spec: integration tests

[ghost]

We have already moved the legacy tests to a folder called integration, because we want to use them for real integration tests against the Hetzner API. This PR applies the necessary changes to the existing tests so that they run successfully in a non-empty cloud project.

Closes #61

[codecov-commenter]

Codecov Report

Merging #69 (7e114c1) into master (170a91a) will decrease coverage by 0.18%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #69      +/-   ##
==========================================
- Coverage   98.42%   98.24%   -0.19%     
==========================================
  Files         119       96      -23     
  Lines        4266     2627    -1639     
==========================================
- Hits         4199     2581    -1618     
+ Misses         67       46      -21     

Impacted Files	Coverage Δ
lib/hcloud/abstract_resource.rb	88.99% <0.00%> (-9.18%)	⬇️
lib/hcloud/typhoeus_ext.rb	86.20% <0.00%> (-3.45%)	⬇️
lib/hcloud/client.rb	95.78% <0.00%> (-3.16%)	⬇️
spec/integration/datacenter_spec.rb
spec/integration/firewall_spec.rb
spec/integration/iso_spec.rb
spec/integration/location_spec.rb
spec/integration/network_spec.rb
spec/integration/server_spec.rb
spec/integration/server_type_spec.rb
... and 1 more

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[ghost]

@tonobo @Kjarrigan Works now, you can have a look at it when you have time. I'll leave the PR as "Draft", because before we merge I want to switch back on: push to on: workflow_dispatch. I would not want the integration test to automatically run on each push.

There are some not so nice segments in the code, maybe you know something better?

I want to allow multiple test runs in parallel, thus I am generating a unique ID. Had to use a global variable to persist it across examples :/

  def resource_name(name)
    # use a random ID to allow multiple CI runs in parallel
    $random_resource_name_id ||= Random.rand(10_000..99_999)
    "hcloud-ruby-integration-#{$random_resource_name_id}-#{name}"
  end

And some resources (floating IPs, images) do not allow easy access by name. Normally, I can delete the resources at the end of the test run by using the names, but floating IPs and images only have descriptions, so I need to delete them by ID. I am thus saving the IDs of generated resources to a instance variable @ids to be able to delete them at the end. That also feels a bit strange.

[ghost]

@tonobo Can you delete or unprotect my branch integration-tests? I can just repush it, so deletion is no problem. I rebased and want to remove the commit test integration tests within PR, so that we can merge. But Github forbids a force-push to the branch.