tests!

On it! Clearly new to TDD but will take a stab.

contributing guide

Current coverage is 84.56% (diff: 100%)

Merging #13757 into master will increase coverage by <.01%

@@             master     #13757   diff @@
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  Files           141        141          
  Lines         51195      51196     +1   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
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+ Hits          43295      43296     +1   
  Misses         7900       7900          
  Partials          0          0          

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this need to address #13503 which is the main issue.

Are you saying that if I resolve the issue in #13503 then it will also automatically address the issue in #13753? It looks like #13503 is related to how .count() is implemented for .rolling. However, in my .expanding example, I am using .sum(). It would be helpful if you could point me in the right direction or which class to make changes in. Perhaps, in Rolling?

yes it's the same issue and is addressed in the same place

put tests in place first

pls reopen if you'd like to update