Update rubocop

[difernandez]

Changes

• Updates rubocop and rubocop-rspec to latest versions (rubocop-rspec < 2.0 is incompatible with rubocop 1.x)
• Use same version for potassium and generated projects

Rules

The following rules are new and enabled by default with this change:

New rules

Style/SlicingWithRange:
  Description: 'Checks array slicing is done with endless ranges when suitable.'
Layout/EmptyLinesAroundAttributeAccessor:
  Description: "Keep blank lines around attribute accessors."
Lint/DeprecatedOpenSSLConstant:
  Description: "Don't use algorithm constants for `OpenSSL::Cipher` and `OpenSSL::Digest`."
Style/RedundantRegexpCharacterClass:
  Description: 'Checks for unnecessary single-element Regexp character classes.'
Style/RedundantRegexpEscape:
  Description: 'Checks for redundant escapes in Regexps.'
Lint/MixedRegexpCaptureTypes:
  Description: 'Do not mix named captures and numbered captures in a Regexp literal.'
Style/RedundantFetchBlock:
  Description: >-
                  Use `fetch(key, value)` instead of `fetch(key) { value }`
                  when value has Numeric, Rational, Complex, Symbol or String type, `false`, `true`, `nil` or is a constant.
Style/AccessorGrouping:
  Description: 'Checks for grouping of accessors in `class` and `module` bodies.'
Style/BisectedAttrAccessor:
  Description: >-
                Checks for places where `attr_reader` and `attr_writer`
                for the same method can be combined into single `attr_accessor`.
Style/RedundantAssignment:
  Description: 'Checks for redundant assignment before returning.'
Lint/DuplicateElsifCondition:
  Description: 'Do not repeat conditions used in if `elsif`.'
Style/CaseLikeIf:
  Description: 'This cop identifies places where `if-elsif` constructions can be replaced with `case-when`.'
Style/HashAsLastArrayItem:
  Description: >-
                Checks for presence or absence of braces around hash literal as a last
                array item depending on configuration.
Style/HashLikeCase:
  Description: >-
                  Checks for places where `case-when` represents a simple 1:1
                  mapping and can be replaced with a hash lookup.
Style/RedundantFileExtensionInRequire:
  Description: >-
                  Checks for the presence of superfluous `.rb` extension in
                  the filename provided to `require` and `require_relative`.
Lint/DuplicateRescueException:
  Description: 'Checks that there are no repeated exceptions used in `rescue` expressions.'
Lint/EmptyConditionalBody:
  Description: 'This cop checks for the presence of `if`, `elsif` and `unless` branches without a body.'
Lint/FloatComparison:
  Description: 'Checks for the presence of precise comparison of floating point numbers.'
Lint/MissingSuper:
  Description: >-
                  This cop checks for the presence of constructors and lifecycle callbacks
                  without calls to `super`'.
Lint/OutOfRangeRegexpRef:
  Description: 'Checks for out of range reference for Regexp because it always returns nil.'
Lint/SelfAssignment:
  Description: 'Checks for self-assignments.'
Lint/TopLevelReturnWithArgument:
  Description: 'This cop detects top level return statements with argument.'
Lint/UnreachableLoop:
  Description: 'This cop checks for loops that will have at most one iteration.'
Style/ExplicitBlockArgument:
  Description: >-
                  Consider using explicit block argument to avoid writing block literal
                  that just passes its arguments to another block.
Style/GlobalStdStream:
  Description: 'Enforces the use of `$stdout/$stderr/$stdin` instead of `STDOUT/STDERR/STDIN`.'
Style/OptionalBooleanParameter:
  Description: 'Use keyword arguments when defining method with boolean argument.'
Style/SingleArgumentDig:
  Description: 'Avoid using single argument dig method.'
Style/SoleNestedConditional:
  Description: >-
                  Finds sole nested conditional nodes
                  which can be merged into outer conditional node.
Style/StringConcatenation:
  Description: 'Checks for places where string concatenation can be replaced with string interpolation.'
Lint/DuplicateRequire:
  Description: 'Check for duplicate `require`s and `require_relative`s.'
Lint/EmptyFile:
  Description: 'Enforces that Ruby source files are not empty.'
Lint/TrailingCommaInAttributeDeclaration:
  Description: 'This cop checks for trailing commas in attribute declarations.'
Lint/UselessMethodDefinition:
  Description: 'Checks for useless method definitions.'
Style/CombinableLoops:
  Description: >-
                  Checks for places where multiple consecutive loops over the same data
                  can be combined into a single loop.
Style/KeywordParametersOrder:
  Description: 'Enforces that optional keyword parameters are placed at the end of the parameters list.'
Style/RedundantSelfAssignment:
  Description: 'Checks for places where redundant assignments are made for in place modification methods.'
Layout/BeginEndAlignment:
  Description: 'Align ends corresponding to begins correctly.'
Lint/ConstantDefinitionInBlock:
  Description: 'Do not define constants within a block.'
Lint/IdentityComparison:
  Description: 'Prefer `equal?` over `==` when comparing `object_id`.'
Lint/UselessTimes:
  Description: 'Checks for useless `Integer#times` calls.'
Lint/HashCompareByIdentity:
  Description: 'Prefer using `Hash#compare_by_identity` than using `object_id` for keys.'
Lint/RedundantSafeNavigation:
  Description: 'Checks for redundant safe navigation calls.'
Style/ClassEqualityComparison:
  Description: 'Enforces the use of `Object#instance_of?` instead of class comparison for equality.'

Looking at them, in general it seems to me that they wouldn't affect the way we work much. I think we could leave them enabled, but I would appreciate other opinions on this. There are a couple rules in particular I have doubts and I would like to know what you think:

• Style/CaseLikeIf: I'm not against it but maybe it's too opinionated? I don't see if-elsif as being too superior to case-when
• Style/RedundantFileExtensionInRequire: I like it for consistency, but don't know if it's too important
• Lint/MissingSuper: The example shows usage of super in a class without any parent, that confused me
• Style/OptionalBooleanParameter: didn't understand why it's better or why only for booleans
• Style/CombinableLoops: as the docs mention, it could lead to false positives
• Lint/HashCompareByIdentity: never used this, so I'm not sure I totally get it

Closes #336

[ldlsegovia]

• Style/CaseLikeIf like this, It is clearer to read.
• Style/RedundantFileExtensionInRequire not important as you say.
• Lint/MissingSuper Like the first case. I don't understand the last one.
• Style/OptionalBooleanParameter mmm I don't know why just with boolean values.
• Style/CombinableLoops. Like
• Lint/HashCompareByIdentity. I think it's about this. Like it