How do I get ruby to print a full backtrace instead of a truncated one?

Question

When I get exceptions, it is often from deep within the call stack. When this happens, more often than not, the actual offending line of code is hidden from me:

tmp.rb:7:in `t': undefined method `bar' for nil:NilClass (NoMethodError)
        from tmp.rb:10:in `s'
        from tmp.rb:13:in `r'
        from tmp.rb:16:in `q'
        from tmp.rb:19:in `p'
        from tmp.rb:22:in `o'
        from tmp.rb:25:in `n'
        from tmp.rb:28:in `m'
        from tmp.rb:31:in `l'
         ... 8 levels...
        from tmp.rb:58:in `c'
        from tmp.rb:61:in `b'
        from tmp.rb:64:in `a'
        from tmp.rb:67

That "... 8 levels..." truncation is causing me a great deal of trouble. I'm not having much success googling for this one: How do I tell ruby that I want dumps to include the full stack?

Answer 1

Exception#backtrace has the entire stack in it:

def do_division_by_zero; 5 / 0; end
begin
  do_division_by_zero
rescue => exception
  puts exception.backtrace
end

(Taken from Peter Cooper's Ruby Inside blog)

Answer 2

IRB has a setting for this awful "feature", which you can customize.

Create a file called ~/.irbrc that includes the following line:

IRB.conf[:BACK_TRACE_LIMIT] = 100

This will allow you to see 100 stack frames in irb, at least. I haven't been able to find an equivalent setting for the non-interactive runtime.

Detailed information about IRB customization can be found in the Pickaxe book.

Answer 3

I was getting these errors when trying to load my test environment (via rake test or autotest) and the IRB suggestions didn't help. I ended up wrapping my entire test/test_helper.rb in a begin/rescue block and that fixed things up.

begin
  class ActiveSupport::TestCase
    #awesome stuff
  end
rescue => e
  puts e.backtrace
end