FIX Don't raise a deprecation warning for xarray.ufuncs.{angle,iscomplex} (#2615)

* Don't raise a warning for xarray.ufuncs.angle

* Update warning message

Author: rth

xarray/tests/test_ufuncs.py

@@ -172,6 +172,41 @@ def test_xarray_ufuncs_deprecation():
     with pytest.warns(PendingDeprecationWarning, match='xarray.ufuncs'):
         xu.cos(xr.DataArray([0, 1]))
 
+    with pytest.warns(None) as record:
+        xu.angle(xr.DataArray([0, 1]))
+    record = [el.message for el in record
+              if el.category == PendingDeprecationWarning]
+    assert len(record) == 0
+
+
+@requires_np113
+@pytest.mark.filterwarnings('ignore::RuntimeWarning')
+@pytest.mark.parametrize(
+    'name',
+    [name for name in dir(xu)
+        if (not name.startswith('_') and hasattr(np, name)
+            and name not in ['print_function', 'absolute_import', 'division'])]
+)
+def test_numpy_ufuncs(name, request):
+    x = xr.DataArray([1, 1])
+
+    np_func = getattr(np, name)
+    if hasattr(np_func, 'nin') and np_func.nin == 2:
+        args = (x, x)
+    else:
+        args = (x,)
+
+    y = np_func(*args)
+
+    if name in ['angle', 'iscomplex']:
+        # these functions need to be handled with __array_function__ protocol
+        assert isinstance(y, np.ndarray)
+    elif name in ['frexp']:
+        # np.frexp returns a tuple
+        assert not isinstance(y, xr.DataArray)
+    else:
+        assert isinstance(y, xr.DataArray)
+
 
 def test_xarray_ufuncs_pickle():
     a = 1.0

xarray/ufuncs.py

@@ -44,10 +44,12 @@ def __init__(self, name):
         self._name = name
 
     def __call__(self, *args, **kwargs):
-        _warnings.warn(
-            'xarray.ufuncs will be deprecated when xarray no longer supports '
-            'versions of numpy older than v1.13. Instead, use numpy ufuncs '
-            'directly.', PendingDeprecationWarning, stacklevel=2)
+        if self._name not in ['angle', 'iscomplex']:
+            _warnings.warn(
+                'xarray.ufuncs will be deprecated when xarray no longer '
+                'supports versions of numpy older than v1.17. Instead, use '
+                'numpy ufuncs directly.',
+                PendingDeprecationWarning, stacklevel=2)
 
         new_args = args
         f = _dask_or_eager_func(self._name, array_args=slice(len(args)))