id,node_id,number,title,user,state,locked,assignee,milestone,comments,created_at,updated_at,closed_at,author_association,active_lock_reason,draft,pull_request,body,reactions,performed_via_github_app,state_reason,repo,type
922843005,MDExOlB1bGxSZXF1ZXN0NjcxNjY5NjU0,5476,Add coarsen.construct,2448579,closed,0,,,4,2021-06-16T16:42:15Z,2021-07-23T20:26:38Z,2021-06-24T16:55:25Z,MEMBER,,0,pydata/xarray/pulls/5476,"<!-- Feel free to remove check-list items aren't relevant to your change -->

- [x] Closes #5454
- [x] Tests added
- [x] Passes `pre-commit run --all-files`
- [x] User visible changes (including notable bug fixes) are documented in `whats-new.rst`
- [x] New functions/methods are listed in `api.rst`

Builds on #5474 

Here's an example
``` python
import numpy as np
import xarray as xr

ds = xr.Dataset(
    {
        ""vart"": (""time"", np.arange(48)),
        ""varx"": (""x"", np.arange(10)),
        ""vartx"": ((""x"", ""time""), np.arange(480).reshape(10, 48)),
        ""vary"": (""y"", np.arange(12)),
    },
    coords={""time"": np.arange(48), ""y"": np.arange(12)},
)
ds.coarsen(time=12, x=5, boundary=""trim"").construct(
    {""time"": (""year"", ""month""), ""x"": (""x"", ""x_reshaped"")}
)
```

What do people think of this syntax:  `{""time"": (""year"", ""month""), ""x"": (""x"", ""x_reshaped"")`? Should we instead do `{""time"": ""month"", ""x"": ""x_reshaped""}` and have the user later rename the `x` or `time` dimension if they want?","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5476/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull
922792799,MDExOlB1bGxSZXF1ZXN0NjcxNjI1NDc3,5474,Refactor out coarsen tests,2448579,closed,0,,,3,2021-06-16T15:52:57Z,2021-06-21T17:04:02Z,2021-06-21T16:35:36Z,MEMBER,,0,pydata/xarray/pulls/5474,"<!-- Feel free to remove check-list items aren't relevant to your change -->

- xref #5409
- [x] Tests added
- [x] Passes `pre-commit run --all-files`

Some questions:
1. flake8 fails with some false positives. What do we do about that? 
2. I am importing the `da` and `ds` fitures from `test_dataarray` and `test_dataset`. Is that the pattern we want to follow?

```
xarray/tests/test_coarsen.py:9:1: F401 '.test_dataarray.da' imported but unused
xarray/tests/test_coarsen.py:10:1: F401 '.test_dataset.ds' imported but unused
xarray/tests/test_coarsen.py:13:36: F811 redefinition of unused 'ds' from line 10
xarray/tests/test_coarsen.py:20:26: F811 redefinition of unused 'ds' from line 10
xarray/tests/test_coarsen.py:35:25: F811 redefinition of unused 'ds' from line 10
xarray/tests/test_coarsen.py:51:5: F811 redefinition of unused 'da' from line 9
xarray/tests/test_coarsen.py:62:5: F811 redefinition of unused 'da' from line 9
xarray/tests/test_coarsen.py:84:5: F811 redefinition of unused 'ds' from line 10
xarray/tests/test_coarsen.py:156:5: F811 redefinition of unused 'ds' from line 10
xarray/tests/test_coarsen.py:186:25: F811 redefinition of unused 'ds' from line 10
xarray/tests/test_coarsen.py:217:5: F811 redefinition of unused 'da' from line 9
xarray/tests/test_coarsen.py:269:5: F811 redefinition of unused 'da' from line 9
```
","{""url"": ""https://api.github.com/repos/pydata/xarray/issues/5474/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,,13221727,pull