TST: ujson tests are not being run (#16499)
add Test prefix on classes to enable PyTest picking them up.
add underscore in test method where applicable.  E.G. testBool() to test_Bool().

 - [X] closes #16499
 - [X] tests added / passed
 - [X] passes ``git diff upstream/master --name-only -- '*.py' | flake8 --diff``
 - [ ] whatsnew entry
lgtm. ping on green. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=h1) Report
> Merging [#16500](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/e81f3cc30725443a1d36ec27279f3fec4eed60ec?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/16500/graphs/tree.svg?height=150&src=pr&token=eZ4WkYLtcO&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16500      +/-   ##
==========================================
+ Coverage   90.43%   90.43%   +<.01%     
==========================================
  Files         161      161              
  Lines       51045    51045              
==========================================
+ Hits        46161    46162       +1     
+ Misses       4884     4883       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.27% <ø> (ø)` | :arrow_up: |
| #single | `40.16% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `62.22% <0%> (+0.44%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16500?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/16500?src=pr&el=footer). Last update [e81f3cc...5026a8d](https://codecov.io/gh/pandas-dev/pandas/pull/16500?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/16500?src=pr&el=h1) Report
> Merging [#16500](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/e81f3cc30725443a1d36ec27279f3fec4eed60ec?src=pr&el=desc) will **increase** coverage by `0.36%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16500/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&height=150&width=650)](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16500      +/-   ##
==========================================
+ Coverage   90.43%   90.79%   +0.36%     
==========================================
  Files         161      161              
  Lines       51045    51063      +18     
==========================================
+ Hits        46161    46365     +204     
+ Misses       4884     4698     -186
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.63% <ø> (+0.36%)` | :arrow_up: |
| #single | `40.15% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.23% <0%> (-1.82%)` | :arrow_down: |
| [pandas/core/categorical.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY2F0ZWdvcmljYWwucHk=) | `95.5% <0%> (-0.42%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.66% <0%> (-0.03%)` | :arrow_down: |
| [pandas/core/reshape/pivot.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzaGFwZS9waXZvdC5weQ==) | `95.08% <0%> (ø)` | :arrow_up: |
| [pandas/core/resample.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvcmVzYW1wbGUucHk=) | `96.09% <0%> (+0.01%)` | :arrow_up: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `92.26% <0%> (+0.09%)` | :arrow_up: |
| [pandas/core/series.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc2VyaWVzLnB5) | `94.9% <0%> (+0.18%)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `80.98% <0%> (+0.19%)` | :arrow_up: |
| [pandas/io/parsers.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2lvL3BhcnNlcnMucHk=) | `95.66% <0%> (+0.32%)` | :arrow_up: |
| [pandas/compat/\_\_init\_\_.py](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree#diff-cGFuZGFzL2NvbXBhdC9fX2luaXRfXy5weQ==) | `62.22% <0%> (+0.44%)` | :arrow_up: |
| ... and [3 more](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=tree-more) | |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16500?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/16500?src=pr&el=footer). Last update [e81f3cc...a74afa1](https://codecov.io/gh/pandas-dev/pandas/pull/16500?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 looks like a linting error (the 2.7 build), ignore the fail on 3.6. ping on green. thanks!