TST: add concrete examples of dataframe fixtures to docstrings
State: closed

add concrete examples of dataframe fixtures to docstrings to make it easier when looking for fixtures to reuse.

and also appear when using `pytest --fixtures` and `pytest --fixtures-per-test` so could be an aid to debugging

```
------------------ fixtures used by test_set_index_directly -------------------
----------------- (pandas\tests\frame\test_alter_axes.py:20) ------------------
add_imports
    no docstring available
configure_tests
    no docstring available
doctest_namespace
    Fixture that returns a :py:class:`dict` that will be injected into the namespace of doctests.
float_string_frame
    Fixture for DataFrame of floats and strings with index of unique strings

    Columns are ['A', 'B', 'C', 'D', 'foo'].

                       A         B         C         D  foo
    w3orJvq07g -1.594062 -1.084273 -1.252457  0.356460  bar
    PeukuVdmz2  0.109855 -0.955086 -0.809485  0.409747  bar
    ahp2KvwiM8 -1.533729 -0.142519 -0.154666  1.302623  bar
    3WSJ7BUCGd  2.484964  0.213829  0.034778 -2.327831  bar
    khdAmufk0U -0.193480 -0.743518 -0.077987  0.153646  bar
    LE2DZiFlrE -0.193566 -1.343194 -0.107321  0.959978  bar
    HJXSJhVn7b  0.142590  1.257603 -0.659409 -0.223844  bar
    ...              ...       ...       ...       ...  ...
    9a1Vypttgw -1.316394  1.601354  0.173596  1.213196  bar
    h5d1gVFbEy  0.609475  1.106738 -0.155271  0.294630  bar
    mK9LsTQG92  1.303613  0.857040 -1.019153  0.369468  bar
    oOLksd9gKH  0.558219 -0.134491 -0.289869 -0.951033  bar
    9jgoOjKyHg  0.058270 -0.496110 -0.413212 -0.852659  bar
    jZLDHclHAO  0.096298  1.267510  0.549206 -0.005235  bar
    lR0nxDp1C2 -2.119350 -0.794384  0.544118  0.145849  bar

    [30 rows x 5 columns]

```


Labels:
name: Testing
description: pandas testing functions or related to the test suite

Comments:
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=h1) Report
> Merging [#26593](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/7f318658b92155678b31780722277d1f8c8df569?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/26593/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26593      +/-   ##
==========================================
- Coverage   91.84%   91.84%   -0.01%     
==========================================
  Files         174      174              
  Lines       50644    50644              
==========================================
- Hits        46516    46512       -4     
- Misses       4128     4132       +4
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.37% <ø> (ø)` | :arrow_up: |
| #single | `41.68% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26593/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/26593/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97% <0%> (-0.12%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26593?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/26593?src=pr&el=footer). Last update [7f31865...f109c21](https://codecov.io/gh/pandas-dev/pandas/pull/26593?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/26593?src=pr&el=h1) Report
> Merging [#26593](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/7f318658b92155678b31780722277d1f8c8df569?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/26593/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26593      +/-   ##
==========================================
- Coverage   91.84%   91.84%   -0.01%     
==========================================
  Files         174      174              
  Lines       50644    50644              
==========================================
- Hits        46516    46512       -4     
- Misses       4128     4132       +4
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.37% <ø> (ø)` | :arrow_up: |
| #single | `41.68% <ø> (-0.12%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26593/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/26593/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97% <0%> (-0.12%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26593?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/26593?src=pr&el=footer). Last update [7f31865...f109c21](https://codecov.io/gh/pandas-dev/pandas/pull/26593?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).

thanks @simonjayhawkins