ENH: add crude assert_allclose; use value testing in vecdot

Author: ev-br

array_api_tests/pytest_helpers.py

@@ -28,6 +28,7 @@
     "assert_0d_equals",
     "assert_fill",
     "assert_array_elements",
+    "assert_allclose"
 ]
 
 
@@ -599,3 +600,12 @@ def assert_array_elements(
             at_expected = expected[idx]
             msg = msg_template.format(sh.fmt_idx(out_repr, idx), at_out, at_expected)
             assert at_out == at_expected, msg
+
+
+def assert_allclose(actual, desired, *, atol=1e-7, rtol=1e-7, equal_nan=True, msg_extra=""):
+    if equal_nan:
+        # XXX assert same position, mask away
+        pass
+
+    delta = xp.abs(actual - desired)
+    assert xp.all(delta < atol + xp.abs(actual)*rtol), msg_extra

array_api_tests/test_linalg.py

@@ -106,7 +106,11 @@ def _test_stacks(f, *args, res=None, dims=2, true_val=None,
         msg_extra = f'{x_idxes = }, {res_idx = }'
         assert_equal(res_stack, decomp_res_stack, msg_extra)
         if true_val:
-            assert_equal(decomp_res_stack, true_val(*x_stacks, **kw), msg_extra)
+            expected = true_val(*x_stacks, **kw)
+            if decomp_res_stack.dtype in dh.all_float_dtypes:
+                ph.assert_allclose(decomp_res_stack, expected, msg_extra=msg_extra)
+            else:
+                assert_equal(decomp_res_stack, expected, msg_extra)
 
 
 def _test_namedtuple(res, fields, func_name):