assert{ 2.0 }

Railsers:

The following RubyUnit assertions are now obsolete:

  assert
  assert_block
  assert_equal
  assert_instance_of
  assert_kind_of
  assert_operator
  assert_match
  assert_nil
  assert_no_match
  assert_not_equal
  assert_not_nil

The next time you think to type any of them, use assert{ 2.0 } instead.
Put whatever you like inside the { block }. assert_equal(x, y) becomes
assert{ x == y }. assert_not_nil(x) becomes ... just assert{ x }! If the
last statement in that block fails, your test runner will reflect the
name and value of every variable in your assertion. Diagnosing assertion
failures has never been easier!

Get assert{ 2.0 } the usual way:

  gem install assert2

Then require 'assert2' into your test suites.

Use deny{} for situations like assert_nil that must fail.

To provide even more commentary, when either assertion fails, pass a
string into either assert or deny, like this:

  assert('my colleague made me do this'){ foo() < 42 }

Note: This works "best" with Ruby 1.8.6!

Feedback welcome, and happy testing!