Introduce and fix new cops

.rubocop.yml

@@ -55,22 +55,52 @@ Lint/AmbiguousRegexpLiteral:
     - "spec/**/*_steps.rb"
     - "tmp/**/*_steps.rb"
 
+Lint/BinaryOperatorWithIdenticalOperands:
+  Enabled: true
+
 Lint/DeprecatedOpenSSLConstant:
   Description: Don't use algorithm constants for `OpenSSL::Cipher` and `OpenSSL::Digest`.
   Enabled: true
 
+Lint/DuplicateElsifCondition:
+  Enabled: true
+
+Lint/DuplicateRescueException:
+  Enabled: true
+
+Lint/EmptyConditionalBody:
+  Enabled: true
+
+Lint/FloatComparison:
+  Enabled: true
+
+Lint/MissingSuper:
+  Enabled: true
+
 Lint/MixedRegexpCaptureTypes:
   Description: Do not mix named captures and numbered captures in a Regexp literal.
   Enabled: true
 
+Lint/OutOfRangeRegexpRef:
+  Enabled: true
+
 Lint/RaiseException:
   Description: Checks for `raise` or `fail` statements which are raising `Exception` class.
   Enabled: true
 
+Lint/SelfAssignment:
+  Enabled: true
+
 Lint/StructNewOverride:
   Description: Disallow overriding the `Struct` built-in methods via `Struct.new`.
   Enabled: true
 
+Lint/TopLevelReturnWithArgument:
+  Enabled: true
+
+Lint/UnreachableLoop:
+  Enabled: true
+
 Metrics/AbcSize:
   Description: Checks that the ABC size of methods is not higher than the configured maximum.
   Max: 25 # TODO: Lower to 15
@@ -109,6 +139,18 @@ Naming/FileName:
   Exclude:
     - "spec/fixtures/utf-8.rb"
 
+Style/AccessorGrouping:
+    Enabled: true
+
+Style/ArrayCoercion:
+    Enabled: true
+
+Style/BisectedAttrAccessor:
+    Enabled: true
+
+Style/CaseLikeIf:
+    Enabled: true
+
 Style/CollectionMethods:
   Description: Enforces the use of consistent method names from the Enumerable module.
   PreferredMethods:
@@ -126,6 +168,10 @@ Style/DoubleNegation:
   StyleGuide: https://github.com/rubocop-hq/ruby-style-guide#no-bang-bang
   Enabled: false
 
+Style/ExplicitBlockArgument:
+    # capturing as a proc has a performance hit, so is a case by case choice
+    Enabled: false
+
 Style/ExponentialNotation:
   Description: When using exponential notation, favor a mantissa between 1 (inclusive) and 10 (exclusive).
   Enabled: true
@@ -139,14 +185,23 @@ Style/FrozenStringLiteralComment:
   Exclude:
     - "spec/fixtures/**/*"
 
+Style/GlobalStdStream:
+    Enabled: true
+
 Style/GuardClause:
   Description: Use a guard clause instead of wrapping the code inside a conditional expression.
   Enabled: false
 
+Style/HashAsLastArrayItem:
+    Enabled: true
+
 Style/HashEachMethods:
   Description: Use Hash#each_key and Hash#each_value.
   Enabled: true
 
+Style/HashLikeCase:
+    Enabled: true
+
 Style/HashTransformKeys:
   Description: Prefer `transform_keys` over `each_with_object` and `map`.
   Enabled: true
@@ -159,6 +214,18 @@ Style/HashSyntax:
   Description: Checks hash literal syntax.
   EnforcedStyle: ruby19
 
+Style/OptionalBooleanParameter:
+    Enabled: true
+
+Style/RedundantAssignment:
+    Enabled: true
+
+Style/RedundantFetchBlock:
+    Enabled: true
+
+Style/RedundantFileExtensionInRequire:
+    Enabled: true
+
 Style/RedundantRegexpCharacterClass:
   Description: Checks for unnecessary single-element Regexp character classes.
   Enabled: true
@@ -172,6 +239,9 @@ Style/RegexpLiteral:
   StyleGuide: https://github.com/rubocop-hq/ruby-style-guide#percent-r
   Enabled: false
 
+Style/SingleArgumentDig:
+    Enabled: true
+
 Style/SlicingWithRange:
   Description: Checks array slicing is done with endless ranges when suitable.
   Enabled: true
@@ -183,6 +253,9 @@ Style/SpecialGlobalVars:
     - "spec/return_codes_spec.rb"
     - "lib/simplecov/defaults.rb"
 
+Style/StringConcatenation:
+    Enabled: true
+
 Style/StringLiterals:
   Description: Allow double-quoted strings without interpolation.
   EnforcedStyle: double_quotes

lib/simplecov.rb

@@ -23,8 +23,7 @@
 #
 module SimpleCov
   class << self
-    attr_accessor :running
-    attr_accessor :pid
+    attr_accessor :running, :pid
     attr_reader :exit_exception
 
     # Basically, should we take care of at_exit behavior or something else?

lib/simplecov/filter.rb

@@ -35,13 +35,14 @@ def self.build_filter(filter_argument)
     end
 
     def self.class_for_argument(filter_argument)
-      if filter_argument.is_a?(String)
+      case filter_argument
+      when String
         SimpleCov::StringFilter
-      elsif filter_argument.is_a?(Regexp)
+      when Regexp
         SimpleCov::RegexFilter
-      elsif filter_argument.is_a?(Array)
+      when Array
         SimpleCov::ArrayFilter
-      elsif filter_argument.is_a?(Proc)
+      when Proc
         SimpleCov::BlockFilter
       else
         raise ArgumentError, "You have provided an unrecognized filter type"

lib/simplecov/formatter/multi_formatter.rb

@@ -25,7 +25,7 @@ def self.new(formatters = nil)
 
       def self.[](*args)
         warn "#{Kernel.caller.first}: [DEPRECATION] ::[] is deprecated. Use ::new instead."
-        new(Array([*args]))
+        new(Array(args))
       end
     end
   end

spec/filters_spec.rb

@@ -192,8 +192,8 @@ def a_file(path)
       end
 
       it "filters even if the sibling directory has SimpleCov.root as a prefix" do
-        sibling_dir = SimpleCov.root + "_cache"
-        expect(SimpleCov.filtered([a_file(sibling_dir + "/foo.rb")]).count).to eq(0)
+        sibling_dir = "#{SimpleCov.root}_cache"
+        expect(SimpleCov.filtered([a_file("#{sibling_dir}/foo.rb")]).count).to eq(0)
       end
     end
   end

spec/result_merger_spec.rb

@@ -135,22 +135,26 @@
     it "blocks other processes" do
       file = Tempfile.new("foo")
 
-      other_process = open("|ruby -e " + Shellwords.escape(<<-CODE) + " 2>/dev/null") # rubocop:disable Security/Open
-        require "simplecov"
-        SimpleCov.coverage_dir(#{SimpleCov.coverage_dir.inspect})
+      test_script = <<-CODE
+      require "simplecov"
+      SimpleCov.coverage_dir(#{SimpleCov.coverage_dir.inspect})
 
-        # ensure the parent process has enough time to get a
-        # lock before we do
-        sleep 0.5
+      # ensure the parent process has enough time to get a
+      # lock before we do
+      sleep 0.5
 
-        $stdout.sync = true
-        puts "running" # see `sleep`s in parent process
+      $stdout.sync = true
+      puts "running" # see `sleep`s in parent process
 
-        SimpleCov::ResultMerger.synchronize_resultset do
-          File.open(#{file.path.inspect}, "a") { |f| f.write("process 2\n") }
-        end
+      SimpleCov::ResultMerger.synchronize_resultset do
+        File.open(#{file.path.inspect}, "a") { |f| f.write("process 2\n") }
+      end
       CODE
 
+      # rubocop:disable Security/Open
+      other_process = open("|ruby -e #{Shellwords.escape(test_script)} 2>/dev/null")
+      # rubocop:enable Security/Open
+
       SimpleCov::ResultMerger.synchronize_resultset do
         # wait until the child process is going, and then wait some more
         # so we can be sure it blocks on the lock we already have.

spec/return_codes_spec.rb

@@ -39,7 +39,7 @@
       end
 
       context "when print_error_status is disabled" do
-        let(:command) { "PRINT_ERROR_STATUS=false " + super() }
+        let(:command) { "PRINT_ERROR_STATUS=false #{super()}" }
 
         it "has a non-zero exit status" do
           expect(@status.exitstatus).not_to be_zero