Lint-RedundantSafeNavigation.md

Pattern: Redundant safe navigation

Issue: -

Description

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.

This rule is marked as unsafe, because auto-correction can change the return type of the expression. An offending expression that previously could return nil will be auto-corrected to never return nil.

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

Examples

# 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)

Further Reading

• RuboCop - Lint/RedundantSafeNavigation