Prevent collisions on let(:name) and let(:method_name)

lib/rspec/rails/fixture_support.rb

@@ -9,11 +9,11 @@ module FixtureSupport
         include RSpec::Rails::MinitestAssertionAdapter
         include ActiveRecord::TestFixtures
 
-        if ::Rails.version.to_f >= 6.1
-          # @private return the example name for TestFixtures
-          def name
-            @example
-          end
+        # @private prevent ActiveSupport::TestFixtures to start a DB transaction.
+        # Monkey patched to avoid collisions with 'let(:name)' in Rails 6.1 and after
+        # and let(:method_name) before Rails 6.1.
+        def run_in_transaction?
+          use_transactional_tests && !self.class.uses_transaction?(self)
         end
 
         included do

snippets/avoid_fixture_name_collision.rb

@@ -0,0 +1,57 @@
+if __FILE__ =~ /^snippets/
+  fail "Snippets are supposed to be run from their own directory to avoid side " \
+       "effects as e.g. the root `Gemfile`, or `spec/spec_helpers.rb` to be " \
+       "loaded by the root `.rspec`."
+end
+
+# We opt-out from using RubyGems, but `bundler/inline` requires it
+require 'rubygems'
+
+require "bundler/inline"
+
+# We pass `false` to `gemfile` to skip the installation of gems,
+# because it may install versions that would conflict with versions
+# from the main `Gemfile.lock`.
+gemfile(false) do
+  source "https://rubygems.org"
+
+  git_source(:github) { |repo| "https://github.com/#{repo}.git" }
+
+  # Those Gemfiles carefully pick the right versions depending on
+  # settings in the ENV, `.rails-version` and `maintenance-branch`.
+  Dir.chdir('..') do
+    eval_gemfile 'Gemfile-sqlite-dependencies'
+    # This Gemfile expects `maintenance-branch` file to be present
+    # in the current directory.
+    eval_gemfile 'Gemfile-rspec-dependencies'
+    # This Gemfile expects `.rails-version` file
+    eval_gemfile 'Gemfile-rails-dependencies'
+  end
+
+  gem "rspec-rails", path: "../"
+end
+
+# Run specs at exit
+require "rspec/autorun"
+
+require "rails"
+require "active_record/railtie"
+require "rspec/rails"
+
+# This connection will do for database-independent bug reports
+ActiveRecord::Base.establish_connection(adapter: "sqlite3", database: ":memory:")
+
+RSpec.configure do |config|
+  config.use_transactional_fixtures = true
+end
+
+RSpec.describe 'Foo' do
+  subject { true }
+
+  # Rails 6.1 and after
+  let(:name) { raise "Should never raise" }
+  # Before Rails 6.1
+  let(:method_name) { raise "Should never raise" }
+
+  it { is_expected.to be_truthy }
+end