Ruby Test Frameworks

Minitest vs Test-Unit Divergences

Only covers where minitest and test-unit diverge. If something isn't listed here, it works the same in both.

Assertion Naming Mismatches

Using the wrong name causes NoMethodError.

test-unit aliases minitest names (assert_raises, refute_*, etc.), so minitest syntax works in test-unit but not vice versa.

Assertions That Only Exist in One Framework

test-unit only

minitest only

minitest 6 breaking change

assert_equal(nil, value) is a hard failure in minitest 6. Use assert_nil(value) instead. test-unit has no such restriction.

Test Selection (CLI Flags)

minitest 6 renamed -n to -i (--include). -n still works as an alias but is planned for removal.

Rails-specific flags (minitest underneath)

bin/rails test adds: -b (full backtrace), -f (fail-fast), -d (defer output), --profile [N] (slowest tests).

Lifecycle Differences

minitest

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before_setup    (for frameworks like Rails)
  setup         (for test authors)
    after_setup
      [TEST]
    before_teardown
  teardown
after_teardown

No class-level hooks. No cleanup. For before(:all) / after(:all), use the minitest-hooks gem.

test-unit

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startup           (class method, once before all tests)
  setup           (instance, before each test)
    [TEST]
  cleanup         (instance, only if test didn't raise)
  teardown        (instance, always runs, even if cleanup raised)
shutdown          (class method, once after all tests)

startup/shutdown have no minitest equivalent. cleanup runs after a passing test but before it's marked as passed — use it for verification like mock expectations. teardown always runs regardless of outcome — use it for resource release.

test-unit also supports registering multiple setup/teardown methods by symbol:

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setup :prepare_database, :prepare_cache

Skip / Pending / Omit

Critical difference: test-unit's pend with a block fails if the block passes. This catches code that was fixed but still marked pending. minitest's skip is always unconditional.

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# test-unit: this FAILS if the bug gets fixed
pend("Bug #123") do
  assert_equal(42, buggy_method)  # if this passes, test fails
end

# minitest: no equivalent behavior
skip("Bug #123")  # always skips, no block form

Output Format

test-unit Exclusive Features

These have no minitest equivalent:

• Data-driven tests: data("label", value) method generates parameterized test runs
• Priority system: priority :must / :important / :high / :normal / :low / :never with probabilistic execution
• Attributes: Generic metadata on test methods, filterable via --attribute
• sub_test_case: Named nested test groups (minitest uses describe blocks in Spec mode)
• notify: Non-fatal informational messages shown as N in output
• Test runners: Console, Emacs, XML (minitest only has console with plugin system)
• Config file: ~/.test-unit.yml for persistent settings

Rails Context

Rails uses minitest, not test-unit. But Rails adds aliases and methods that blur the line:

Aliases Rails defines on top of minitest:

Methods Rails adds (not in either framework):

This means in Rails: assert_not_nil, assert_raise, and assert_nothing_raised all work — but they will not work if you move the test to plain minitest outside Rails.