Fix flaky testing for Minitst/MultipleAssertions

The shared `@cop` instance variable of `AssertOffense` module
causes flaky tests due to state changes.

The `AssertOffense` testing module needs to be updated to allow for tests
that are independent in configuration between tests.
It is necessary to prevent race conditions caused by shared configurations.

This is a workaround to skip tests until the issue is resolved in `AssertOffense` module.

.github/workflows/test.yml

@@ -84,5 +84,3 @@ jobs:
           bundler-cache: true
       - name: test
         run: bundle exec rake test
-        env:
-          ERROR_ON_TEST_FAILURE: "false"

Rakefile

@@ -29,9 +29,7 @@ if RUBY_ENGINE == 'jruby' || RuboCop::Platform.windows?
 else
   desc 'Run tests'
   task :test do
-    error_on_failure = ENV.fetch('ERROR_ON_TEST_FAILURE', 'true') != 'false'
-
-    system("bundle exec minitest-queue #{Dir.glob('test/**/*_test.rb').shelljoin}", exception: error_on_failure)
+    sh("bundle exec minitest-queue #{Dir.glob('test/**/*_test.rb').shelljoin}")
   end
 end
 

test/rubocop/cop/minitest/multiple_assertions_test.rb

@@ -186,9 +186,9 @@ class FooTest < ActiveSupport::TestCase
           err = assert_raises React::ServerRendering::PrerenderError do
             @renderer.render("NonExistentComponent", {}, nil)
           end
-    
+
           assert_match(/NonExistentComponent/, err.to_s, "it names the component")
-    
+
           assert_match(/\n/, err.to_s, "it includes the multi-line backtrace")
         end
       end
@@ -205,9 +205,9 @@ class FooTest < ActiveSupport::TestCase
             assert_equal 1, 1
             assert_equal 1, 1
           end
-    
+
           assert_match(/NonExistentComponent/, err.to_s, "it names the component")
-    
+
           assert_match(/\n/, err.to_s, "it includes the multi-line backtrace")
         end
       end
@@ -231,9 +231,9 @@ class FooTest < ActiveSupport::TestCase
               assert_equal 1, 1
             end
           end
-    
+
           assert_match(/NonExistentComponent/, err.to_s, "it names the component")
-    
+
           assert_match(/\n/, err.to_s, "it includes the multi-line backtrace")
         end
       end
@@ -292,6 +292,8 @@ def test_asserts_once
   end
 
   def test_generates_a_todo_based_on_the_worst_violation
+    skip 'FIXME: The shared `@cop` instance variable causes flaky tests due to state changes.'
+
     inspect_source(<<-RUBY, @cop, 'test/foo_test.rb')
       class FooTest < Minitest::Test
         def test_asserts_once
@@ -533,6 +535,8 @@ class FooTest < ActiveSupport::TestCase
   end
 
   def test_registers_offense_when_complex_structure_with_multiple_assertions
+    skip 'FIXME: The shared `@cop` instance variable causes flaky tests due to state changes.'
+
     configure_max_assertions(2)
 
     assert_offense(<<~RUBY)
@@ -572,6 +576,8 @@ class FooTest < ActiveSupport::TestCase
   end
 
   def test_registers_offense_when_complex_structure_with_assignments_and_multiple_assertions
+    skip 'FIXME: The shared `@cop` instance variable causes flaky tests due to state changes.'
+
     configure_max_assertions(2)
 
     assert_offense(<<~RUBY)
@@ -611,6 +617,8 @@ class FooTest < ActiveSupport::TestCase
   end
 
   def test_registers_offense_when_complex_multiple_assignment_structure_and_multiple_assertions
+    skip 'FIXME: The shared `@cop` instance variable causes flaky tests due to state changes.'
+
     configure_max_assertions(2)
 
     assert_offense(<<~RUBY)