Counting the number of queries performed

Question

I\'d like to test that a certain piece of code performs as few SQL queries as possible.

ActiveRecord::TestCase seems to have its own assert_querie

Answer 1

• helpful error message
• removes subscribers after execution

(based on Jaime Cham's answer)

class ActiveSupport::TestCase
  def sql_queries(&block)
    queries = []
    counter = ->(*, payload) {
      queries << payload.fetch(:sql) unless ["CACHE", "SCHEMA"].include?(payload.fetch(:name))
    }

    ActiveSupport::Notifications.subscribed(counter, "sql.active_record", &block)

    queries
  end

  def assert_sql_queries(expected, &block)
    queries = sql_queries(&block)
    queries.count.must_equal(
      expected,
      "Expected #{expected} queries, but found #{queries.count}:\n#{queries.join("\n")}"
    )
  end
end