Update minitest requirement from ~> 5.0 to ~> 6.0

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Updates the requirements on minitest to permit the latest version.

Changelog

Sourced from minitest's changelog.

=== 6.0.1 / 2025-12-26

• 1 minor enhancement:

  • Added new rake task test:fu to Minitest::TestTask, to only run tests with FU (focused units?) in their name. This should mostly obviate the need for the minitest-focus plugin.

• 5 bug fixes:

  • Fixed --help and --version exiting 1. (grosser)
  • Fixed method signature of Minitest::Benchmark.run. (flavorjones)
  • Flush stdout/stderr before exit./bin/minitest -Ilib ./bug1046.rb:1 < /dev/null (grosser)
  • Improved usage banner output by reordering and reformatting.
  • Normalize paths while processing file.rb:line args.

=== 6.0.0 / 2025-12-17

This is a major release. Read this.

Please give feedback here: minitest/minitest#1040

Oh god... here we go... (again)

• 8 deaths in the family(!!):

  • Deleted MiniTest and MiniTest::Unit::TestCase compatibility namespaces.
  • Deleted all use of Marshal for serialization.
  • Deleted maglev? and rubinius? guard methods. LOL.
  • Deleted all minitest/spec expectations from Object. Use _/value/expect.
  • Dropped minitest/mock.rb. This has been extracted to the minitest-mock gem.
  • assert_equal(nil, value) no longer allowed. Use assert_nil to be explicit.
  • Removed assert_send. Use assert_predicate or assert_operator.
  • Removed Minitest::Test#class_name.

• 7 major (oft incompatible) changes:

  • Big: Major refactored MT6's run path!
    • Minitest.__run -> Minitest.run_all_suites
    • Runnable.run -> Runnable.run_suite & Runnable.filter_runnable_methods
    • Runnable.run_one_method -> Runnable.run
    • Removed Minitest.run_one_method (might bring it back to raise?)
  • Removed deprecated ENV["N"] to specify number of parallel tests. Use MT_CPU.
  • Renamed +options[:filter]+ to +options[:include]+, added --include cmdline option.
    • --name is still handled, but that will be removed in the future.
  • Renamed Minitest::Runnable#test_order to #run_order.
  • If #message is passed a proc then that proc overrides all other output.
    • They are no longer chained!
    • And it does less for formatting of your output.
  • Removed reporter arg from with_info_handler as it has never(?) been used. (HACK?)

... (truncated)

Commits

• edd37ce prepped for release
• 248c9e2 - Fixed method signature of Minitest::Benchmark.run. (flavorjones)
• 18bbdb1 - Flush stdout/stderr before exit./bin/minitest -Ilib ./bug1046.rb:1 < /dev/n...
• 50a1b1f - Normalize paths while processing file.rb:line args.
• 372b997 - Fixed --help and --version exiting 1. (grosser)
• c05a898 - Improved usage banner output by reordering and reformatting.
• 692c2e7 + Added new rake task test:fu to Minitest::TestTask, to only run tests with...
• 5bbab5c Fix format of History.rdoc. (y-yagi)
• 2f3d88e prepped for release
• 756f965 Add Hoe's :cov plugin and start to look at gaps
• Additional commits viewable in compare view

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[Copilot]

Pull request overview

Updates this gem’s development dependency constraint for minitest to allow the latest major version (6.x), aligning the repo’s test tooling with the newest Minitest release.

Changes:

• Bump minitest development dependency from ~> 5.0 to ~> 6.0.

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[Copilot]

Minitest 6 removed minitest/mock (extracted to the minitest-mock gem). This repo currently requires minitest/mock in test/test_helper.rb and uses Minitest::Mock in multiple tests, so bumping to ~> 6.0 will break the test suite unless minitest-mock is added as a development dependency (or the tests are updated to avoid it).

Suggested change

	spec.add_development_dependency "minitest", "~> 6.0"
	spec.add_development_dependency "minitest", "~> 6.0"
	spec.add_development_dependency "minitest-mock"