Minitest

# bad
assert(object.empty?)
assert(object.empty?, 'message')

# good
assert_empty(object)
assert_empty(object, 'message')

# bad
assert_equal([], object)
assert_equal({}, object)

# good
assert_empty(object)

# bad
assert("rubocop-minitest" == actual)

# good
assert_equal("rubocop-minitest", actual)

# bad
assert_equal(0.2, actual)
assert_equal(0.2, actual, 'message')

# good
assert_in_delta(0.2, actual)
assert_in_delta(0.2, actual, 0.001, 'message')

# bad
assert(collection.include?(object))
assert(collection.include?(object), 'message')

# good
assert_includes(collection, object)
assert_includes(collection, object, 'message')

# bad
assert(object.instance_of?(Class))
assert(object.instance_of?(Class), 'message')

# good
assert_instance_of(Class, object)
assert_instance_of(Class, object, 'message')

# bad
assert(object.kind_of?(Class))
assert(object.kind_of?(Class), 'message')

# good
assert_kind_of(Class, object)
assert_kind_of(Class, object, 'message')

# bad
assert(matcher.match(string))
assert(matcher.match(string), 'message')

# good
assert_match(regex, string)
assert_match(matcher, string, 'message')

# bad
assert_equal(nil, actual)
assert_equal(nil, actual, 'message')
assert(object.nil?)
assert(object.nil?, 'message')
assert_predicate(object, :nil?)
assert_predicate(object, :nil?, 'message')

# good
assert_nil(actual)
assert_nil(actual, 'message')

# bad
$stdout = StringIO.new
puts object.method
$stdout.rewind
assert_match expected, $stdout.read

# good
assert_output(expected) { puts object.method }

# bad
assert(File.exist?(path))
assert(File.exist?(path), 'message')

# good
assert_path_exists(path)
assert_path_exists(path, 'message')

# bad
assert(obj.one?)
assert(obj.one?, 'message')

# good
assert_predicate(obj, :one?)
assert_predicate(obj, :one?, 'message')

# bad
assert_raises(MyError) do
  foo
  bar
end

# good
assert_raises(MyError) do
  foo
end

# good
assert_raises(MyError) do
  foo do
    bar
    baz
  end
end

# bad
assert_raises FooError, /some message/ do
  obj.occur_error
end

# good
exception = assert_raises FooError do
  obj.occur_error
end
assert_match(/some message/, exception.message)

# bad
assert(object.respond_to?(:do_something))
assert(object.respond_to?(:do_something), 'message')
assert(respond_to?(:do_something))

# good
assert_respond_to(object, :do_something)
assert_respond_to(object, :do_something, 'message')
assert_respond_to(self, :do_something)

# bad
assert(expected.equal?(actual))

# good
assert_same(expected, actual)

# bad
assert_output('', '') { puts object.do_something }

# good
assert_silent { puts object.do_something }

assert_equal(true, 'truthy') # failure
assert('truthy')             # success

# bad
assert_equal(true, actual)
assert_equal(true, actual, 'message')

# good
assert(actual)
assert(actual, 'message')

# bad
assert(3, my_list.length)
assert(expected, actual)

# good
assert_equal(3, my_list.length)
assert_equal(expected, actual)
assert(foo, 'message')
assert(foo, message)
assert(foo, msg)

# bad
class FooTest < Minitest::Test
  def setup
    assert_equal(foo, bar)
  end
end

# good
class FooTest < Minitest::Test
  def test_something
    assert_equal(foo, bar)
  end
end

# bad
class ParentTest < Minitest::Test
  def test_parent # it will run this test twice.
  end
end

class ChildTest < ParentTest
  def test_child
  end
end

# good
class ParentTest < Minitest::Test
  def test_parent
  end
end

class ChildTest < Minitest::Test
  def test_child
  end
end

# good
class ParentTest < Minitest::Test
end

class ChildTest
  def test_child
  end

  def test_parent
  end
end

# bad
do_something
assert_equal(expected, actual)

# good
do_something

assert_equal(expected, actual)

# bad
assert_equal foo, 2
assert_equal foo, [1, 2]
assert_equal foo, [1, 2], 'message'

# good
assert_equal 2, foo
assert_equal [1, 2], foo
assert_equal [1, 2], foo, 'message'

# bad
class FooTest < Minitest::Test
  def test_the_truth
  end
end

# good
class FooTest < Minitest::Test
  def test_the_truth
    assert true
  end
end

# bad
class FooTest
  private # or protected
  def test_does_something
    assert_equal 42, do_something
  end
end

# good
class FooTest
  def test_does_something
    assert_equal 42, do_something
  end
end

# good (not a test case name)
class FooTest
  private # or protected
  def does_something
    assert_equal 42, do_something
  end
end

# good (no assertions)
class FooTest
  private # or protected
  def test_does_something
    do_something
  end
end

# bad
refute(object.empty?)
refute(object.empty?, 'message')

# good
refute_empty(object)
refute_empty(object, 'message')

# bad
assert("rubocop-minitest" != actual)
assert(! "rubocop-minitest" == actual)

# good
refute_equal("rubocop-minitest", actual)

assert_equal(false, nil) # failure
refute(nil)              # success

# bad
assert_equal(false, actual)
assert_equal(false, actual, 'message')

assert(!test)
assert(!test, 'message')

# good
refute(actual)
refute(actual, 'message')

# bad
refute_equal(0.2, actual)
refute_equal(0.2, actual, 'message')

# good
refute_in_delta(0.2, actual)
refute_in_delta(0.2, actual, 0.001, 'message')

# bad
refute(collection.include?(object))
refute(collection.include?(object), 'message')

# good
refute_includes(collection, object)
refute_includes(collection, object, 'message')

# bad
refute(object.instance_of?(Class))
refute(object.instance_of?(Class), 'message')

# good
refute_instance_of(Class, object)
refute_instance_of(Class, object, 'message')

# bad
refute(object.kind_of?(Class))
refute(object.kind_of?(Class), 'message')

# good
refute_kind_of(Class, object)
refute_kind_of(Class, object, 'message')

# bad
refute(matcher.match(string))
refute(matcher.match(string), 'message')

# good
refute_match(matcher, string)
refute_match(matcher, string, 'message')

# bad
refute_equal(nil, actual)
refute_equal(nil, actual, 'message')
refute(actual.nil?)
refute(actual.nil?, 'message')
refute_predicate(object, :nil?)
refute_predicate(object, :nil?, 'message')

# good
refute_nil(actual)
refute_nil(actual, 'message')

# bad
refute(File.exist?(path))
refute(File.exist?(path), 'message')

# good
refute_path_exists(path)
refute_path_exists(path, 'message')

# bad
refute(obj.one?)
refute(obj.one?, 'message')

# good
refute_predicate(obj, :one?)
refute_predicate(obj, :one?, 'message')

# bad
refute(object.respond_to?(:do_something))
refute(object.respond_to?(:do_something), 'message')
refute(respond_to?(:do_something))

# good
refute_respond_to(object, :do_something)
refute_respond_to(object, :do_something, 'message')
refute_respond_to(self, :do_something)

# bad
refute(expected.equal?(actual))

# good
refute_same(expected, actual)

# bad
def test_skip
  skip 'This test is skipped.'

  assert 'foo'.present?
ensure
  do_something
end

# bad
def test_conditional_skip
  skip 'This test is skipped.' if condition

  assert do_something
ensure
  do_teardown
end

# good
def test_skip
  skip 'This test is skipped.'

  begin
    assert 'foo'.present?
  ensure
    do_something
  end
end

# good
def test_conditional_skip
  skip 'This test is skipped.' if condition

  assert do_something
ensure
  if condition
    do_teardown
  end
end

# good
def test_skip_is_used_in_rescue
  do_setup
  assert do_something
rescue
  skip 'This test is skipped.'
ensure
  do_teardown
end

# bad
skip
skip('')

# bad
if condition?
  skip
else
  skip
end

# good
skip("Reason why the test was skipped")

# good
skip if condition?

# bad
my_class.rb

# good
my_class_test.rb
test_my_class.rb

# bad
class FooTest < Minitest::Test
  def does_something
    assert_equal 42, do_something
  end
end

# good
class FooTest < Minitest::Test
  def test_does_something
    assert_equal 42, do_something
  end
end

# good
class FooTest < Minitest::Test
  def helper_method(argument)
  end
end

# bad
assert_raises FooError do
  obj.occur_error
  assert_equal('foo', obj.bar) # Never asserted.
end

# good
assert_raises FooError do
  obj.occur_error
end
assert_equal('foo', obj.bar)

# bad
assert_raises { raise FooException }
assert_raises('This should have raised') { raise FooException }

# good
assert_raises(FooException) { raise FooException }
assert_raises(FooException, 'This should have raised') { raise FooException }

# bad
assert true
assert_equal @foo, @foo
assert_nil [foo, bar]

# good
assert something
assert_equal foo, bar
assert_nil foo
assert false, "My message"