Measure the code coverage and upload reports

[nolar]

Issue : closes #99, previously #13

(Playing with CodeCov and branches, need the real PR for this.)

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Tools:

Few tools are enabled for the same coverage measurements. More can be added over time — to compare and to use the benefits of all of them.

• CodeCov: https://codecov.io/gh/zalando-incubator/kopf (nice graphs, no if-branch coverage).
• Coveralls: https://coveralls.io/github/zalando-incubator/kopf (if-branch coverage, poor graphs).

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Historic measurements:

The code coverage measurements for CodeCov were replayed for the whole git log — i.e. every commit — to render the graph nicely.

Coveralls does not date the coverage uploads to the commit timestamps (or it seems so), so it makes no sense to replay.

The ad-hoc script for replaying the history is here: https://gist.github.com/nolar/35c73e7a0caa37a30f0a37bdebb5d574

[zincr]

🤖 zincr found 0 problems , 1 warning

ℹ️ Dependency Licensing
✅ Large Commits
✅ Approvals
✅ Specification

Details on how to resolve are provided below

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Dependency Licensing

All dependencies specified in package manager files must be reviewed, banned dependency licenses will block the merge, all new dependencies introduced in this pull request will give a warning, but not block the merge

Please ensure that only dependencies with licenses compatible with the license of this project is included in the pull request.

• ℹ️ Could not process requirements.txt for new dependencies
   

[zincr]

🤖 zincr found 1 problem , 1 warning

❌ Approvals
ℹ️ Dependency Licensing
✅ Large Commits
✅ Specification

Details on how to resolve are provided below

---

Approvals

All proposed changes must be reviewed by project maintainers before they can be merged

Not enough people have approved this pull request - please ensure that 1 additional user, who have not contributed to this pull request approve the changes.

• ✅ Approved by PR author @nolar
• ❌ 1 additional approval needed
   

Dependency Licensing

All dependencies specified in package manager files must be reviewed, banned dependency licenses will block the merge, all new dependencies introduced in this pull request will give a warning, but not block the merge

Please ensure that only dependencies with licenses compatible with the license of this project is included in the pull request.

• ℹ️ Could not process requirements.txt for new dependencies
   

[codecov-io]

Codecov Report

❗ No coverage uploaded for pull request base (master@130d3a4). Click here to learn what that means.
The diff coverage is n/a.

@@            Coverage Diff            @@
##             master      #72   +/-   ##
=========================================
  Coverage          ?   63.14%           
=========================================
  Files             ?       21           
  Lines             ?     1080           
  Branches          ?      152           
=========================================
  Hits              ?      682           
  Misses            ?      385           
  Partials          ?       13

Flag	Coverage Δ
#e2e	63.14% <ø> (?)
#unit	63.14% <ø> (?)

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Continue to review full report at Codecov.

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[codecov-io]

Codecov Report

Merging #72 into master will increase coverage by 0.23%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #72      +/-   ##
==========================================
+ Coverage   83.81%   84.04%   +0.23%     
==========================================
  Files          29       29              
  Lines        1433     1454      +21     
  Branches      211      212       +1     
==========================================
+ Hits         1201     1222      +21     
  Misses        194      194              
  Partials       38       38

Impacted Files	Coverage Δ
kopf/clients/fetching.py	100% <0%> (ø)	⬆️
kopf/reactor/registries.py	89.58% <0%> (+0.37%)	⬆️
kopf/engines/peering.py	28.34% <0%> (+0.56%)	⬆️
kopf/cli.py	87.09% <0%> (+1.13%)	⬆️
kopf/testing/runner.py	81.57% <0%> (+2.16%)	⬆️