Module: BetterAssertDifference

Defined in:
lib/better_assert_difference.rb,
lib/better_assert_difference/version.rb

Constant Summary collapse

DEFAULT_DIFF =
1
VERSION =
'0.1.3'

Instance Method Summary collapse

Instance Method Details

#assert_difference(expression, difference = DEFAULT_DIFF, message = nil, &block) ⇒ Object



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# File 'lib/better_assert_difference.rb', line 6

def assert_difference(expression, difference = DEFAULT_DIFF, message = nil, &block)
  expression_to_diff =
    if expression.is_a?(Hash)
      expression
    else
      Array(expression).each_with_object({}) { |exp, expression_hash| expression_hash[exp] = DEFAULT_DIFF }
    end
  block_to_diff =
    expression_to_diff.each_with_object({}) do |(exp, diff), expression_hash|
      key =
        if exp.respond_to?(:call)
          exp
        elsif exp.respond_to?(:count) && !exp.is_a?(String)
          -> { exp.count }
        else
          -> { eval(exp, block.binding) }
        end
      expression_hash[key] = diff
    end
  before = block_to_diff.keys.map(&:call)
  retval = yield
  block_to_diff.each_with_index do |(exp, diff), i|
    error  = "#{exp.inspect} didn't change by #{diff}"
    error  = "#{message}.\n#{error}" if message
    assert_equal(before[i] + diff, exp.call, error)
  end
  retval
end