Some of my rubocop preferences

rubocop.yml

AllCops:
  Include:
  - "**/*.rake"
  - "**/Gemfile"
  - "**/Rakefile"
  Exclude:
  - "vendor/**/*"
  - "db/**/*"
  DisplayCopNames: true
  RunRailsCops: true
TrailingWhitespace:
  Enabled: false
Style/TrailingBlankLines:
  Enabled: false
Style/ExtraSpacing:
  Enabled: false
StringLiterals:
  EnforcedStyle: single_quotes
Metrics/LineLength:
  Max: 100
Style/DotPosition:
  EnforcedStyle: leading
Style/CommentAnnotation:
  Description: Checks formatting of special comments (TODO, FIXME, OPTIMIZE, HACK,
    REVIEW).
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#annotate-keywords
  Enabled: true
Rails/Delegate:
  Description: Prefer delegate method for delegations.
  Enabled: true
Style/FileName:
  Enabled: true
Style/GlobalVars:
  Enabled: true
Style/IfUnlessModifier:
  Description: Favor modifier if/unless usage when you have a single-line body.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#if-as-a-modifier
  Enabled: true
  MaxLineLength: 100
Style/Next:
  Description: Use `next` to skip iteration instead of a condition at the end.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-nested-conditionals
  Enabled: true
  EnforcedStyle: always
  SupportedStyles:
  - skip_modifier_ifs
  - always
Style/NumericLiterals:
  Description: Add underscores to large numeric literals to improve their readability.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#underscores-in-numerics
  Enabled: true
  MinDigits: 5
Style/PercentLiteralDelimiters:
  Description: Use `%`-literal delimiters consistently
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#percent-literal-braces
  Enabled: true
  PreferredDelimiters:
    "%": "()"
    "%i": "()"
    "%q": "()"
    "%Q": "()"
    "%r": "()"
    "%s": "()"
    "%w": "()"
    "%W": "()"
    "%x": "()"
Style/RegexpLiteral:
  Description: Use %r for regular expressions matching more than `MaxSlashes` '/'
    characters. Use %r only for regular expressions matching more than `MaxSlashes`
    '/' character.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#percent-r
  Enabled: true
Style/SignalException:
  Description: Checks for proper usage of fail and raise.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#fail-method
  Enabled: true
Style/SingleLineMethods:
  Description: Avoid single-line methods.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-single-line-methods
  Enabled: true
  AllowIfMethodIsEmpty: true
Style/TrivialAccessors:
  Enabled: true
  ExactNameMatch: false
  AllowPredicates: false
  AllowDSLWriters: false
  IgnoreClassMethods: false
  Whitelist:
    - to_ary
    - to_a
    - to_c
    - to_enum
    - to_h
    - to_hash
    - to_i
    - to_int
    - to_io
    - to_open
    - to_path
    - to_proc
    - to_r
    - to_regexp
    - to_str
    - to_s
    - to_sym
Style/WordArray:
  Description: Use %w or %W for arrays of words.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#percent-w
  Enabled: true
  MinSize: 0
  WordRegex: !ruby/regexp /\A[\p{Word}]+\z/
Metrics/ClassLength:
  Description: Avoid classes longer than 250 lines of code.
  Enabled: true
  CountComments: false
  Max: 250
Style/MethodCalledOnDoEndBlock:
  Description: Avoid chaining a method call on a do...end block.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#single-line-blocks
  Enabled: true
Style/SymbolArray:
  Description: Use %i or %I for arrays of symbols.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#percent-i
  Enabled: true
Style/AccessorMethodName:
  Description: Check the naming of accessor methods for get_/set_.
  Enabled: true
Style/CharacterLiteral:
  Description: Checks for uses of character literals.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-character-literals
  Enabled: true
Style/ClassVars:
  Description: Avoid the use of class variables.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-class-vars
  Enabled: true
Style/ColonMethodCall:
  Description: 'Do not use :: for method call.'
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#double-colons
  Enabled: true
Style/DeprecatedHashMethods:
  Description: Checks for use of deprecated Hash methods.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#hash-key
  Enabled: true
Style/DoubleNegation:
  Description: Checks for uses of double negation (!!).
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-bang-bang
  Enabled: true
Style/EachWithObject:
  Description: Prefer `each_with_object` over `inject` or `reduce`.
  Enabled: true
Style/EmptyLiteral:
  Description: Prefer literals to Array.new/Hash.new/String.new.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#literal-array-hash
  Enabled: true
Style/IfWithSemicolon:
  Description: Do not use if x; .... Use the ternary operator instead.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-semicolon-ifs
  Enabled: true
Style/Lambda:
  Description: Use the new lambda literal syntax for single-line blocks.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#lambda-multi-line
  Enabled: true
Style/LineEndConcatenation:
  Description: Use \ instead of + or << to concatenate two string literals at line
    end.
  Enabled: true
Style/ModuleFunction:
  Description: Checks for usage of `extend self` in modules.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#module-function
  Enabled: true
Style/NegatedIf:
  Description: Favor unless over if for negative conditions (or control flow or).
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#unless-for-negatives
  Enabled: true
Style/NegatedWhile:
  Description: Favor until over while for negative conditions.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#until-for-negatives
  Enabled: true
Style/NilComparison:
  Description: Prefer x.nil? to x == nil.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#predicate-methods
  Enabled: true
Style/SelfAssignment:
  Description: Checks for places where self-assignment shorthand should have been
    used.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#self-assignment
  Enabled: true
Style/StructInheritance:
  Description: Checks for inheritance from Struct.new.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#no-extend-struct-new
  Enabled: true
Style/VariableInterpolation:
  Description: Don't interpolate global, instance and class variables directly in
    strings.
  StyleGuide: https://github.com/bbatsov/ruby-style-guide#curlies-interpolate
  Enabled: true
Lint/UnderscorePrefixedVariableName:
  Description: Do not use prefix `_` for a variable that is used.
  Enabled: true
Style/MultilineOperationIndentation:
  Description: Checks indentation of binary operations that span more than one line.
  Enabled: true
  EnforcedStyle: aligned
  SupportedStyles:
  - aligned
  - indented