[Fix #1682] Add STDIN support

[caseywebdev]

Without STDIN support, text editor plugins have to create tmp files to implement lint-as-you-type because the actual file is not saved yet. This is far from ideal, and this PR aims to fix that. Here's example usage:

$ echo '{:foo => :bar}' | bin/rubocop -s the-file-path.rb
Inspecting 1 file
C

Offenses:

the-file-path.rb:1:1: C: Missing utf-8 encoding comment.
{:foo => :bar}
^
the-file-path.rb:1:1: C: Use snake_case for source file names.
{:foo => :bar}
^
the-file-path.rb:1:1: C: Space inside { missing.
{:foo => :bar}
^
the-file-path.rb:1:2: C: Use the new Ruby 1.9 hash syntax.
{:foo => :bar}
 ^^^^^^^
the-file-path.rb:1:14: C: Space inside } missing.
{:foo => :bar}
             ^

1 file inspected, 5 offenses detected

The file path is still used for things like source file name linting, but the raw source comes from STDIN.

[steelbrain]

@caseywebdev does rubocop search for any rc files? 'cause if it does, You might have to add an extra parameter like --stdin-filepath referring to the path of the stdin input so it can resolve the imports/rc files.

[caseywebdev]

@steelbrain The path is passed just the same as it always is, as the last command line argument. The -s/--stdin flag just tells the runner to ignore the contents of the file and use the content of STDIN.

See the example above.

[steelbrain]

Although this is not my repo, but it would be nice if you would add some tests to it.

[caseywebdev]

I would, but the rspec DSL makes me crazy.

[tfausak]

👍

[jonas054]

@caseywebdev I think you should add validation for the new option, checking that exactly one file argument is given. And you need to add testing. Even if you're not used to RSpec.

[caseywebdev]

@jonas054 I've added tests

[jonas054]

The code looks good to me. You just need to add the option to the Command flag table on the README page. Mention that it's useful for editor integration.

[caseywebdev]

Added -s/--stdin to the command flag table with a note about editor integration.

[jonas054]

👍 I'm satisfied. We'll see if @bbatsov has more comments.

[bbatsov]

Apart from the failing build - the code looks good to me.

[caseywebdev]

Whoops, forgot to update the help output spec. It should pass this time.

[bbatsov]

Where do you pass args to the runner?

[bbatsov]

I'd also like to ask you to change the commit message's title to [Fix #1682] Add STDIN support. You can mention the AtomLinter ticket and some extra explanations in the commit's body.

[caseywebdev]

Done

[bbatsov]

One more thing I noticed too late - you need to add a changelog entry.

[caseywebdev]

Done

[bbatsov]

And the build failed again.

[caseywebdev]

Whoops, my bad. Should work now.

[bbatsov]

This has to be rebased on top of the current master.

[caseywebdev]

Done

[caseywebdev]

🎆