Within MetricFu::Rcov#to_h, it makes the assumption that @global_total_lines_run will always be non-zero, and when it is 0 it causes an exception because you can't divide by zero.

(Not that I ever have 0% coverage mind you :) I found this bug with a misconfiguration of metric_fu that was causing my specs to be skipped. Since it is technically possible for a project to really have 0% coverage I thought I should report this edge case even though it probably won't effect me otherwise)

Is there a way to use MetricFu without using Rake? If not it would be nice if it were made possible.

Im using the newest version. With the default configuration. rake metrics:all failed on
lib/generators/rcov.rb:84 saying NaN

So I poked around in there, division by zero. So I added a small patch
if @global_total_lines != 0 global_percent_run = ((@global_total_lines_run.to_f / @global_total_lines.to_f) * 100) else global_percent_run = 0 end {:rcov => @rcov.merge({:global_percent_run => round_to_tenths(global_percent_run) })}

Thought that would work, but now it throws errors in:

undefined method []' for nil:NilClass /Library/Ruby/Gems/1.8/gems/jscruggs-metric_fu-1.1.5/lib/graphs/rcov_grapher.rb:14:inget_metrics'

Im assuming this is related another issue on this matter. I know other people are having the same issue.