[bot] Fix Rails/Blank by 6[bot] · Pull Request #206 · 6/nitrocop

6 · 2026-03-26T01:24:44Z

Status: Agent is working on this fix...

Cop: Rails/Blank | Backend: claude / hard | Model: Claude Opus 4.6 (high) | Mode: fix
Code bugs: 9 | Run: https://github.com/6/nitrocop/actions/runs/23572694990

Refs #160

Task prompt (4398 tokens)

Fix Rails/Blank — 0 FP, 14 FN

Instructions

You are fixing ONE cop in nitrocop, a Rust Ruby linter that uses Prism for parsing.

Current state: 6,472 matches, 0 false positives, 14 false negatives.
Focus on: FN (RuboCop flags code nitrocop misses).

⚠ 6,472 existing matches must not regress. Validate with check_cop.py before committing.

Workflow

Read the Pre-diagnostic Results and Corpus FP/FN Examples sections below first
Verify with RuboCop first (for FP fixes): before writing any code, confirm RuboCop's
behavior on BOTH the specific FP case AND the general pattern:
```
echo '<specific FP case>' > /tmp/test.rb && rubocop --only Rails/Blank /tmp/test.rb
echo '<general pattern>' > /tmp/test.rb && rubocop --only Rails/Blank /tmp/test.rb
```
If RuboCop flags the general pattern, your fix must be narrow enough to not suppress it.
Add a test case FIRST:
- FN fix: add the missed pattern to tests/fixtures/cops/rails/blank/offense.rb with ^ annotation
- FP fix: add the false-positive pattern to tests/fixtures/cops/rails/blank/no_offense.rb
Verify test fails: cargo test --lib -- cop::rails::blank
Fix src/cop/rails/blank.rs
Verify test passes: cargo test --lib -- cop::rails::blank
Validate against corpus (REQUIRED before committing):
```
python3 scripts/check_cop.py Rails/Blank --rerun --clone --sample 15
```
If this reports FP or FN regression, your fix is too broad — narrow it down.
Add a /// doc comment on the cop struct documenting what you found and fixed
Commit only your cop's files

Fixture Format

Mark offenses with ^ markers on the line AFTER the offending source line.
The ^ characters must align with the offending columns. The message format is Rails/Blank: <message text>.
See the Current Fixture sections below for real examples from this cop.

If your test passes immediately

If you add a test case and it passes without code changes, the corpus mismatch is
caused by config/context differences, not a detection bug.
Do NOT loop trying to make the test fail. Instead:

Investigate config resolution (Include/Exclude, cop enablement, disable comments)
The fix is likely in src/config/ or the cop's config handling, not detection logic
If you cannot determine the root cause within 5 minutes, document your findings as
a /// comment on the cop struct and commit

CRITICAL: Avoid regressions in the opposite direction

When fixing FPs, your change MUST NOT suppress legitimate detections. When fixing FNs,
your change MUST NOT flag code that RuboCop accepts. A fix that eliminates a few issues
in one direction but introduces hundreds in the other is a catastrophic regression.

Before exempting a category of patterns, verify with RuboCop that the general case
is still an offense:

rubocop --only Rails/Blank /tmp/test.rb

If RuboCop flags the general pattern but not your specific case, the difference is in
a narrow context (e.g., enclosing structure, receiver type, argument count) — your fix
must target that specific context, not the broad category.

Rule of thumb: if your fix adds an early return or continue that skips a whole
node type, operator class, or naming pattern, it's probably too broad. Prefer adding a
condition that matches the SPECIFIC differentiating context.

Rules

Only modify src/cop/rails/blank.rs and tests/fixtures/cops/rails/blank/
Run cargo test --lib -- cop::rails::blank to verify your fix (do NOT run the full test suite)
Run python3 scripts/check_cop.py Rails/Blank --rerun --clone --sample 15 before committing to catch regressions
Do NOT touch unrelated files
Do NOT use git stash

Current Fixture: offense.rb

tests/fixtures/cops/rails/blank/offense.rb

!x.present?
^^^^^^^^^^^ Rails/Blank: Use `blank?` instead of `!present?`.

!name.present?
^^^^^^^^^^^^^^ Rails/Blank: Use `blank?` instead of `!present?`.

!user.email.present?
^^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `blank?` instead of `!present?`.

x.nil? || x.empty?
^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `x.blank?` instead of `x.nil? || x.empty?`.

name.nil? || name.empty?
^^^^^^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `name.blank?` instead of `name.nil? || name.empty?`.

foo == nil || foo.empty?
^^^^^^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `foo.blank?` instead of `foo == nil || foo.empty?`.

something unless foo.present?
          ^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `if foo.blank?` instead of `unless foo.present?`.

something unless present?
          ^^^^^^^^^^^^^^^ Rails/Blank: Use `if blank?` instead of `unless present?`.

unless foo.present?
^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `if foo.blank?` instead of `unless foo.present?`.
  something
end

!foo || foo.empty?
^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `foo.blank?` instead of `!foo || foo.empty?`.

!methods || methods.empty?
^^^^^^^^^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `methods.blank?` instead of `!methods || methods.empty?`.

!url || url.empty?
^^^^^^^^^^^^^^^^^^ Rails/Blank: Use `url.blank?` instead of `!url || url.empty?`.

return self if nil? || empty?
               ^^^^^^^^^^^^^^ Rails/Blank: Use `blank?` instead of `nil? || empty?`.
return [] if nil? || empty?
             ^^^^^^^^^^^^^^ Rails/Blank: Use `blank?` instead of `nil? || empty?`.

Current Fixture: no_offense.rb

tests/fixtures/cops/rails/blank/no_offense.rb

x.blank?
x.present?
!x.empty?
x.nil?
name.present? && name.length > 0
x.nil? || y.empty?
x.nil? && x.empty?
x.nil? || x.zero?
something if foo.present?
something unless foo.blank?
def blank?
  !present?
end
unless foo.present?
  something
else
  something_else
end

# present? called with argument (class method style) should NOT be flagged
# RuboCop's NodePattern `(send (send $_ :present?) :!)` requires present? with no arguments
!Helpers.present?(value)
!Vagrant::Util::Presence.present?(directory)
unless Helpers.present?(value)
  do_something
end

# safe navigation on present?/empty? — RuboCop's NodePattern matches send not csend
# so &.present? and &.empty? should NOT be flagged
return [] unless response&.strip&.present?
unless object&.present?
  do_something
end
foo.nil? || foo&.empty?

# pattern match guard: `in pattern unless condition` is not a regular unless
# RuboCop's on_if handler does not visit pattern match guards
case element.name
in "div" unless element.at("div").present?
  element.name = "p"
end

# safe navigation with !present? — semantics differ:
# !pkey_cols&.present? when pkey_cols is nil → !nil → true
# pkey_cols&.blank? when pkey_cols is nil → nil (falsy)
# RuboCop skips this pattern because `(send (send $_ :present?) :!)` doesn't
# match csend (safe navigation).
id_option = if pk_is_also_fk || !pkey_cols&.present?

Key Source Files

Rust implementation: src/cop/rails/blank.rs
RuboCop Ruby source (ground truth): vendor/rubocop-rails/lib/rubocop/cop/rails/blank.rb
RuboCop test excerpts: vendor/rubocop-rails/spec/rubocop/cop/rails/blank_spec.rb

Read these files before making changes.

Start Here

Use the existing corpus data to focus on the most concentrated regressions first.

Helpful local commands:

python3 scripts/investigate_cop.py Rails/Blank --repos-only
python3 scripts/investigate_cop.py Rails/Blank --context
python3 scripts/verify_cop_locations.py Rails/Blank

Top FN repos:

databasically__lowdown__d593927 (5 FN) — example vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:594
cjstewart88__Tubalr__f6956c8 (4 FN) — example heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/parser/c.rb:784
pitluga__supply_drop__d64c50c (4 FN) — example examples/vendored-puppet/vendor/puppet-2.7.8/lib/puppet/util/adsi.rb:161

Representative FN examples:

cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/parser/c.rb:784 — Use elements.blank? instead of elements.nil? or elements.empty?.
cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/ri/driver.rb:865 — Use name.blank? instead of name.nil? or name.empty?.
cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/parser/c.rb:782 — Use elements.blank? instead of elements.nil? or elements.empty?.

Pre-diagnostic Results

Diagnosis Summary

Each example was tested by running nitrocop on the extracted source in isolation
with --force-default-config to determine if the issue is a code bug or config issue.
Note: source context is truncated and may not parse perfectly. If a diagnosis
seems wrong (e.g., your test passes immediately for a 'CODE BUG'), treat it as
a config/context issue instead.

FN: 14 code bug(s), 0 config/context issue(s)

FN #1: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/parser/c.rb:784`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Enclosing structure: if branch (line: if type.downcase == 'const' then)
The offense is inside this structure — the cop may need
to handle this context to detect the pattern.

Message: Use elements.blank?instead ofelements.nil? or elements.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

      if elements.nil? or elements.empty? then
^ Rails/Blank: Use `elements.blank?` instead of `elements.nil? or elements.empty?`.

Full source context:

    # In the case of rb_define_const, the definition and comment are in
    # "/* definition: comment */" form.  The literal ':' and '\' characters
    # can be escaped with a backslash.
    if type.downcase == 'const' then
      elements = comment.split ':'

      if elements.nil? or elements.empty? then
        con = RDoc::Constant.new const_name, definition, comment
      else
        new_definition = elements[0..-2].join(':')

        if new_definition.empty? then # Default to literal C definition
          new_definition = definition
        else

FN #2: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/ri/driver.rb:865`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Message: Use name.blank?instead ofname.nil? or name.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

      return if name.nil? or name.empty?
^ Rails/Blank: Use `name.blank?` instead of `name.nil? or name.empty?`.

Full source context:

      name = if defined? Readline then
               Readline.readline ">> "
             else
               print ">> "
               $stdin.gets
             end

      return if name.nil? or name.empty?

      name = expand_name name.strip

      begin
        display_name name
      rescue NotFoundError => e
        puts e.message

FN #3: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/parser/c.rb:782`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Enclosing structure: if branch (line: if type.downcase == 'const' then)
The offense is inside this structure — the cop may need
to handle this context to detect the pattern.

Message: Use elements.blank?instead ofelements.nil? or elements.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

      if elements.nil? or elements.empty? then
^ Rails/Blank: Use `elements.blank?` instead of `elements.nil? or elements.empty?`.

Full source context:

    # In the case of rb_define_const, the definition and comment are in
    # "/* definition: comment */" form.  The literal ':' and '\' characters
    # can be escaped with a backslash.
    if type.downcase == 'const' then
      elements = comment.split ':'

      if elements.nil? or elements.empty? then
        con = RDoc::Constant.new const_name, definition, comment
      else
        new_definition = elements[0..-2].join(':')

        if new_definition.empty? then # Default to literal C definition
          new_definition = definition
        else

FN #4: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/ri/driver.rb:878`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Message: Use name.blank?instead ofname.nil? or name.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

      return if name.nil? or name.empty?
^ Rails/Blank: Use `name.blank?` instead of `name.nil? or name.empty?`.

Full source context:

      name = if defined? Readline then
               Readline.readline ">> "
             else
               print ">> "
               $stdin.gets
             end

      return if name.nil? or name.empty?

      name = expand_name name.strip

      begin
        display_name name
      rescue NotFoundError => e
        puts e.message

FN #5: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:594`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Enclosing structure: method body (line: def __format(to_wrap) #:nodoc:)
The offense is inside this structure — the cop may need
to handle this context to detect the pattern.

Message: Use words[0].blank?instead ofwords[0].nil? or words[0].empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

      words.shift if words[0].nil? or words[0].empty?
^ Rails/Blank: Use `words[0].blank?` instead of `words[0].nil? or words[0].empty?`.

Full source context:

  private
    def __do_split_word(word, size) #:nodoc:
      [word[0 .. (size - 1)], word[size .. -1]]
    end

    def __format(to_wrap) #:nodoc:
      words = to_wrap.split(/\s+/).compact
      words.shift if words[0].nil? or words[0].empty?
      to_wrap = []

      abbrev = false
      width = @columns - @first_indent - @left_margin - @right_margin
      indent_str = ' ' * @first_indent
      first_line = true
      line = words.shift

FN #6: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:602`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Message: Use line.blank?instead ofline.nil? || line.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

      abbrev = __is_abbrev(line) unless line.nil? || line.empty?
^ Rails/Blank: Use `line.blank?` instead of `line.nil? || line.empty?`.

Full source context:

      to_wrap = []

      abbrev = false
      width = @columns - @first_indent - @left_margin - @right_margin
      indent_str = ' ' * @first_indent
      first_line = true
      line = words.shift
      abbrev = __is_abbrev(line) unless line.nil? || line.empty?

      while w = words.shift
        if (w.size + line.size < (width - 1)) ||
           ((line !~ LEQ_RE || abbrev) && (w.size + line.size < width))
          line << " " if (line =~ LEQ_RE) && (not abbrev)
          line << " #{w}"
        else

FN #7: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:630`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Enclosing structure: block (do..end) (line: loop do)
The offense is inside this structure — the cop may need
to handle this context to detect the pattern.

Message: Use line.blank?instead ofline.nil? or line.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

        break if line.nil? or line.empty?
^ Rails/Blank: Use `line.blank?` instead of `line.nil? or line.empty?`.

Full source context:

          line = w
        end

        abbrev = __is_abbrev(w) unless w.nil?
      end

      loop do
        break if line.nil? or line.empty?
        line, w = __do_hyphenate(line, w, width) if @hard_margins
        to_wrap << __make_line(line, indent_str, width, w.nil?)
        line = w
      end

      if (@tag_paragraph && (to_wrap.size > 0)) then
        clr = %r{`(\w+)'}.match([caller(1)].flatten[0])[1]

FN #8: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:790`

NOT DETECTED — CODE BUG
The cop fails to detect this pattern. Fix the detection logic.

Enclosing structure: enclosing line: else
The offense is inside this structure — the cop may need
to handle this context to detect the pattern.

Message: Use rnext.blank?instead ofrnext.nil? or rnext.empty?.

Ready-made test snippet (add to offense.rb, adjust ^ count):

          break if rnext.nil? or rnext.empty? or rline.nil? or rline.empty?
^ Rails/Blank: Use `rnext.blank?` instead of `rnext.nil? or rnext.empty?`.

Full source context:

            words[-1] = first
            @split_words << SplitWord.new(word, first, rest)
          end
          rline = words.join(' ').strip
          rnext = "#{rest} #{rnext}".strip
          break
        else
          break if rnext.nil? or rnext.empty? or rline.nil? or rline.empty?
          words = rnext.split(/\s+/)
          word = words.shift
          size = width - rline.size - 1

          if (size <= 0)
            rnext = "#{word} #{words.join(' ')}".strip
            break

Omitted 6 additional diagnosed FN example(s) for brevity.

6 · 2026-03-26T01:27:28Z

Agent failed. See run: https://github.com/6/nitrocop/actions/runs/23572694990

[bot] Fix Rails/Blank: in progress

0d4b516

6 bot added type:cop-fix model:claude-hard labels Mar 26, 2026

6 bot closed this Mar 26, 2026

6 bot deleted the fix/rails-blank-23572694990 branch March 26, 2026 01:27

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[bot] Fix Rails/Blank#206

[bot] Fix Rails/Blank#206
6[bot] wants to merge 1 commit intomainfrom
fix/rails-blank-23572694990

6 bot commented Mar 26, 2026 •

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6 bot commented Mar 26, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Fix Rails/Blank — 0 FP, 14 FN

Instructions

Workflow

Fixture Format

If your test passes immediately

CRITICAL: Avoid regressions in the opposite direction

Rules

Current Fixture: offense.rb

Current Fixture: no_offense.rb

Key Source Files

Start Here

Pre-diagnostic Results

Diagnosis Summary

FN #1: cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/parser/c.rb:784

FN #2: cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/ri/driver.rb:865

FN #3: cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/parser/c.rb:782

FN #4: cjstewart88__Tubalr__f6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/ri/driver.rb:878

FN #5: databasically__lowdown__d593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:594

FN #6: databasically__lowdown__d593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:602

FN #7: databasically__lowdown__d593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:630

FN #8: databasically__lowdown__d593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:790

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FN #1: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/parser/c.rb:784`

FN #2: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.8/lib/rdoc/ri/driver.rb:865`

FN #3: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/parser/c.rb:782`

FN #4: `cjstewart88Tubalrf6956c8: heroku/ruby/1.9.1/gems/rdoc-3.9.4/lib/rdoc/ri/driver.rb:878`

FN #5: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:594`

FN #6: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:602`

FN #7: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:630`

FN #8: `databasicallylowdownd593927: vendor/rails/actionmailer/lib/action_mailer/vendor/text-format-0.6.3/text/format.rb:790`