indexing"**: boolean indicating whether an array library
-          supports boolean indexing. Always ``False`` for Dask.
+          supports boolean indexing.
 
         - **"data-dependent shapes"**: boolean indicating whether an array
-          library supports data-dependent output shapes. Always ``False`` for
-          Dask.
+          library supports data-dependent output shapes.
 
         See
         https://data-apis.org/array-api/latest/API_specification/generated/array_api.info.capabilities.html
@@ -99,9 +98,14 @@ def capabilities(self):
 
         """
         return {
-            "boolean indexing": False,
-            "data-dependent shapes": False,
-            # 'max rank' will be part of the 2024.12 standard
+            # Dask support boolean indexing as long as the index has known shape.
+            # The output .shape and .size properties will contain
+            # a non-compliant math.nan instead of None.
+            "boolean indexing": True,
+            # Dask implements unique_values et.al.
+            # The output .shape and .size properties will contain
+            # a non-compliant math.nan instead of None.
+            "data-dependent shapes": True,
             "max dimensions": 64,
         }
 

dask-xfails.txt

@@ -28,12 +28,14 @@ array_api_tests/test_has_names.py::test_has_names[array_method-to_device]
 array_api_tests/test_has_names.py::test_has_names[array_attribute-device]
 array_api_tests/test_has_names.py::test_has_names[array_attribute-mT]
 
-# Fails because shape is NaN since we don't materialize it yet
+# Data-dependent output shape
+# These tests fail as array-api-tests doesn't cope with unknown shapes
+# Also, output shape is (math.nan, ) instead of (None, )
+# Also, da.unique() doesn't accept equals_nan which causes non-compliant
+# output when there are NaNs in the input.
 array_api_tests/test_searching_functions.py::test_nonzero
 array_api_tests/test_set_functions.py::test_unique_all
 array_api_tests/test_set_functions.py::test_unique_counts
-
-# Different error but same cause as above, we're just trying to do ndindex on nan shape
 array_api_tests/test_set_functions.py::test_unique_inverse
 array_api_tests/test_set_functions.py::test_unique_values