TST: Test pd.Grouper base floating point error (#25161)
State: closed

- [x] closes #25161
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`


Labels:
name: Testing
description: pandas testing functions or related to the test suite
name: Datetime
description: Datetime data dtype
name: Groupby

Comments:
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=h1) Report
> Merging [#26240](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/9feb3ad92cc0397a04b665803a49299ee7aa1037?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/26240/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26240      +/-   ##
==========================================
- Coverage   91.97%   91.96%   -0.01%     
==========================================
  Files         175      175              
  Lines       52368    52368              
==========================================
- Hits        48164    48161       -3     
- Misses       4204     4207       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.52% <ø> (ø)` | :arrow_up: |
| #single | `40.69% <ø> (-0.16%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.9% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.71% <0%> (+0.1%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=footer). Last update [9feb3ad...da71a45](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=h1) Report
> Merging [#26240](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/9feb3ad92cc0397a04b665803a49299ee7aa1037?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/26240/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26240      +/-   ##
==========================================
+ Coverage   91.97%   91.97%   +<.01%     
==========================================
  Files         175      175              
  Lines       52368    52386      +18     
==========================================
+ Hits        48164    48181      +17     
- Misses       4204     4205       +1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.52% <ø> (ø)` | :arrow_up: |
| #single | `40.72% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/io/excel/\_base.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2V4Y2VsL19iYXNlLnB5) | `92.13% <0%> (-0.72%)` | :arrow_down: |
| [pandas/core/indexes/datetimelike.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZWxpa2UucHk=) | `98.13% <0%> (-0.4%)` | :arrow_down: |
| [pandas/core/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYmFzZS5weQ==) | `97.98% <0%> (-0.22%)` | :arrow_down: |
| [pandas/plotting/\_core.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb3JlLnB5) | `83.63% <0%> (-0.14%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.9% <0%> (-0.12%)` | :arrow_down: |
| [pandas/tseries/holiday.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvaG9saWRheS5weQ==) | `93.1% <0%> (ø)` | :arrow_up: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `93.54% <0%> (ø)` | :arrow_up: |
| [pandas/core/arrays/period.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYXJyYXlzL3BlcmlvZC5weQ==) | `98.53% <0%> (ø)` | :arrow_up: |
| [pandas/core/groupby/groupby.py](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ3JvdXBieS9ncm91cGJ5LnB5) | `97.23% <0%> (ø)` | :arrow_up: |
| ... and [12 more](https://codecov.io/gh/pandas-dev/pandas/pull/26240/diff?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=footer). Last update [9feb3ad...913dd1c](https://codecov.io/gh/pandas-dev/pandas/pull/26240?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).

thanks @ihsansecer