Fixes related to Dask

README.md

@@ -157,6 +157,11 @@ Use the `--ci` flag to run only the primary and special cases tests. You can
 ignore the other test cases as they are redundant for the purposes of checking
 compliance.
 
+#### Data-dependent shapes
+
+Use the `--disable-data-dependent-shapes` flag to skip testing functions which have
+[data-dependent shapes](https://data-apis.org/array-api/latest/design_topics/data_dependent_output_shapes.html).
+
 #### Extensions
 
 By default, tests for the optional Array API extensions such as
@@ -200,16 +205,10 @@ instead of having a seperate `skips.txt` file, e.g.:
         # Skip test cases with known issues
         cat << EOF >> skips.txt
 
-        # Skip specific test case, e.g. when argsort() does not respect relative order
-        # https://github.com/numpy/numpy/issues/20778
+        # Comments can still work here
         array_api_tests/test_sorting_functions.py::test_argsort
-
-        # Skip specific test case parameter, e.g. you forgot to implement in-place adds
         array_api_tests/test_add[__iadd__(x1, x2)]
         array_api_tests/test_add[__iadd__(x, s)]
-
-        # Skip module, e.g. when your set functions treat NaNs as non-distinct
-        # https://github.com/numpy/numpy/issues/20326
         array_api_tests/test_set_functions.py
 
         EOF

array_api_tests/meta/test_pytest_helpers.py

@@ -1,7 +1,7 @@
 from pytest import raises
 
-from .. import pytest_helpers as ph
 from .. import _array_module as xp
+from .. import pytest_helpers as ph
 
 
 def test_assert_dtype():
@@ -11,3 +11,12 @@ def test_assert_dtype():
     ph.assert_dtype("bool_func", [xp.uint8, xp.int8], xp.bool, xp.bool)
     ph.assert_dtype("single_promoted_func", [xp.uint8], xp.uint8)
     ph.assert_dtype("single_bool_func", [xp.uint8], xp.bool, xp.bool)
+
+
+def test_assert_array():
+    ph.assert_array("int zeros", xp.asarray(0), xp.asarray(0))
+    ph.assert_array("pos zeros", xp.asarray(0.0), xp.asarray(0.0))
+    with raises(AssertionError):
+        ph.assert_array("mixed sign zeros", xp.asarray(0.0), xp.asarray(-0.0))
+    with raises(AssertionError):
+        ph.assert_array("mixed sign zeros", xp.asarray(-0.0), xp.asarray(0.0))

array_api_tests/pytest_helpers.py

@@ -14,6 +14,8 @@
     "doesnt_raise",
     "nargs",
     "fmt_kw",
+    "is_pos_zero",
+    "is_neg_zero",
     "assert_dtype",
     "assert_kw_dtype",
     "assert_default_float",
@@ -22,6 +24,7 @@
     "assert_shape",
     "assert_result_shape",
     "assert_keepdimable_shape",
+    "assert_0d_equals",
     "assert_fill",
     "assert_array",
 ]
@@ -69,6 +72,14 @@ def fmt_kw(kw: Dict[str, Any]) -> str:
     return ", ".join(f"{k}={v}" for k, v in kw.items())
 
 
+def is_pos_zero(n: float) -> bool:
+    return n == 0 and math.copysign(1, n) == 1
+
+
+def is_neg_zero(n: float) -> bool:
+    return n == 0 and math.copysign(1, n) == -1
+
+
 def assert_dtype(
     func_name: str,
     in_dtype: Union[DataType, Sequence[DataType]],
@@ -232,15 +243,28 @@ def assert_fill(
 def assert_array(func_name: str, out: Array, expected: Array, /, **kw):
     assert_dtype(func_name, out.dtype, expected.dtype)
     assert_shape(func_name, out.shape, expected.shape, **kw)
-    msg = f"out not as expected [{func_name}({fmt_kw(kw)})]\n{out=}\n{expected=}"
+    f_func = f"[{func_name}({fmt_kw(kw)})]"
     if dh.is_float_dtype(out.dtype):
-        neg_zeros = expected == -0.0
-        assert xp.all((out == -0.0) == neg_zeros), msg
-        pos_zeros = expected == +0.0
-        assert xp.all((out == +0.0) == pos_zeros), msg
-        nans = xp.isnan(expected)
-        assert xp.all(xp.isnan(out) == nans), msg
-        mask = ~(neg_zeros | pos_zeros | nans)
-        assert xp.all(out[mask] == expected[mask]), msg
+        for idx in sh.ndindex(out.shape):
+            at_out = out[idx]
+            at_expected = expected[idx]
+            msg = (
+                f"{sh.fmt_idx('out', idx)}={at_out}, should be {at_expected} "
+                f"{f_func}"
+            )
+            if xp.isnan(at_expected):
+                assert xp.isnan(at_out), msg
+            elif at_expected == 0.0 or at_expected == -0.0:
+                scalar_at_expected = float(at_expected)
+                scalar_at_out = float(at_out)
+                if is_pos_zero(scalar_at_expected):
+                    assert is_pos_zero(scalar_at_out), msg
+                else:
+                    assert is_neg_zero(scalar_at_expected)  # sanity check
+                    assert is_neg_zero(scalar_at_out), msg
+            else:
+                assert at_out == at_expected, msg
     else:
-        assert xp.all(out == expected), msg
+        assert xp.all(out == expected), (
+            f"out not as expected {f_func}\n" f"{out=}\n{expected=}"
+        )

array_api_tests/test_creation_functions.py

@@ -280,7 +280,7 @@ def test_asarray_arrays(x, data):
         if copy:
             assert not xp.all(
                 out == x
-            ), "xp.all(out == x)=True, but should be False after x was mutated\n{out=}"
+            ), f"xp.all(out == x)=True, but should be False after x was mutated\n{out=}"
         elif copy is False:
             pass  # TODO
 

array_api_tests/test_operators_and_elementwise_functions.py

@@ -123,7 +123,10 @@ def default_filter(s: Scalar) -> bool:
 
     Used by default as these values are typically special-cased.
     """
-    return math.isfinite(s) and s is not -0.0 and s is not +0.0
+    if isinstance(s, int):  # note bools are ints
+        return True
+    else:
+        return math.isfinite(s) and s != 0
 
 
 T = TypeVar("T")
@@ -538,7 +541,7 @@ def test_abs(ctx, data):
         abs,  # type: ignore
         expr_template="abs({})={}",
         filter_=lambda s: (
-            s == float("infinity") or (math.isfinite(s) and s is not -0.0)
+            s == float("infinity") or (math.isfinite(s) and not ph.is_neg_zero(s))
         ),
     )
 

array_api_tests/test_searching_functions.py

@@ -21,13 +21,10 @@
     data=st.data(),
 )
 def test_argmax(x, data):
-    kw = data.draw(
-        hh.kwargs(
-            axis=st.none() | st.integers(-x.ndim, max(x.ndim - 1, 0)),
-            keepdims=st.booleans(),
-        ),
-        label="kw",
-    )
+    axis_strat = st.none()
+    if x.ndim > 0:
+        axis_strat |= st.integers(-x.ndim, max(x.ndim - 1, 0))
+    kw = data.draw(hh.kwargs(axis=axis_strat, keepdims=st.booleans()), label="kw")
 
     out = xp.argmax(x, **kw)
 
@@ -56,13 +53,10 @@ def test_argmax(x, data):
     data=st.data(),
 )
 def test_argmin(x, data):
-    kw = data.draw(
-        hh.kwargs(
-            axis=st.none() | st.integers(-x.ndim, max(x.ndim - 1, 0)),
-            keepdims=st.booleans(),
-        ),
-        label="kw",
-    )
+    axis_strat = st.none()
+    if x.ndim > 0:
+        axis_strat |= st.integers(-x.ndim, max(x.ndim - 1, 0))
+    kw = data.draw(hh.kwargs(axis=axis_strat, keepdims=st.booleans()), label="kw")
 
     out = xp.argmin(x, **kw)
 
@@ -82,7 +76,7 @@ def test_argmin(x, data):
         ph.assert_scalar_equals("argmin", int, out_idx, min_i, expected)
 
 
-# TODO: skip if opted out
+@pytest.mark.data_dependent_shapes
 @given(xps.arrays(dtype=xps.scalar_dtypes(), shape=hh.shapes(min_side=1)))
 def test_nonzero(x):
     out = xp.nonzero(x)

array_api_tests/test_set_functions.py

@@ -12,7 +12,7 @@
 from . import shape_helpers as sh
 from . import xps
 
-pytestmark = pytest.mark.ci
+pytestmark = [pytest.mark.ci, pytest.mark.data_dependent_shapes]
 
 
 @given(xps.arrays(dtype=xps.scalar_dtypes(), shape=hh.shapes(min_side=1)))

conftest.py

@@ -35,6 +35,13 @@ def pytest_addoption(parser):
         default=[],
         help="disable testing for Array API extension(s)",
     )
+    # data-dependent shape
+    parser.addoption(
+        "--disable-data-dependent-shapes",
+        "--disable-dds",
+        action="store_true",
+        help="disable testing functions with output shapes dependent on input",
+    )
     # CI
     parser.addoption(
         "--ci",
@@ -47,6 +54,9 @@ def pytest_configure(config):
     config.addinivalue_line(
         "markers", "xp_extension(ext): tests an Array API extension"
     )
+    config.addinivalue_line(
+        "markers", "data_dependent_shapes: output shapes are dependent on inputs"
+    )
     config.addinivalue_line("markers", "ci: primary test")
     # Hypothesis
     hypothesis_max_examples = config.getoption("--hypothesis-max-examples")
@@ -83,9 +93,15 @@ def xp_has_ext(ext: str) -> bool:
 
 def pytest_collection_modifyitems(config, items):
     disabled_exts = config.getoption("--disable-extension")
+    disabled_dds = config.getoption("--disable-data-dependent-shapes")
     ci = config.getoption("--ci")
     for item in items:
         markers = list(item.iter_markers())
+        # skip if specified in skips.txt
+        for id_ in skip_ids:
+            if item.nodeid.startswith(id_):
+                item.add_marker(mark.skip(reason="skips.txt"))
+                break
         # skip if disabled or non-existent extension
         ext_mark = next((m for m in markers if m.name == "xp_extension"), None)
         if ext_mark is not None:
@@ -96,11 +112,14 @@ def pytest_collection_modifyitems(config, items):
                 )
             elif not xp_has_ext(ext):
                 item.add_marker(mark.skip(reason=f"{ext} not found in array module"))
-        # skip if specified in skips.txt
-        for id_ in skip_ids:
-            if item.nodeid.startswith(id_):
-                item.add_marker(mark.skip(reason="skips.txt"))
-                break
+        # skip if disabled by dds flag
+        if disabled_dds:
+            for m in markers:
+                if m.name == "data_dependent_shapes":
+                    item.add_marker(
+                        mark.skip(reason="disabled via --disable-data-dependent-shapes")
+                    )
+                    break
         # skip if test not appropiate for CI
         if ci:
             ci_mark = next((m for m in markers if m.name == "ci"), None)