rspec users - Jun 2010 - Mocking and specing command line (cli) execution, file operations etc. ?

What are the options for creating specs for file operations, executing
commands in the CLI etc.?

If I build a generator or something which runs a lot of things in the
command line, how do I check the results of these operations, fx
mocking file system updates and/or mocking the STDOUT/STDIN from the
terminal?

There must be some add-on libraries or options for this out there to
make it easy to accomplish.
- Kristian

On Jun 6, 2010, at 7:42 PM, Kristian Mandrup wrote:
> What are the options for creating specs for file operations, executing
> commands in the CLI etc.?
> 
> If I build a generator or something which runs a lot of things in the
> command line, how do I check the results of these operations, fx
> mocking file system updates and/or mocking the STDOUT/STDIN from the
> terminal?
> 
> There must be some add-on libraries or options for this out there to
> make it easy to accomplish.
Check out Fakefs (http://github.com/defunkt/fakefs) for file operations.

There''s a cucumber library called aruba
(http://github.com/aslakhellesoy/aruba) that was extracted from spec suites for
rspec and cucumber specifically to deal with command line applications and their
output. It''s got cucumber step definitions, but there is a separate api
file that has methods you should be able to use to help with this stuff if
you''re using rspec. Or, you could just use cucumber for that stuff as
well.

HTH,
David

Kristian Mandrup wrote:
> What are the options for creating specs for file operations, executing
> commands in the CLI etc.?
>
> If I build a generator or something which runs a lot of things in the
> command line, how do I check the results of these operations, fx
> mocking file system updates and/or mocking the STDOUT/STDIN from the
> terminal?
>
> There must be some add-on libraries or options for this out there to
> make it easy to accomplish.
>   
In addition to aruba if you want to just use RSpec with StringIO objects 
you might find this example group handy:

http://github.com/bmabey/clispec/blob/master/lib/clispec/example_groups/runner.rb

The example group assumes you follow the "runner" pattern where your 
Runner class has a ::run method that takes args, out_stream, 
error_stream.  Many libraries use this pattern including Cucumber and 
RSpec.  The RSpec Book CLI app is setup this way as well if you want to 
see an in-depth example.

In general, for simple CLIs aruba is probably the way to go though.  
This example group is probably best if you want/need to use mocking more 
to avoid expensive operations.

HTH,
Ben