Example of defensive ruby

defensive-ruby.rb

# example 1: adopting default values and trying to not break things
def adapter(action)
  action = action.to_sym unless action.is_a?(Symbol)
  batch = {
    active_products: "ProductsActive",
    inactive_products: "ProductsInactive",
    download_products: "ProductsDownload"
  }
  batch.fetch(action, "UnknownAction")
end

# example 2: be explicit about your contracts
def adapter(action)
  unless action.is_a?(Symbol)
    raise ArgumentError, "action parameter must be a symbol. Action: #{action.to_s}"
  end
  batch = {
    active_products: "ProductsActive",
    inactive_products: "ProductsInactive",
    download_products: "ProductsDownload"
  }
  batch.fetch(action) do |value|
    raise ArgumentError, "Unexpected value for action: #{value}"
  end
end

https://medium.com/@rogerleite/%C3%B3timas-dicas-jessica-chaves-%C3%B3timo-post-b38367c1898a