Use RESTRICT instead of CASCADE when truncating with postgres

[bsuchodolski]

So the problem was described in this issue #57

In case of two tables, from which one was referencing another, when only referenced table was set to be truncated (e.g. with only option) then referencing table was silently truncated as well because of how postgres's TRUNCATE works with CASCADE option:

Automatically truncate all tables that have foreign-key references to any of the named tables, or to any tables added to the group due to CASCADE.

In case of applications with complex database schema it was easy to stumble upon a problem when such referencing table was truncated despite it was not named to truncate and it was really hard to tell why at the first glance.

With RESTRICT option truncation fails with an exception with clear message about what is the problem and which tables are referencing each another.

[codecov]

Codecov Report

Merging #58 (288ea61) into main (cd18900) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 288ea61 differs from pull request most recent head 4918122. Consider uploading reports for the commit 4918122 to get more accurate results

@@            Coverage Diff            @@
##              main       #58   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
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  Files           12        12           
  Lines          535       549   +14     
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+ Hits           535       549   +14     

Impacted Files	Coverage Δ
lib/database_cleaner/active_record/truncation.rb	100.00% <100.00%> (ø)
.../database_cleaner/active_record/truncation_spec.rb	100.00% <100.00%> (ø)
spec/support/database_helper.rb	100.00% <100.00%> (ø)

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[bsuchodolski]

Hey @botandrose the only thing I cannot figure out is how and to what number bump the version of the gem?

[botandrose]

@bsuchodolski Thanks for putting this together! Don't worry about bumping the version, I'll do that when I release v2.0.1

[GoktugOzturk]

You should use RESTRICT if table names are defined. Otherwise, CASCADE is the only option to truncate multiple tables with default behavior.

Our tests broke because of this change.

  PG::FeatureNotSupported: ERROR:  cannot truncate a table referenced in a foreign key constraint
  DETAIL:  Table "teams" references "events".
  HINT:  Truncate table "teams" at the same time, or use TRUNCATE ... CASCADE.