Debugging Sinatra application

3
votes

I install pry and try to use it. 

gem "pry"    

require 'pry'
#..........
binding.pry

But there are 3 issues :

  • I don't know to go to the next string (not to the next break point) or watch the value of a variable. There is no information about it!
  • there is a lot of different prys! pry-debug, pry, pry-db and so on and so forth. Which one should I use?
  • It stops there it should. But I don't know yet (and didn't find) how to watch the variable's value or how to go to the next line. And it always gives in a few seconds a kind of an error below:
pry(#)> Error: execution expired
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:600:in `getbyte'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:600:in `readline'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:600:in `block in readline'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:544:in `handle_read_errors'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:589:in `readline'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:369:in `retrieve_line'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:304:in `block in r'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:301:in `loop'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:301:in `r'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:271:in `re'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:251:in `rep'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:231:in `block (3 levels) in repl'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:230:in `loop'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:230:in `block (2 levels) in repl'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:229:in `catch'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:229:in `block in repl'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:228:in `catch'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_instance.rb:228:in `repl'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/pry_class.rb:154:in `start'
/var/lib/gems/1.9.1/gems/pry-0.9.10/lib/pry/core_extensions.rb:22:in `pry'
/home/alex/Documents/ruby/my_projects/controllers/my_controller.rb:24:in `block in '
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1265:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1265:in `block in compile!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `[]'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `block (3 levels) in route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:851:in `route_eval'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `block (2 levels) in route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:872:in `block in process_route'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:870:in `catch'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:870:in `process_route'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:834:in `block in route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:833:in `each'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:833:in `route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:936:in `dispatch!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:769:in `block in call!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `block in invoke'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `catch'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `invoke'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:769:in `call!'
/home/alex/Documents/ruby/my_projects/app.rb:21:in `block in '
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1265:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1265:in `block in compile!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `[]'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `block (3 levels) in route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:851:in `route_eval'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `block (2 levels) in route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:872:in `block in process_route'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:870:in `catch'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:870:in `process_route'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:834:in `block in route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:833:in `each'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:833:in `route!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:936:in `dispatch!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:769:in `block in call!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `block in invoke'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `catch'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `invoke'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:769:in `call!'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:755:in `call'
/var/lib/gems/1.9.1/gems/rack-flash3-1.0.1/lib/rack/flash.rb:120:in `call'
/var/lib/gems/1.9.1/gems/rack-timeout-0.0.3/lib/rack/timeout.rb:16:in `block in call'
/usr/lib/ruby/1.9.1/timeout.rb:68:in `timeout'
/var/lib/gems/1.9.1/gems/rack-timeout-0.0.3/lib/rack/timeout.rb:16:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/session/abstract/id.rb:205:in `context'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/session/abstract/id.rb:200:in `call'
/var/lib/gems/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in `call'
/var/lib/gems/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/path_traversal.rb:16:in `call'
/var/lib/gems/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/json_csrf.rb:17:in `call'
/var/lib/gems/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:47:in `call'
/var/lib/gems/1.9.1/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/logger.rb:15:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:129:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/head.rb:9:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/methodoverride.rb:21:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/showexceptions.rb:21:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:99:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1389:in `block in call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1471:in `synchronize'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:1389:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/builder.rb:134:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/urlmap.rb:64:in `block in call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/urlmap.rb:49:in `each'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/urlmap.rb:49:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/lint.rb:48:in `_call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/lint.rb:36:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/showexceptions.rb:24:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/commonlogger.rb:20:in `call'
/var/lib/gems/1.9.1/gems/sinatra-1.3.3/lib/sinatra/base.rb:136:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/chunked.rb:43:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/content_length.rb:14:in `call'
/var/lib/gems/1.9.1/gems/rack-1.4.1/lib/rack/handler/webrick.rb:59:in `service'
/usr/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
/usr/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
/usr/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'
pry(#)>

Alright, I install 

gem "debugger"

and add the breakpoint

debugger

Nothing happens at all.

Log file is not what I'm looking for. I just want to debug a Sinatra application. How do I do that?

2
rubydebuggingsinatrarack

2 Answers

6
votes

In your Gemfile:

gem "pry"
gem "pry-nav"

Run bundle. Then whenever the script encounters binding.pry, you will have a shell opened. You can see where you are with whereami, you move to the next line with next, continue running the script with continue. If you want to inspect a variable, just type its name.

See pry-nav for more info.

3
votes

pry-debugger is better. and you need to run sinatra app under Modular style.

I created a repo at github which explains how to use pry to debug.

enter image description here

Here is the repo: https://github.com/hlee/sinatra_debugger_example

Difference between pry-debugger and pry-nav

Pry-debugger

if you check the source code of pry-debugger, you will see:

# pry-debugger.gemspec
# Dependencies
gem.required_ruby_version = '>= 1.9.2'
gem.add_runtime_dependency 'pry', '>= 0.9.10'
gem.add_runtime_dependency 'debugger', '~> 1.3'
gem.add_development_dependency 'pry-remote', '~> 0.1.6'

which means, pry-debugger Only supports MRI 1.9.2 and 1.9.3. Since it reliant on debugger, Pry-debugger will support faster tracing, breakpoints and more.

Pry-nav

on the other hand, here is pry-nav source:

# pry-nav.gemspec
# Dependencies
gem.required_ruby_version = '>= 1.8.7'
gem.add_runtime_dependency 'pry', '~> 0.9.10'
gem.add_development_dependency 'pry-remote', '~> 0.1.6'

which meas, pry-nav is a pure ruby approach not reliant on debugger. will supports 1.8.7, will not supports breakpoints and some other features from debugger.

Breakpoints

break SomeClass#run           # Break at the start of `SomeClass#run`.
break Foo#bar if baz?         # Break at `Foo#bar` only if `baz?`.
break app/models/user.rb:15   # Break at line 15 in user.rb.
break 14                      # Break at line 14 in the current file.

break --condition 4 x > 2     # Change condition on breakpoint #4 to 'x > 2'.
break --condition 3           # Remove the condition on breakpoint #3.

break --delete 5              # Delete breakpoint #5.
break --disable-all           # Disable all breakpoints.

break                         # List all breakpoints. (Same as `breakpoints`)
break --show 2                # Show details about breakpoint #2.

Note

pry-nav and pry-debugger cannot be loaded together.