```ruby
module Test::Unit
 
  class TestCase
   
    def self.must(name, &block)
      test_name = "test_#{name.gsub(/\s+/,'_')}".to_sym
      defined = instance_method(test_name) rescue false
      raise "#{test_name} is already defined in #{self}" if defined
      if block_given?
        define_method(test_name, &block)
      else
        define_method(test_name) do
          flunk "No implementation provided for #{name}"
        end
      end
    end
 
  end
end


module Test::Unit::Assertions
  def assert_false(object, message="")
    assert_equal(false, object, message)
  end
  def assert_true(object, message="")
    assert_equal(true, object, message)
  end
end

```

Add assert_nil extension to Test::Unit.
user
```ruby
module Test::Unit
 
  class TestCase
   
    def self.must(name, &block)
      test_name = "test_#{name.gsub(/\s+/,'_')}".to_sym
      defined = instance_method(test_name) rescue false
      raise "#{test_name} is already defined in #{self}" if defined
      if block_given?
        define_method(test_name, &block)
      else
        define_method(test_name) do
          flunk "No implementation provided for #{name}"
        end
      end
    end
 
  end
end


module Test::Unit::Assertions
  def assert_false(object, message="")
    assert_equal(false, object, message)
  end
  def assert_true(object, message="")
    assert_equal(true, object, message)
  end
  def assert_nil(object, message="")
    assert_equal(nil, object, message)
  end
end

```
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