issue_comments: 235575744

Ok, I wrote a Dataset.from_dict class method. I imagine the DataArray one will look pretty similar, so I just wanted to see what you think. The main issue that I see is that time doesn't round trip. I wasn't sure if the user should need to set a parse_date flag with the dim name or something or whether the function should try to convert to time any dim with the string 'time' in it?

``` @classmethod def from_dict(cls, d): """ Convert a dictionary into an xarray.Dataset. """ obj = cls()

    dims=OrderedDict([(k, d['coords'][k]) for k in d['dims']])
    for dim, dim_d in dims.items():
        obj[dim] = (dim_d['dims'], dim_d['data'], dim_d['attrs'])

    for var, var_d in d['data_vars'].items():
        obj[var] = (var_d['dims'], var_d['data'], var_d['attrs'])

    # what it coords aren't dims?
    coords = (set(d['coords'].keys()) - set(d['dims']))
    for coord in coords:
        coord_d = d['coords'][coord]
        obj[coord] = (coord_d['dims'], coord_d['data'], coord_d['attrs'])
    obj = obj.set_coords(coords)

    obj.attrs.update(d['attrs'])

    return(obj)

```

Regarding unit tests, I haven't ever written one before but I would be happy to try (I know they are an important part of good development).