ifmeorg/ifme

Checks for redundant safe navigation calls. instance_of?, kind_of?, is_a?, eql?, respond_to?, and equal? methods are checked by default. These are customizable with AllowedMethods option.

The AllowedMethods option specifies nil-safe methods, in other words, it is a method that is allowed to skip safe navigation. Note that the AllowedMethod option is not an option that specifies methods for which to suppress (allow) this cop's check.

In the example below, the safe navigation operator (&.) is unnecessary because NilClass has methods like respond_to? and is_a?.

Safety:

This cop is unsafe, because autocorrection can change the return type of the expression. An offending expression that previously could return nil will be autocorrected to never return nil.

Example:

# bad
do_something if attrs&.respond_to?(:[])

# good
do_something if attrs.respond_to?(:[])

# bad
while node&.is_a?(BeginNode)
  node = node.parent
end

# good
while node.is_a?(BeginNode)
  node = node.parent
end

# good - without `&.` this will always return `true`
foo&.respond_to?(:to_a)

Example: AllowedMethods: [nilsafemethod]

# bad
do_something if attrs&.nil_safe_method(:[])

# good
do_something if attrs.nil_safe_method(:[])
do_something if attrs&.not_nil_safe_method(:[])

Identifies places where if-elsif constructions can be replaced with case-when.

Safety:

This cop is unsafe. case statements use === for equality, so if the original conditional used a different equality operator, the behavior may be different.

Example: MinBranchesCount: 3 (default)

# bad
if status == :active
  perform_action
elsif status == :inactive || status == :hibernating
  check_timeout
elsif status == :invalid
  report_invalid
else
  final_action
end

# good
case status
when :active
  perform_action
when :inactive, :hibernating
  check_timeout
when :invalid
  report_invalid
else
  final_action
end

Example: MinBranchesCount: 4

# good
if status == :active
  perform_action
elsif status == :inactive || status == :hibernating
  check_timeout
elsif status == :invalid
  report_invalid
else
  final_action
end