class RuboCop::Cop::Metrics::Utils::AbcSizeCalculator

the formula itself, is easier to test.
We separate the calculator from the cop so that the calculation,
> c2.com/cgi/wiki?AbcMetric<br>> of assignments, branches and conditions for a section of code.
> ABC is .. a software size metric .. computed by counting the number

def self.calculate(node) 

def self.calculate(node)
  new(node).calculate
end

def branch?(node) 

def branch?(node)
  BRANCH_NODES.include?(node.type)
end

def calculate 

def calculate
  @node.each_node do |child|
    if child.assignment?
      @assignment += 1
    elsif branch?(child)
      evaluate_branch_nodes(child)
    elsif condition?(child)
      evaluate_condition_node(child)
    end
  end
  [
    Math.sqrt(@assignment**2 + @branch**2 + @condition**2).round(2),
    "<#{@assignment}, #{@branch}, #{@condition}>"
  ]
end

def condition?(node) 

def condition?(node)
  CONDITION_NODES.include?(node.type)
end

def else_branch?(node) 

def else_branch?(node)
  %i[case if].include?(node.type) &&
    node.else? &&
    node.loc.else.is?('else')
end

def evaluate_branch_nodes(node) 

def evaluate_branch_nodes(node)
  if node.comparison_method?
    @condition += 1
  else
    @branch += 1
  end
end

def evaluate_condition_node(node) 

def evaluate_condition_node(node)
  @condition += 1 if else_branch?(node)
  @condition += 1
end

def initialize(node) 

def initialize(node)
  @assignment = 0
  @branch = 0
  @condition = 0
  @node = node
end