Block all network traffic when using VCR cassettes for unit tests

[valgur]

Disable the socket.socket interface to block all network traffic when running unit tests against prerecorded queries. This should make writing unit tests a bit easier by explicitly enforcing our convention of not doing any network requests by default when running unit tests.

I wanted to add this very minor enhancement already about a year ago, but the pytest-socket extension needed some tweaking first for this to work in a reasonable manner.

[kr-stn]

Should we document this somewhere, so people writing new tests are not caught off-guard? Or do you think the documentation of the usage of VCR and how to record new responses is enough?

I tend towards the latter.

[codecov]

Codecov Report

Merging #207 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #207   +/-   ##
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  Coverage   95.36%   95.36%           
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  Files           3        3           
  Lines         539      539           
  Branches      110      110           
=======================================
  Hits          514      514           
  Misses         16       16           
  Partials        9        9

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[valgur]

Good point. The exception raised in case of inadvertent network accesses is not really super clear about its intended purpose (pytest_socket.SocketBlockedError: A test tried to use socket.socket.), so I added a small explanation of this feature to CONTRIBUTE.rst.

[kr-stn]

Perfect 👍