Sweep two thirds of the rubocop directives out of the code

63 rubocop:disable and enable markers become 22, all three ways.

Whole-file judgments move into .rubocop.yml, justification and all:
the Metrics exemptions for the one-concern homes (Production,
CoverageViolations, the usage document, the location conventions, the
viewer-data validator, the sandbox harness, the dogfood report), the
Naming/PredicateMethod allowance for commands that report whether
they acted, the class-variable fakes that mirror Minitest's own flag,
and the behavior-describing specs no single class owns. Fixtures are
now excluded wholesale as the byte-stable inputs they are, which
retires their inline markers and the per-fixture exclusion list. The
two directive lines inside fixtures become plain comments rather than
disappearing, so the line numbers the specs assert against stay put.

Two sites are refactored instead: the RSpec stand-ins in the test
tracker spec become verified class and instance doubles, and the
shadowing inspect's unused parameter gains its underscore.

What remains inline is the deliberate minimum, each with its reason:
Marshal on our own pipes, stderr that must not be warn, the literal
/dev/null of a git diff, evals whose foreign location is the point,
and their kin.

Author: sferik

.rubocop.yml

@@ -5,12 +5,10 @@ plugins:
 
 AllCops:
   Exclude:
-    - "spec/fixtures/iso-8859.rb"
-    - "spec/fixtures/utf-8.rb"
-    - "spec/fixtures/utf-8-magic.rb"
-    - "spec/fixtures/euc-jp.rb"
-    - "spec/fixtures/empty_euc-jp.rb"
-    - "spec/fixtures/euc-jp-shebang.rb"
+    # Fixtures are byte-stable test inputs: their line numbers, layout,
+    # and sometimes their encodings are what the specs assert against,
+    # so they are not subject to style.
+    - "spec/fixtures/**/*"
     - "test_projects/**/*"
     - "tmp/**/*"
     - "vendor/bundle/**/*"
@@ -51,6 +49,37 @@ Metrics/ModuleLength:
     # One settings module per concern; the explicit writers beside each
     # dual-purpose reader push this one just past the default.
     - "lib/simplecov/configuration/merging.rb"
+    # One cohesive runtime state machine, kept in one place for the same
+    # reason a state machine is not split across files by size alone.
+    - "lib/simplecov/production.rb"
+    # One check per threshold family; each reads better next to the others.
+    - "lib/simplecov/coverage_violations.rb"
+    # One usage document; its length is the command surface, not logic.
+    - "lib/simplecov/cli/usage.rb"
+    # One home for the per-construct, per-Ruby-version Coverage location
+    # conventions; splitting it would scatter closely-related resolvers.
+    - "lib/simplecov/static_coverage_extractor/location_conventions.rb"
+    # One check per section the viewer reads; the length tracks the
+    # document's surface, not an accumulation of concerns.
+    - "lib/simplecov/formatter/html_formatter/viewer_data_validator.rb"
+    # One cohesive sandbox harness; splitting it would scatter
+    # closely-related helpers.
+    - "spec/support/sandbox_project.rb"
+
+Metrics/ClassLength:
+  Exclude:
+    # The same two one-concern homes the ModuleLength exclusions cover;
+    # this cop counts their `class << self` bodies.
+    - "lib/simplecov/production.rb"
+    - "lib/simplecov/coverage_violations.rb"
+
+Metrics/MethodLength:
+  Exclude:
+    - "spec/support/dogfood_report.rb"
+
+Metrics/AbcSize:
+  Exclude:
+    - "spec/support/dogfood_report.rb"
 
 Metrics/BlockLength:
   Description: Checks if the length of a block exceeds some maximum value.
@@ -69,31 +98,46 @@ Metrics/ParameterLists:
 Naming/FileName:
   Description: makes sure that Ruby source files have snake_case names.
   Exclude:
-    - "spec/fixtures/utf-8.rb"
     - "lib/simplecov-html.rb"
 
+Naming/PredicateMethod:
+  # Commands that report whether they acted. Their names are verbs
+  # because the action is the point and the boolean is the receipt, so
+  # neither a `?` (they are not questions) nor a bare command (callers
+  # do read the answer) would say it better.
+  AllowedMethods:
+    - stop
+    - store
+    - store_result
+    - remove_filter
+    - warn_decline
+
 inherit_mode:
   merge:
     - Exclude
 
-# Spec fixtures are byte-stable test inputs (line numbers and `puts`
-# statements matter for coverage assertions), and spec/support/ holds
-# helper modules — neither directory is a real spec suite, so the
-# RSpec department shouldn't touch them. (The fixture rspec runners
-# under spec/fixtures/frameworks/ are intentionally minimal:
-# `expect(1).to eq(2)` is the point.)
+# spec/support/ holds helper modules, not a spec suite, so the RSpec
+# department shouldn't touch it. (Fixtures are excluded wholesale under
+# AllCops.)
 RSpec:
   Exclude:
-    - "spec/fixtures/**/*"
     - "spec/support/**/*"
-RSpec/ExpectActual:
-  Exclude:
-    - "spec/fixtures/**/*"
 RSpec/DescribeClass:
   Exclude:
-    - "spec/fixtures/**/*"
     # End-to-end sandbox specs describe user-visible behaviors, not classes.
     - "spec/sandbox/**/*"
+    # These specs describe cross-cutting behaviors and contracts —
+    # exit codes, output streams, file formats, build artifacts — that
+    # no single class owns.
+    - "spec/assets_spec.rb"
+    - "spec/config_loader_spec.rb"
+    - "spec/coverage_for_eval_spec.rb"
+    - "spec/deleted_source_spec.rb"
+    - "spec/formatter/coverage_schema_spec.rb"
+    - "spec/gemspec_spec.rb"
+    - "spec/production_integration_spec.rb"
+    - "spec/return_codes_spec.rb"
+    - "spec/stderr_output_spec.rb"
 
 RSpec/ExampleLength:
   Max: 20 # TODO: Lower to 5
@@ -124,13 +168,18 @@ Style/CollectionMethods:
     find: "detect"
     find_all: "select"
 
+Style/ClassVars:
+  Exclude:
+    # The minitest plugin's arming flag is a class variable on
+    # Minitest itself, so the fakes standing in for Minitest here have
+    # to carry one too.
+    - "spec/simplecov_spec.rb"
+
 Style/FrozenStringLiteralComment:
   Description:
     Add the frozen_string_literal comment to the top of files to help transition
     from Ruby 2.3.0 to Ruby 3.0.
   EnforcedStyle: always
-  Exclude:
-    - "spec/fixtures/**/*"
 
 Style/EnvHome:
   # `Dir.home` raises ArgumentError on JRuby when HOME is unset, defeating

lib/simplecov/cli/usage.rb

@@ -5,8 +5,6 @@ module CLI
     # The `simplecov help` text. A method so its default paths resolve at
     # call time against the active `.simplecov`.
     #
-    # rubocop:disable Metrics/ModuleLength -- the module is one usage
-    # document; its length is the command surface, not logic.
     module Usage
       extend self
 
@@ -153,6 +151,5 @@ def text(cli)
         USAGE
       end
     end
-    # rubocop:enable Metrics/ModuleLength
   end
 end

lib/simplecov/configuration/filters.rb

@@ -111,7 +111,7 @@ def add_filter(filter_argument = nil, &block)
     # Returns true when at least one filter was removed, false otherwise.
     # `reject!` answers nil when it rejected nothing, which is the whole
     # of "was anything removed".
-    def remove_filter(filter_argument) # rubocop:disable Naming/PredicateMethod
+    def remove_filter(filter_argument)
       rejected = filters.reject! do |filter|
         filter.respond_to?(:filter_argument) && filter.filter_argument.eql?(filter_argument)
       end

lib/simplecov/coverage_violations.rb

@@ -7,9 +7,6 @@ module SimpleCov
   # Each method returns an array of violation hashes. All percents are
   # rounded via `SimpleCov.round_coverage` so downstream consumers don't
   # need to round again.
-  # rubocop:disable Metrics/ModuleLength, Metrics/ClassLength -- one check
-  # per threshold family, and each reads better next to the others than
-  # split across files by size alone.
   module CoverageViolations
     class << self
       # @return [Array<Hash>] {:criterion, :expected, :actual}
@@ -320,5 +317,4 @@ def round(percent)
       end
     end
   end
-  # rubocop:enable Metrics/ModuleLength, Metrics/ClassLength
 end

lib/simplecov/formatter/html_formatter/viewer_data_validator.rb

@@ -9,7 +9,6 @@ class HTMLFormatter
       # dereferences without defensive fallbacks. One check per section
       # the viewer reads; the module's length tracks the document's
       # surface, not an accumulation of concerns.
-      # rubocop:disable-next Metrics/ModuleLength
       module ViewerDataValidator
         META_STRINGS = %w[simplecov_version command_name project_name timestamp].freeze
         COVERAGE_FLAGS = {

lib/simplecov/production.rb

@@ -25,7 +25,6 @@ module SimpleCov
   # See the file-top comment. One cohesive runtime state machine; kept
   # in one class for the same reason a state machine is not split
   # across files by size alone.
-  # rubocop:disable-next Metrics/ModuleLength, Metrics/ClassLength
   module Production
     class << self
       # Begin measuring. Returns true when measurement started, false —
@@ -86,7 +85,7 @@ def flush
       # Stop measuring: wind down the flush thread, deliver the final
       # delta, and halt the runtime's instrumentation. Returns false
       # when nothing was running.
-      def stop # rubocop:disable Naming/PredicateMethod -- a command that reports whether it acted
+      def stop
         return false unless running?
 
         @running = false
@@ -276,7 +275,7 @@ def relativize(path)
         path[@root_prefix.length..]
       end
 
-      def warn_decline(reason) # rubocop:disable Naming/PredicateMethod -- the callers' falsy return value
+      def warn_decline(reason)
         warn "[SimpleCov::Production] not starting: #{reason}"
         false
       end

lib/simplecov/production/file_sink.rb

@@ -49,7 +49,7 @@ def initialize(path:)
         @path = File.expand_path(path)
       end
 
-      def store(coverage) # rubocop:disable Naming/PredicateMethod -- the sink contract returns acceptance
+      def store(coverage)
         FileUtils.mkdir_p(File.dirname(path))
         locked do |file|
           existing = self.class.parse(file.read, path)

lib/simplecov/result_merger.rb

@@ -173,7 +173,7 @@ def read_resultset
       end
 
       # Saves the given SimpleCov::Result in the resultset cache
-      def store_result(result) # rubocop:disable Naming/PredicateMethod
+      def store_result(result)
         synchronize_resultset do
           # Ensure we have the latest, in case it was already cached
           new_resultset = read_resultset

lib/simplecov/static_coverage_extractor/location_conventions.rb

@@ -10,9 +10,6 @@ module StaticCoverageExtractor
     # changed several of these conventions, so every resolver here emits
     # whichever shape this Ruby's Coverage uses. See issues #1226 / #1233.
     #
-    # rubocop:disable Metrics/ModuleLength -- one cohesive home for the
-    # per-construct, per-Ruby-version Coverage location conventions;
-    # splitting it would scatter closely-related resolvers.
     module LocationConventions
       LEGACY_COVERAGE_LOCATIONS = Gem::Version.new(RUBY_VERSION) < Gem::Version.new("3.4")
 
@@ -244,6 +241,5 @@ def value_position?(node)
       end
       # simplecov:enable
     end
-    # rubocop:enable Metrics/ModuleLength
   end
 end

spec/assets_spec.rb

@@ -4,7 +4,7 @@
 require "open3"
 require "tmpdir"
 
-RSpec.describe "frontend asset compilation" do # rubocop:disable RSpec/DescribeClass
+RSpec.describe "frontend asset compilation" do
   it "fails when the CSS minifier exits unsuccessfully" do
     skip "the fake esbuild is a POSIX shell script" if Gem.win_platform?