Warnings in the test suite

If anyone is looking for any bite-size contributions, the test suite is throwing off many warnings. Most of these indicate that something will break in the future without code changes; thought mostly the code changes are small.

=============================== warnings summary ===============================
/usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/heapdict.py:11
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/heapdict.py:11: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
    class heapdict(collections.MutableMapping):

/usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/pydap/model.py:175
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/pydap/model.py:175: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
    from collections import OrderedDict, Mapping

/usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/pydap/responses/das.py:14
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/pydap/responses/das.py:14: DeprecationWarning: Using or importing the ABCs from 'collections' instead of from 'collections.abc' is deprecated, and in 3.8 it will stop working
    from collections import Iterable

xarray/tests/test_accessor_dt.py::test_cftime_strftime_access[365_day]
  /home/vsts/work/1/s/xarray/tests/test_accessor_dt.py:226: RuntimeWarning: Converting a CFTimeIndex with dates from a non-standard calendar, 'noleap', to a pandas.DatetimeIndex, which uses dates from the standard calendar.  This may lead to subtle errors in operations that depend on the length of time between dates.
    xr.coding.cftimeindex.CFTimeIndex(data.time.values).to_datetimeindex(),

xarray/tests/test_accessor_dt.py::test_cftime_strftime_access[360_day]
  /home/vsts/work/1/s/xarray/tests/test_accessor_dt.py:226: RuntimeWarning: Converting a CFTimeIndex with dates from a non-standard calendar, '360_day', to a pandas.DatetimeIndex, which uses dates from the standard calendar.  This may lead to subtle errors in operations that depend on the length of time between dates.
    xr.coding.cftimeindex.CFTimeIndex(data.time.values).to_datetimeindex(),

xarray/tests/test_accessor_dt.py::test_cftime_strftime_access[julian]
  /home/vsts/work/1/s/xarray/tests/test_accessor_dt.py:226: RuntimeWarning: Converting a CFTimeIndex with dates from a non-standard calendar, 'julian', to a pandas.DatetimeIndex, which uses dates from the standard calendar.  This may lead to subtle errors in operations that depend on the length of time between dates.
    xr.coding.cftimeindex.CFTimeIndex(data.time.values).to_datetimeindex(),

xarray/tests/test_accessor_dt.py::test_cftime_strftime_access[all_leap]
xarray/tests/test_accessor_dt.py::test_cftime_strftime_access[366_day]
  /home/vsts/work/1/s/xarray/tests/test_accessor_dt.py:226: RuntimeWarning: Converting a CFTimeIndex with dates from a non-standard calendar, 'all_leap', to a pandas.DatetimeIndex, which uses dates from the standard calendar.  This may lead to subtle errors in operations that depend on the length of time between dates.
    xr.coding.cftimeindex.CFTimeIndex(data.time.values).to_datetimeindex(),

xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
  /home/vsts/work/1/s/xarray/core/duck_array_ops.py:202: FutureWarning: elementwise comparison failed; returning scalar instead, but in the future will perform elementwise comparison
    flag_array = (arr1 == arr2) | (isnull(arr1) & isnull(arr2))

xarray/tests/test_backends.py::TestZarrDictStore::test_to_zarr_append_compute_false_roundtrip
xarray/tests/test_backends.py::TestZarrDictStore::test_to_zarr_append_compute_false_roundtrip
xarray/tests/test_backends.py::TestZarrDirectoryStore::test_to_zarr_append_compute_false_roundtrip
xarray/tests/test_backends.py::TestZarrDirectoryStore::test_to_zarr_append_compute_false_roundtrip
  /home/vsts/work/1/s/xarray/conventions.py:184: SerializationWarning: variable None has data in the form of a dask array with dtype=object, which means it is being loaded into memory to determine a data type that can be safely stored on disk. To avoid this, coerce this variable to a fixed-size dtype with astype() before saving it.
    SerializationWarning,

xarray/tests/test_backends.py::TestScipyInMemoryData::test_zero_dimensional_variable
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/importlib/_bootstrap.py:219: RuntimeWarning: numpy.ufunc size changed, may indicate binary incompatibility. Expected 192 from C header, got 216 from PyObject
    return f(*args, **kwds)

xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_ict_format
xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_ict_format_write
xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_ict_format_write
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/PseudoNetCDF/icarttfiles/ffi1001.py:80: DeprecationWarning: 'U' mode is deprecated
    f = openf(path, 'rU', encoding = encoding)

xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_ict_format
xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_ict_format_write
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/_pytest/python.py:170: RuntimeWarning: deallocating CachingFileManager(<function pncopen at 0x7f252e49a6a8>, '/home/vsts/work/1/s/xarray/tests/data/example.ict', kwargs={'format': 'ffi1001'}), but file is not already closed. This may indicate a bug.
    result = testfunction(**testargs)

xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_uamiv_format_read
xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_uamiv_format_mfread
xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_uamiv_format_write
xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_uamiv_format_write
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/PseudoNetCDF/camxfiles/uamiv/Memmap.py:141: UserWarning: UnboundLocalError("local variable 'dims' referenced before assignment")
    warn(repr(e))

xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_uamiv_format_mfread
  /home/vsts/work/1/s/xarray/tests/test_backends.py:103: FutureWarning: In xarray version 0.13 the default behaviour of `open_mfdataset`
  will change. To retain the existing behavior, pass
  combine='nested'. To use future default behavior, pass
  combine='by_coords'. See
  http://xarray.pydata.org/en/stable/combining.html#combining-multi
  
    **kwargs

xarray/tests/test_backends.py::TestPseudoNetCDFFormat::test_uamiv_format_mfread
  /home/vsts/work/1/s/xarray/backends/api.py:931: FutureWarning: Also `open_mfdataset` will no longer accept a `concat_dim` argument.
  To get equivalent behaviour from now on please use the new
  `combine_nested` function instead (or the `combine='nested'` option to
  `open_mfdataset`).The datasets supplied do not have global dimension coordinates. In
  future, to continue concatenating without supplying dimension
  coordinates, please use the new `combine_nested` function (or the
  `combine='nested'` option to open_mfdataset.
    from_openmfds=True,

xarray/tests/test_coding_times.py::test_cf_datetime_nan[num_dates1-days since 2000-01-01-expected_list1]
xarray/tests/test_coding_times.py::test_cf_datetime_nan[num_dates2-days since 2000-01-01-expected_list2]
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/numpy/testing/_private/utils.py:913: FutureWarning: Converting timezone-aware DatetimeArray to timezone-naive ndarray with 'datetime64[ns]' dtype. In the future, this will return an ndarray with 'object' dtype where each element is a 'pandas.Timestamp' with the correct 'tz'.
  	To accept the future behavior, pass 'dtype=object'.
  	To keep the old behavior, pass 'dtype="datetime64[ns]"'.
    verbose=verbose, header='Arrays are not equal')

xarray/tests/test_dataarray.py::TestDataArray::test_drop_index_labels
xarray/tests/test_dataarray.py::TestDataArray::test_drop_index_labels
xarray/tests/test_dataarray.py::TestDataArray::test_drop_index_labels
  /home/vsts/work/1/s/xarray/core/dataarray.py:1842: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    ds = self._to_temp_dataset().drop(labels, dim, errors=errors)

xarray/tests/test_dataset.py::TestDataset::test_drop_index_labels
  /home/vsts/work/1/s/xarray/tests/test_dataset.py:2066: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    actual = data.drop(["a"], "x")

xarray/tests/test_dataset.py::TestDataset::test_drop_index_labels
  /home/vsts/work/1/s/xarray/tests/test_dataset.py:2070: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    actual = data.drop(["a", "b"], "x")

xarray/tests/test_dataset.py::TestDataset::test_drop_index_labels
  /home/vsts/work/1/s/xarray/tests/test_dataset.py:2078: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    data.drop(["c"], dim="x")

xarray/tests/test_dataset.py::TestDataset::test_drop_index_labels
  /home/vsts/work/1/s/xarray/tests/test_dataset.py:2080: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    actual = data.drop(["c"], dim="x", errors="ignore")

xarray/tests/test_dataset.py::TestDataset::test_drop_index_labels
  /home/vsts/work/1/s/xarray/tests/test_dataset.py:2086: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    actual = data.drop(["a", "b", "c"], "x", errors="ignore")

xarray/tests/test_dataset.py::TestDataset::test_drop_labels_by_keyword
  /home/vsts/work/1/s/xarray/tests/test_dataset.py:2135: DeprecationWarning: dropping dimensions using list-like labels is deprecated; use dict-like arguments.
    data.drop(labels=["a"], dim="x", x="a")

xarray/tests/test_dataset.py::TestDataset::test_convert_dataframe_with_many_types_and_multiindex
  /home/vsts/work/1/s/xarray/core/dataset.py:3959: FutureWarning: Converting timezone-aware DatetimeArray to timezone-naive ndarray with 'datetime64[ns]' dtype. In the future, this will return an ndarray with 'object' dtype where each element is a 'pandas.Timestamp' with the correct 'tz'.
  	To accept the future behavior, pass 'dtype=object'.
  	To keep the old behavior, pass 'dtype="datetime64[ns]"'.
    data = np.asarray(series).reshape(shape)

xarray/tests/test_dataset.py::TestDataset::test_convert_dataframe_with_many_types_and_multiindex
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/pandas/core/apply.py:321: FutureWarning: Converting timezone-aware DatetimeArray to timezone-naive ndarray with 'datetime64[ns]' dtype. In the future, this will return an ndarray with 'object' dtype where each element is a 'pandas.Timestamp' with the correct 'tz'.
  	To accept the future behavior, pass 'dtype=object'.
  	To keep the old behavior, pass 'dtype="datetime64[ns]"'.
    results[i] = self.f(v)

xarray/tests/test_distributed.py::test_dask_distributed_cfgrib_integration_test
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/tornado/gen.py:772: RuntimeWarning: deallocating CachingFileManager(<function open at 0x7f2527b49bf8>, '/tmp/tmpt4tmnjh3/temp-2044.tif', mode='r', kwargs={}), but file is not already closed. This may indicate a bug.
    self.future = convert_yielded(yielded)

xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-min-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-False-max-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-True-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-True-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-True-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-True-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-min-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-True-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-True-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-True-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-True-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-float-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-int-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-float32-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-bool_-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-str-1]
xarray/tests/test_duck_array_ops.py::test_argmin_max[x-True-max-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-min-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-False-max-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-False-True-bool_-2]
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xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-min-True-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-False-False-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-True-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-True-str-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-False-float-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-False-int-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-False-float32-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-False-bool_-2]
xarray/tests/test_duck_array_ops.py::test_argmin_max[y-True-max-True-False-str-2]
  /home/vsts/work/1/s/xarray/core/dataarray.py:1842: FutureWarning: dropping coordinates using key values of dict-like labels is deprecated; use drop_vars or a list of coordinates.
    ds = self._to_temp_dataset().drop(labels, dim, errors=errors)

xarray/tests/test_plot.py::TestPlotStep::test_step
  /home/vsts/work/1/s/xarray/plot/plot.py:321: MatplotlibDeprecationWarning: Passing the drawstyle with the linestyle as a single string is deprecated since Matplotlib 3.1 and support will be removed in 3.3; please pass the drawstyle separately using the drawstyle keyword argument to Line2D or set_drawstyle() method (or ds/set_ds()).
    primitive = ax.plot(xplt_val, yplt_val, *args, **kwargs)

xarray/tests/test_print_versions.py::test_show_versions
  /usr/share/miniconda/envs/xarray-tests/lib/python3.7/site-packages/setuptools/depends.py:2: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
    import imp

xarray/tests/test_sparse.py::test_dataarray_method[obj.roll(*(), **{'x': 2})-True]
  /home/vsts/work/1/s/xarray/core/dataarray.py:2632: FutureWarning: roll_coords will be set to False in the future. Explicitly set roll_coords to silence warning.
    shifts=shifts, roll_coords=roll_coords, **shifts_kwargs

xarray/tests/test_sparse.py::TestSparseDataArrayAndDataset::test_ufuncs
  /home/vsts/work/1/s/xarray/tests/test_sparse.py:711: PendingDeprecationWarning: xarray.ufuncs will be deprecated when xarray no longer supports versions of numpy older than v1.17. Instead, use numpy ufuncs directly.
    assert_equal(np.sin(x), xu.sin(x))

xarray/tests/test_sparse.py::TestSparseDataArrayAndDataset::test_ufuncs
  /home/vsts/work/1/s/xarray/core/dataarray.py:2393: PendingDeprecationWarning: xarray.ufuncs will be deprecated when xarray no longer supports versions of numpy older than v1.17. Instead, use numpy ufuncs directly.
    return self.__array_wrap__(f(self.variable.data, *args, **kwargs))

xarray/tests/test_sparse.py::TestSparseDataArrayAndDataset::test_groupby_bins
  /home/vsts/work/1/s/xarray/core/groupby.py:780: FutureWarning: Default reduction dimension will be changed to the grouped dimension in a future version of xarray. To silence this warning, pass dim=xarray.ALL_DIMS explicitly.
    **kwargs

-- Docs: https://docs.pytest.org/en/latest/warnings.html

[ArchangeGabriel]

If people want more, here are some from a fresh compilation: https://paste.xinu.at/LnH/

[ArchangeGabriel]

These are the (much less numerous) warnings without pint:

=============================== warnings summary ===============================
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
xarray/tests/test_accessor_str.py::test_empty_str_methods
  /build/python-xarray/src/xarray-0.15.0/xarray/core/duck_array_ops.py:224: FutureWarning: elementwise comparison failed; returning scalar instead, but in the future will perform elementwise comparison
    flag_array = (arr1 == arr2) | (isnull(arr1) & isnull(arr2))

xarray/tests/test_backends.py::TestNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF3ViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_orthogonal_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_vectorized_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestNetCDF4ClassicViaNetCDF4Data::test_array_type_after_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_orthogonal_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_orthogonal_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_orthogonal_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_orthogonal_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_vectorized_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_array_type_after_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_array_type_after_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_array_type_after_indexing
xarray/tests/test_backends.py::TestGenericNetCDFData::test_array_type_after_indexing
  <__array_function__ internals>:5: DeprecationWarning: `np.alen` is deprecated, use `len` instead

xarray/tests/test_concat.py::test_concat_compat
  /build/python-xarray/src/xarray-0.15.0/xarray/core/dataarray.py:669: FutureWarning: elementwise comparison failed; returning scalar instead, but in the future will perform elementwise comparison
    return key in self.data

xarray/tests/test_dataarray.py::TestDataArray::test_stack_unstack
  /usr/lib/python3.8/site-packages/pandas/util/__init__.py:12: FutureWarning: pandas.util.testing is deprecated. Use the functions in the public API at pandas.testing instead.
    import pandas.util.testing

xarray/tests/test_dataarray.py::TestDataArray::test_to_and_from_empty_series
  /build/python-xarray/src/xarray-0.15.0/xarray/tests/test_dataarray.py:3468: DeprecationWarning: The default dtype for empty Series will be 'object' instead of 'float64' in a future version. Specify a dtype explicitly to silence this warning.
    expected = pd.Series([])

xarray/tests/test_duck_array_ops.py::test_datetime_mean[False]
xarray/tests/test_duck_array_ops.py::test_datetime_mean[False]
xarray/tests/test_groupby.py::test_groupby_drops_nans
  /build/python-xarray/src/xarray-0.15.0/xarray/core/nanops.py:142: RuntimeWarning: Mean of empty slice
    return np.nanmean(a, axis=axis, dtype=dtype)