Fix Lint/UnusedBlockArgument cop.

.rubocop_todo.yml

@@ -47,13 +47,6 @@ Lint/SuppressedException:
     - 'test/ioextras/abstract_input_stream_test.rb'
     - 'test/local_entry_test.rb'
 
-# Offense count: 1
-# Cop supports --auto-correct.
-# Configuration parameters: IgnoreEmptyBlocks, AllowUnusedKeywordArguments.
-Lint/UnusedBlockArgument:
-  Exclude:
-    - 'test/file_test.rb'
-
 # Offense count: 1
 # Configuration parameters: ContextCreatingMethods, MethodCreatingMethods.
 Lint/UselessAccessModifier:

test/file_test.rb

@@ -131,7 +131,7 @@ class ZipFileTest < MiniTest::Test
       # Note: this may change the file if it is opened with r+b instead of rb.
       # The 'extra fields' in this particular zip file get reordered.
       File.open(test_zip, 'rb') do |file|
-        Zip::File.open_buffer(file) do |zf|
+        Zip::File.open_buffer(file) do
           nil # do nothing
         end
       end