yard server yields 'invalid number of elements (3 for 1..2)'

Question

I am trying to document my Rails application with yard. yardoc produces the desired output in the doc folder. Then I fire up yard server, and I get the message

>> YARD 0.8.7.6 documentation server at http://0.0.0.0:8808
[2014-12-05 17:09:51] INFO  WEBrick 1.3.1
[2014-12-05 17:09:51] INFO  ruby 2.1.2 (2014-05-08) [x86_64-darwin13.0]
[2014-12-05 17:09:51] INFO  WEBrick::HTTPServer#start: pid=70736 port=8808

So far everything as expected.

But as soon as I try to navigate to the given url, I end up with the following error message:

invalid number of elements (3 for 1..2)

Unfortunately, I have no idea what's going on here. I tried to search for the error message, but didn't find a solution. Any help would be appreciated.

Answer 1

Finally, I found the problem :-D

The problem

In your Rails project, you have at least one file that contains a whitespace (in my personal case, I had a copy of a file and the filename was quality_metric copy.rb).

The solution

Remove either the file or the whitespace, run yardoc to force the regeneration of the checksums-file and everything should be fine.

Explanation

The problem appears when Yard tries to load the checksums for the files (the following code snippet is from the file yard/registry_store.rb):

    def load_checksums
      return unless File.file?(checksums_path)
      lines = File.readlines(checksums_path).map do |line|
        line.strip.split(/\s+/)
      end
      @checksums = Hash[lines]
    end

Yard stores the checksums and the according filenames in a file called .yardoc/checksums. When it reads the file in, it reads all lines individually, splits the line by whitespace and stores it into an array (in the codesnippet, that's the lines-variable). In the case of a file containing a whitespace in the name (in particular case, quality_metric copy.rb), then this gets parsed into something like

    ["app/models/quality_metric", "copy.rb", "5034a5e72b3814040aa4bc6881890ab42d72d941"] 

The Hash::[]-method then takes an array of arrays, but assumes that all the subarrays are either of length 1 or 2. When it gets an array of length 3, for instance, it returns the following error message:

ArgumentError: invalid number of elements (3 for 1..2)

So, the error actually has nothing to do with Yard itself, which is why it was so nifty to hunt it down.