ENH: add dtype_helpers.widest_{real,complex}_dtype, use in test_special_cases

Author: ev-br

array_api_tests/dtype_helpers.py

@@ -281,10 +281,23 @@ def __contains__(self, other):
 )
 
 
+# complex128 if available else complex64
+widest_complex_dtype = max(
+    [(dt, dtype_nbits[dt]) for dt in complex_dtypes], key=lambda x: x[1]
+)[0]
+
+
+# float64 if available else float32
+widest_real_dtype = max(
+    [(dt, dtype_nbits[dt]) for dt in real_float_dtypes], key=lambda x: x[1]
+)[0]
+
+
 dtype_components = _make_dtype_mapping_from_names(
     {"complex64": xp.float32, "complex128": xp.float64}
 )
 
+
 def as_real_dtype(dtype):
     """
     Return the corresponding real dtype for a given floating-point dtype.

array_api_tests/test_special_cases.py

@@ -1530,10 +1530,10 @@ def test_unary(func_name, func, case):
 
         # Use the is_complex flag to determine the appropriate dtype
         if case.is_complex:
-            dtype = xp.complex128
+            dtype = dh.widest_complex_dtype
             in_value = case.cond_from_dtype(dtype).example()
         else:
-            dtype = xp.float64
+            dtype = dh.widest_real_dtype
             in_value = case.cond_from_dtype(dtype).example()
 
     # Create array and compute result based on dtype