gem2deb-test-runner failures with ruby-defaults 1:3.3~ubuntu3

[Pushkar Kulkarni]

The autopkgtests of ruby-attr-encrypted that are run by the gem2deb-test-runner fail (e.g: [1]) with ruby-defaults 1:3.3~ubuntu3 due to a change in the behavior of the MiniTest gem. Ruby 3.3 comes with minitest 5.20.00. Startung version 5.19.0, the MiniTest class is no longer loaded by default. Either the use of "MiniTest" needs to be replaced by "Minitest" or env var MT_COMPAT needs to be defined.

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1088s /tmp/autopkgtest.MBvPc8/build.mV3/src/test/test_helper.rb:5:in `<top (required)>': uninitialized constant MiniTest (NameError)
1088s
1088s MiniTest::Test = MiniTest::Unit::TestCase
1088s ^^^^^^^^
1088s Did you mean? Minitest

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[1] https://objectstorage.prodstack5.canonical.com/swift/v1/AUTH_0f9aae918d5b4744bf7b827671c86842/autopkgtest-oracular/oracular/amd64/r/ruby-attr-encrypted/20240820_142215_b81be@/log.gz

[2] https://docs.seattlerb.org/minitest/History_rdoc.html#label-5.19.0+-2F+2023-07-26

[Pushkar Kulkarni (pushkarnk)]

For now, we could wait for upstream projects to switch to using Minitest (instead of MiniTest) while using the MT_COMPAT solution.