issue_comments: 349149824

any suggestions on comprehensive ways to test things?

I still don't understand what actually went wrong here. It looks like we have test coverage for calling compute on an xarray.DataArray (see test_dataarray_with_dask_coords), but even though the exact example from that test fails at the repl the test passes when called with pytest: ``` In [5]: import xarray as xr

In [6]: import numpy as np

In [7]: import dask

In [8]: import dask.array as da

In [9]: import toolz ...: x = xr.Variable('x', da.arange(8, chunks=(4,))) ...: y = xr.Variable('y', da.arange(8, chunks=(4,)) * 2) ...: data = da.random.random((8, 8), chunks=(4, 4)) + 1 ...: array = xr.DataArray(data, dims=['x', 'y']) ...: array.coords['xx'] = x ...: array.coords['yy'] = y ...: ...: assert dict(array.dask_graph()) == toolz.merge(data.dask_graph(), ...: x.dask_graph(), ...: y.dask_graph()) ...: ...: (array2,) = dask.compute(array) ...:

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ValueError Traceback (most recent call last) <ipython-input-9-4aaee405bed6> in <module>() 11 y.dask_graph()) 12 ---> 13 (array2,) = dask.compute(array)

~/conda/envs/xarray-py36/lib/python3.6/site-packages/dask/base.py in compute(args, kwargs) 334 results_iter = iter(results) 335 return tuple(a if f is None else f(next(results_iter), a) --> 336 for f, a in postcomputes) 337 338

~/conda/envs/xarray-py36/lib/python3.6/site-packages/dask/base.py in <genexpr>(.0) 334 results_iter = iter(results) 335 return tuple(a if f is None else f(next(results_iter), *a) --> 336 for f, a in postcomputes) 337 338

~/dev/xarray/xarray/core/dataarray.py in _dask_finalize(results, func, args, name) 607 @staticmethod 608 def _dask_finalize(results, func, args, name): --> 609 ds = func(results, *args) 610 variable = ds._variables.pop(_THIS_ARRAY) 611 coords = ds._variables

~/dev/xarray/xarray/core/dataset.py in _dask_postcompute(results, info, args) 551 func, args2 = v 552 r = results2.pop() --> 553 result = func(r, args2) 554 else: 555 result = v

~/dev/xarray/xarray/core/variable.py in _dask_finalize(results, array_func, array_args, dims, attrs, encoding) 389 results = {k: v for k, v in results.items() if k[0] == name} # cull 390 data = array_func(results, *array_args) --> 391 return Variable(dims, data, attrs=attrs, encoding=encoding) 392 393 @property

~/dev/xarray/xarray/core/variable.py in init(self, dims, data, attrs, encoding, fastpath) 267 """ 268 self._data = as_compatible_data(data, fastpath=fastpath) --> 269 self._dims = self._parse_dimensions(dims) 270 self._attrs = None 271 self._encoding = None

~/dev/xarray/xarray/core/variable.py in _parse_dimensions(self, dims) 431 raise ValueError('dimensions %s must have the same length as the ' 432 'number of data dimensions, ndim=%s' --> 433 % (dims, self.ndim)) 434 return dims 435

ValueError: dimensions ('x',) must have the same length as the number of data dimensions, ndim=0 ```