How to avoid cyclometic complexity caused by guard blocks? - ruby

Question

I have the following function in one of my classes
def intraday_time_series(opts)
### Guard block ###
valid_resource = opts[:resource] && [:calories, :steps, :distance, :floors, :elevation].include?(opts[:resource])
valid_date = opts[:date]
valid_detail_level = opts[:detailLevel] && %w(1min 15min).include?(opts[:detailLevel])
raise FitgemOauth2::InvalidArgumentError,
'Must specify resource to fetch intraday time series data for.'\
' One of (:calories, :steps, :distance, :floors, or :elevation) is required.' unless valid_resource
raise FitgemOauth2::InvalidArgumentError, 'Must specify the date to fetch intraday time series data for.' unless valid_date
raise FitgemOauth2::InvalidArgumentError,
'Must specify the data resolution to fetch intraday time series data for.'\
' One of (\"1d\" or \"15min\") is required.' unless valid_detail_level
### actual logic ###
resource = opts.delete(:resource)
date = format_date(opts.delete(:date))
detail_level = opts.delete(:detailLevel)
time_window_specified = opts[:startTime] || opts[:endTime]
resource_path = "user/#{#user_id}/activities/"
if time_window_specified
start_time = format_time(opts.delete(:startTime))
end_time = format_time(opts.delete(:endTime))
resource_path += "#{resource}/date/#{date}/1d/#{detail_level}/time/#{start_time}/#{end_time}.json"
else
resource_path += "#{resource}/date/#{date}/1d/#{detail_level}.json"
end
get_call(resource_path)
end
The function has a guard block that checks for any issues with the arguments (the guard block) and if no error is found it does stuff with those arguments.
Now, when I use rubocop to analyze my code, it reports high cyclometic complexity due to the guard blocks. One way I can reduce the complexity is to define another function guard_for_intraday_time_series and move all the guard blocks there. I do not think it as an appropriate solution though because it will populate my code with a guard block for every function that I have in my project.
What is an appropriate way to reduce this complexity, or is it just unavoidable?

Answer 1

You have many intermediate local variables that make the code complicated.
I would refactor it like this:
def intraday_time_series(resource: nil, date: nil,
detailLevel: nil, startTime: nil, endTime: nil)
unless %i[calories steps distance floors elevation].include?(resource)
raise FitgemOauth2::InvalidArgumentError,
"Must specify resource to fetch intraday time series data for."\
" One of (:calories, :steps, :distance, :floors, or :elevation) is required."
end
unless date
raise FitgemOauth2::InvalidArgumentError,
"Must specify the date to fetch intraday time series data for."
end
unless %w(1min 15min).include?(detailLevel)
raise FitgemOauth2::InvalidArgumentError,
"Must specify the data resolution to fetch intraday time series data for."\
" One of (\"1d\" or \"15min\") is required."
end
resource_path = [
"user", #user_id,
"activities", resource,
"date", format_date(date),
"1d", detailLevel
].join("/")
if startTime || endTime
resource_path =
[resource_path, "time", format_time(startTime), format_time(endTime)].join("/")
end
get_call("#{resource_path}.json")
end