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parallel_test_sharding

⚡ Parallel Test Execution and Sharding​

Leverage test-level parallelism and custom sharding logic to run large suites across multiple cores or CI nodes. Use parallelize_me! in Rails, or manually fork processes for pure Ruby.

# test/test_helper.rb
require 'parallel_tests'

class ActiveSupport::TestCase
  # automatically splits tests into N shards
  parallelize(workers: ENV.fetch('TEST_WORKERS', 4).to_i)
end

In CI, set TEST_WORKERS per node and specify TEST_ENV_NUMBER to pick a shard:

# On Node 1
TEST_WORKERS=4 TEST_ENV_NUMBER=1 bundle exec rake test
# On Node 2
TEST_WORKERS=4 TEST_ENV_NUMBER=2 bundle exec rake test