Add AllowNil config option to Lint/SuppressedException (rubocop#9546)

changelog/new_added_allow_rescue_nil_config_to_suppressed_exception.md

@@ -0,0 +1 @@
+* Add `AllowNil` option for `Lint/SuppressedException` to allow/disallow `rescue nil`. ([@corroded][])

config/default.yml

@@ -2055,8 +2055,9 @@ Lint/SuppressedException:
   StyleGuide: '#dont-hide-exceptions'
   Enabled: true
   AllowComments: true
+  AllowNil: true
   VersionAdded: '0.9'
-  VersionChanged: '0.81'
+  VersionChanged: <<next>>
 
 Lint/SymbolConversion:
   Description: 'Checks for unnecessary symbol conversions.'

lib/rubocop/cop/lint/suppressed_exception.rb

@@ -64,12 +64,51 @@ module Lint
       #   rescue
       #     # do nothing
       #   end
+      #
+      # @example AllowNil: true (default)
+      #
+      #   # good
+      #   def some_method
+      #     do_something
+      #   rescue
+      #     nil
+      #   end
+      #
+      #   # good
+      #   begin
+      #     do_something
+      #   rescue
+      #     # do nothing
+      #   end
+      #
+      #   # good
+      #   do_something rescue nil
+      #
+      # @example AllowNil: false
+      #
+      #   # bad
+      #   def some_method
+      #     do_something
+      #   rescue
+      #     nil
+      #   end
+      #
+      #   # bad
+      #   begin
+      #     do_something
+      #   rescue
+      #     nil
+      #   end
+      #
+      #   # bad
+      #   do_something rescue nil
       class SuppressedException < Base
         MSG = 'Do not suppress exceptions.'
 
         def on_resbody(node)
-          return if node.body
+          return if node.body && !nil_body?(node)
           return if cop_config['AllowComments'] && comment_between_rescue_and_end?(node)
+          return if cop_config['AllowNil'] && nil_body?(node)
 
           add_offense(node)
         end
@@ -83,6 +122,10 @@ def comment_between_rescue_and_end?(node)
           end_line = ancestor.loc.end.line
           processed_source[node.first_line...end_line].any? { |line| comment_line?(line) }
         end
+
+        def nil_body?(node)
+          node.body&.nil_type?
+        end
       end
     end
   end

spec/rubocop/cop/lint/suppressed_exception_spec.rb

@@ -47,6 +47,48 @@ def foo
           end
         RUBY
       end
+
+      context 'with AllowNil set to true' do
+        let(:cop_config) { { 'AllowComments' => false, 'AllowNil' => true } }
+
+        it 'does not register an offense for rescue block with nil' do
+          expect_no_offenses(<<~RUBY)
+            begin
+              do_something
+            rescue
+              nil
+            end
+          RUBY
+        end
+
+        it 'does not register an offense for inline nil rescue' do
+          expect_no_offenses(<<~RUBY)
+            something rescue nil
+          RUBY
+        end
+      end
+
+      context 'with AllowNil set to false' do
+        let(:cop_config) { { 'AllowComments' => false, 'AllowNil' => false } }
+
+        it 'registers an offense for rescue block with nil' do
+          expect_offense(<<~RUBY)
+            begin
+              do_something
+            rescue
+            ^^^^^^ Do not suppress exceptions.
+              nil
+            end
+          RUBY
+        end
+
+        it 'registers an offense for inline nil rescue' do
+          expect_offense(<<~RUBY)
+            something rescue nil
+                      ^^^^^^^^^^ Do not suppress exceptions.
+          RUBY
+        end
+      end
     end
 
     context 'when empty rescue for defs' do