Error installing gems

Question

I am getting an error when installing certain gems. I am using ubuntu 10.10. The error messages shows this.

ERROR:  While executing gem ... (NoMethodError)
undefined method `spec' for nil:NilClass

Answer 1

Some gems rely on other gems to run, but haven't been setup correctly to automatically install them (ie they haven't had their dependencies correctly set).

You'll often only find out when you try to run them... just like this.

luckily the error message here makes it fairly clear that you need the "rspec" gem installed... and as you've already discovered, the solution is simply to install the missing gem.

Other gems aren't often as easy to figure out, but googling for the error message (or putting it up on StackOverflow) usually sorts it out pretty quick.