feat(test): add test command skeleton (#720)

[ajclyall]

Closes #719

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 58.81%. Comparing base (9a4dfc2) to head (8c56960). Report is 7 commits behind head on master.

Files	Patch %	Lines
reana_client/cli/test.py	92.30%	1 Missing :warning:

Additional details and impacted files

[](https://app.codecov.io/gh/reanahub/reana-client/pull/720?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=reanahub) ```diff @@ Coverage Diff @@ ## master #720 +/- ## ========================================== + Coverage 58.62% 58.81% +0.18% ========================================== Files 24 25 +1 Lines 2393 2406 +13 ========================================== + Hits 1403 1415 +12 - Misses 990 991 +1 ``` | [Files](https://app.codecov.io/gh/reanahub/reana-client/pull/720?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=reanahub) | Coverage Δ | | |---|---|---| | [reana\_client/cli/\_\_init\_\_.py](https://app.codecov.io/gh/reanahub/reana-client/pull/720?src=pr&el=tree&filepath=reana_client%2Fcli%2F__init__.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=reanahub#diff-cmVhbmFfY2xpZW50L2NsaS9fX2luaXRfXy5weQ==) | `61.70% <100.00%> (ø)` | | | [reana\_client/cli/test.py](https://app.codecov.io/gh/reanahub/reana-client/pull/720?src=pr&el=tree&filepath=reana_client%2Fcli%2Ftest.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=reanahub#diff-cmVhbmFfY2xpZW50L2NsaS90ZXN0LnB5) | `92.30% <92.30%> (ø)` | |

[mdonadoni]

Closing in favor of https://github.com/reanahub/reana-client/pull/724