Ignore UnusedBlockArgument for keyword arguments #2314

volkert · 2015-10-09T13:38:59Z

This PR is related to #2304 with a fix for unused block arguments.

Rubocop currently suggests to prepend an underscore to unused keyword arguments for blocks. This would break the keyword argument and theres no other way around it but ignoring the fact that there are unused keyword arguments.

bbatsov · 2015-10-10T14:34:40Z

Apart from the failing build, the change looks reasonable to me.

bbatsov · 2015-10-10T14:35:12Z

spec/rubocop/cop/lint/unused_block_argument_spec.rb

+    context 'when a keyword argument is not used' do
+      let(:source) { <<-END }
+        1.times do |foo:|
+          puts 'foo'


Something like define_method is the only reasonable use of keyword arguments with blocks I can think of, so it would be a better example here.

volkert · 2015-10-12T08:10:35Z

The build still fails for ruby 1.9.3 because it's unable to parse code with keyword arguments successfully. Any good ideas on how to work around that? I could return from the test early if RUBY_VERSION < '2.0.0'

maxjacobson · 2015-10-12T16:26:48Z

@volkert you can reference the circular argument reference spec https://github.com/bbatsov/rubocop/blob/aa7d73992fcd1abbf3b57e56e6d9888a8e45d682/spec/rubocop/cop/lint/circular_argument_reference_spec.rb#L23

volkert · 2015-10-13T08:33:25Z

@maxjacobson thanks! The build now passes for all versions.

bbatsov · 2015-10-15T20:11:01Z

Btw, is the real issue the reporting or the suggested correction? I think it's worth reporting those by default, unless someone opts it's not (meaning this should probably be a config option).

bbatsov · 2015-10-23T06:19:40Z

@volkert ping

volkert · 2015-11-03T13:49:12Z

spec/rubocop/cop/lint/unused_block_argument_spec.rb

+        expect(cop.highlights).to eq(['bar'])
+        expect(cop.offenses.first.message).to eq(
+          'Unused block argument - `bar`. ' \
+          "You can omit the argument if you don't care about it."


Sorry for the late response! I made it configurable through AllowUnusedKeywordArguments now. I'm not sure about the error message here, though. It' actually not true that the argument can be omitted. If it is omitted ruby will complain about an unknown keyword. What do you think?

If the user controls both the caller and callee, they can remove an unneeded keyword arg on both sides. If they only control the callee, then that is a problem.

Well, this message didn't really take keyword args into account. Maybe it should be different for them?

volkert · 2015-11-12T15:22:42Z

@bbatsov Anything left to improve here? I'd be happy to help bringing this one to master!

bbatsov · 2015-11-13T06:12:32Z

Btw, is the real issue the reporting or the suggested correction? I think it's worth reporting those by default, unless someone opts it's not (meaning this should probably be a config option).

You never replied to this comment of mine.

volkert · 2015-11-13T14:43:41Z

Actually both. The suggested correction broke the code and I'm not sure how useful it is to report unused keywords, especially if the only way of fixing it is adding an option to ignore keywords. There is no good way of improving your code to prevent the violation. But I'd be fine with how it is right now.

volkert · 2015-12-10T12:24:58Z

@bbatsov so, how do we proceed with this?

bbatsov · 2015-12-10T12:42:23Z

I'm still not sure what exactly is this change supposed to fix. Some real examples would help.

volkert · 2015-12-10T16:20:07Z

I have a test which expects a method to be called with keyword arguments that I want to run an expect on:

expect(Foo).to receive(:bar) do |one_param:, another_object:|
  expect(another_object.bar).to eql(0)
end

(similar to my real code)

If I run rubocop on this, it complains that:

Unused block argument - one_param. If it's necessary, use _ or _one_param as an argument name to indicate that it won't be used.
    expect(Foo).to receive(:bar) do |one_param:, another_object:|

The problem with the renaming is that it is a keyword argument, so the name matters here. If I replace it with an underscore or prefix it, rubocop is happy but ruby is sad because of a missing keyword.

ArgumentError: missing keyword: _one_param

So it's either ruby or rubocop complaining, there is no way of making both happy.

My first approach for the PR to fix this was to not check for unused keywords at all because I cannot think of a situation where one is able to rename the keyword. But since you preferred having an opt-out for this, I changed my PR. This is similar to #2304.

Sorry for causing so much confustion. I hope I managed to explain my situation and we can bring this to master soon ;)
Let me know if I can help in any way!

volkert · 2016-01-22T15:04:53Z

@bbatsov any updates on this?

bbatsov · 2016-02-03T14:18:48Z

Sorry for the late response - too much things to do... I see your point now. Rebase this and I'll accept it.

volkert · 2016-03-30T08:31:29Z

@bbatsov I rebased it and it should be fine to merge it now. I had to do some minor changes for the tests/rubocop to pass.

bbatsov · 2016-03-30T09:09:28Z

CHANGELOG.md

@@ -420,6 +420,7 @@
 * [#2393](https://github.com/bbatsov/rubocop/pull/2393): `Style/MethodCallParentheses` doesn't fail on `obj.method ||= func()`. ([@alexdowad][])
 * [#2344](https://github.com/bbatsov/rubocop/pull/2344): When autocorrecting, `Style/ParallelAssignment` reorders assignment statements, if necessary, to avoid breaking code. ([@alexdowad][])
 * `Style/MultilineOperationAlignment` does not try to align the receiver and selector of a method call if both are on the LHS of an assignment. ([@alexdowad][])
+* [#2314](https://github.com/bbatsov/rubocop/pull/2314): Ignore `UnusedBlockArgument` for keyword arguments. ([@volkert][])


You'll have to move this to the master section.

bbatsov · 2016-03-30T09:10:06Z

@volkert Just address my note about the outdated position of the changelog entry.

volkert · 2016-03-30T11:44:18Z

Done!

bbatsov · 2016-03-30T11:45:55Z

CHANGELOG.md

@@ -1,6 +1,7 @@
 # Change log

 ## master (unreleased)
+* [#2314](https://github.com/bbatsov/rubocop/pull/2314): Ignore `UnusedBlockArgument` for keyword arguments. ([@volkert][])


This should be 3 lines down under bug fixes I guess.

bbatsov · 2016-03-30T15:56:58Z

👍 Great success!

volkert force-pushed the unused_block_keyword_argument branch 2 times, most recently from 85d4b0f to 86ae301 Compare October 9, 2015 13:51

bbatsov reviewed Oct 10, 2015
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volkert force-pushed the unused_block_keyword_argument branch 2 times, most recently from e1aeb97 to b83fbc2 Compare October 12, 2015 07:58

volkert force-pushed the unused_block_keyword_argument branch from b83fbc2 to 627912c Compare October 13, 2015 08:15

volkert force-pushed the unused_block_keyword_argument branch 2 times, most recently from d83a571 to 6b3940d Compare November 3, 2015 13:45

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volkert force-pushed the unused_block_keyword_argument branch from 6b3940d to 7698a4c Compare December 10, 2015 16:27

volkert force-pushed the unused_block_keyword_argument branch 6 times, most recently from b071412 to fc7aad3 Compare March 29, 2016 15:58

bbatsov reviewed Mar 30, 2016
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volkert force-pushed the unused_block_keyword_argument branch from fc7aad3 to 96125dd Compare March 30, 2016 11:43

bbatsov reviewed Mar 30, 2016
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Ignore unused block parameter if it is a keyword argument

8f01fbe

volkert force-pushed the unused_block_keyword_argument branch from 96125dd to 8f01fbe Compare March 30, 2016 11:49

bbatsov merged commit 7e2ee32 into rubocop:master Mar 30, 2016

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Ignore UnusedBlockArgument for keyword arguments #2314

Ignore UnusedBlockArgument for keyword arguments #2314

volkert commented Oct 9, 2015

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Ignore UnusedBlockArgument for keyword arguments #2314

Ignore UnusedBlockArgument for keyword arguments #2314

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