About

A minitest-compatible testing framework for mruby. It covers the core minitest API: test classes, assertions, spec DSL, and expectations.

Features

mruby-minitest is an mrbgem that ports the essential parts of minitest to mruby:

• Minitest::Test with setup/teardown lifecycle
• Assertions: assert_equal, assert_raises, assert_nil, assert_match, assert_in_delta, assert_predicate, assert_operator, flunk, skip, pass, and all refute_* counterparts
• Spec DSL: describe/it blocks, before/after hooks, let/subject
• Expectations: must_equal, must_include, must_raise, must_match, wont_equal, wont_include, etc.
• Explicit runner: call Minitest.run(ARGV) at the bottom of your test file (mruby does not have at_exit, so no autorun)
• Reporters: dot-based progress and summary output

Example

# test/calculator_test.rb

class TestCalculator < Minitest::Test
  def setup
    @calc = 1
  end

  def test_adds
    assert_equal 3, @calc + 2
  end
end

Minitest.run(ARGV) || exit(1)

Or spec-style:

describe "Array" do
  it "includes elements" do
    _([1, 2, 3]).must_include 2
  end

  it "is empty" do
    _([]).must_be :empty?
  end
end

Minitest.run(ARGV) || exit(1)

Integration

Add to your mruby build config:

MRuby::Build.new("mruby-minitest") do |conf|
  conf.toolchain
  conf.gembox "default"
  conf.gem github: "0x1eef/mruby-minitest", branch: "main"
  conf.enable_debug
end

Dependencies are declared in mrbgem.rake. The only external dependency is mruby-stringio (for capture_io / assert_output).

API Coverage

Included

Feature	Status
Minitest::Test with test_* discovery	✅
setup / teardown lifecycle	✅
assert / refute	✅
assert_equal / refute_equal	✅
assert_nil / refute_nil	✅
assert_raises	✅
assert_in_delta / refute_in_delta	✅
assert_match / refute_match	✅
assert_includes / refute_includes	✅
assert_predicate / refute_predicate	✅
assert_operator / refute_operator	✅
assert_respond_to / refute_respond_to	✅
assert_instance_of / refute_instance_of	✅
assert_kind_of / refute_kind_of	✅
assert_same / refute_same	✅
assert_empty / refute_empty	✅
assert_output / capture_io	✅ (with stringio)
assert_silent	✅ (with stringio)
assert_throws / catch	✅
skip / flunk / pass	✅
describe / it / specify	✅
before / after hooks	✅
let / subject	✅
Expectations (must_* / wont_*)	✅
Minitest.run(ARGV)	✅
SEED / --seed / --verbose / --name	✅

Not Included

Feature	Reason
Auto-run (at_exit)	mruby does not have at_exit; call Minitest.run(ARGV)
Parallel execution	No Thread in mruby
Diff output	Needs Tempfile + external diff
Plugin auto-discovery	No Rubygems
INFO signal handler	No Signal/trap in mruby
Marshal-based exception sanitization	No Marshal in mruby
Bisect / Sprint / Server	Niche features
Benchmark	Separate gem (mruby-benchmark exists)
Pride output	Pure cosmetic, could add easily

Origins

Motivation

I wanted a familiar test framework to write tests for mruby-llm and minitest appeared to be a good candidate. The tests for llm.rb are written in RSpec, and porting those tests to mruby-minitest is more or less straight forward.

Workflow

I used relay.app and DeepSeek v4 to analyze both the minitest and mruby repositories over a local Forgejo MCP server. The analysis determined what could and couldn't be ported to mruby, and afterwards it created a repository that implemented the port. It wasn't perfect but served as a good foundation.

No new code was generated per se, it was more like copying the existing parts of minitest that were portable and dropping what wasn't. The code itself is minitest, just optimized to include only those parts that can work on mruby.

Additions

• toplevel: add context as an alias of describe
• DSL: add DSL#{describe,context}

License

MIT